Color Cement Handicraft

	C O L O R CEMENT HANDICRAFT

Copyright, 1922
by The Davis Press, Inc.
Worcester, Mass.
Printed in the
United States of America
Dedicated to
ROBERT B. HARSHE
Director of the
Chicago Art Institute
for his early recognition
and encouragement
of Color Cement
Handicraft

TABLE OF CONTENTS

LIST OF ILLUSTRATIONS

FOREWORD

It is evident to the most casual observer that the use of cement and concrete has developed into a most important building material—undoubtedly the most important of the age. Industrial and vocational educators have recognized this importance and thousands of school children have received instruction in its use and application to objects of utility. Its use has been the subject of many books, and the reason for the issuing of this book is to present in printed form the use of color cement for the decoration or surface enrichment of cement and concrete objects. We heretofore have thought of cement in terms of rough surfaces and crude retaining walls, little thinking that beautiful patterns and textures are possible with proper combinations of color with cement, presenting possibilities for producing art tiles, pottery, and decorations of a high art quality.

After a study some years ago of the various forms of producing clay pottery and its possible relation to school arts and industrial education, the handicap of necessary firing to give permanency loomed large against its general adaptation by schools. This resulted in considerable research and experimenting by the authors with cement and the use of color in the endeavor to parallel in some measure each of the methods employed in the making of fired tiles and pottery. Particular attention was given to simplifying the process of securing permanent form to many of the plastic forms of schoolroom art, which have been presented in clay and other perishable mediums. With the projects presented in the following chapters permanent useful objects can be secured by students in their school art subjects. Attention was also given to the enriching or refining by decoration the many objects heretofore made in cement and concrete by vocational classes. The problems and methods explained in the following description solve this need.

Craftsmen or amateur home-workers who delight in creating and building objects of beauty around them can find in color cement a medium which will appeal to their needs, in that the necessary working equipment is simple and the work can be done within small space.

The following chapters by no means complete the story of color cement. They record the results of the work of the authors and it is hoped that it will stimulate interested readers to carry this delightful handicraft to even greater achievements.

The results achieved have been accomplished through several years’ patient experimenting by the authors, but the realization that many other teachers, craftsmen and students will be aided in continuing this delightful, durable handicraft, is in itself an enjoyable reward to the authors for their efforts.

Reta A. Lemos
Pedro J. Lemos

	CHAPTER 1 Materials and Equipment

IN THE MAKING OF COLOR CEMENT HANDICRAFT the chief material used is Portland cement. While this material has assumed a most important part in the building history of our present time, there are not many who know its history and source, and as every craftsman is a better craftsman if he knows something of the story of the material with which he works, here is the brief story of Portland cement.

PORTLAND CEMENT DERIVES ITS NAME because of resemblance in color to a stone quarried near Portland, England, and it was named by its inventor, Joseph Aspdin in 1824. It is a manufactured product produced by a scientific process. At the beginning of the Christian era the Romans used a natural cement very extensively, and many fragments of color frescoes and friezes remain from the work of the ancients, showing that they used color with their work.

THE PRINCIPAL INGREDIENTS OF PORTLAND CEMENT are lime, silica, iron, and alumina. These materials are mixed in definite proportions and then subjected to a degree of heat that almost causes them to melt, forming a clinker or slag. This clinker is ground until it is reduced to a powder, and this is the Portland cement. Portland cement is generally mixed with an aggregate to produce strength and this aggregate is usually stone, gravel or sand. The third material needed to complete the combination is water.

SUCCESS IN THE USE OF CEMENT depends largely upon cement that is fresh. Cement is very sensitive to moisture and if kept where fogs, dew or moisture of any nature is absorbed into it, the first set or “hydration” takes place and destroys its use for fine handicraft.

TO TEST FRESH CEMENT when the cement sack is open, thrust the hand into it and see that no hard lumps are in it. Fresh cement will feel slippery and soapy when rubbed between the finger tips. If it feels gritty and sandy it may do for the rough parts or body of vases and tiles, but only fresh cement should be used to mix with color and for surfacing purposes.

THE PROPER CARE OF CEMENT requires that it be kept in a covered receptacle and kept in a dry place, preferably up from the floor if the floor is near the ground. It should be kept in a dry, tight work-shop and the doors should be kept closed at night to avoid any moisture from the night air reaching it. Nothing can restore spoiled cement and it should not be used as the results will be discouraging.

GOOD GRADES OF AGGREGATES SHOULD BE USED in cement work. Clean sand should be used and a sand that is not too fine is preferable. Gravel and crushed rock used in large work such as garden seats, large bowls and outdoor problems should be of a good grade to form a good mixture.

THE WATER USED IN CEMENT WORK should be free from all impurities. Moderately warmed water will hasten the setting or hardening of cement while very cold water retards the hardening.

THERE ARE TWO COLORS OF CEMENT, gray and white. Portland cement is gray in color and a white cement is also made that is a refined form of cement. White cement is not as hard or durable as gray cement, but gives a smooth surface and sets as satisfactorily as the gray cement. It is more expensive than the gray cement and should not be used later than six months after the sack is opened.

WHEN CEMENT IS USED ALONE IT IS TERMED “NEAT.” When it is mixed with rock, gravel or sand it is termed “concrete.” Concrete produces strength and the neat cement produces a smooth texture and surface. When concrete is used the cement and water will rise to the top and if the surface is worked and pressed with a trowel the cement is “flowed” to the top, producing a smooth surface.

MOLDS ARE USED FOR FORMING CEMENT AND CONCRETE, and are made from wood, metal or plaster-of-Paris. The forms in all instances should be tied or braced together to prevent the moisture of the mixture from running out, as the water is essential to the successful hardening of the cement. In the making of cement pottery and tiles, plaster-of-Paris molds or forms are generally used and plaster-of-Paris therefore forms an important material in the making of color cement handicraft.

Plaster-of-Paris is made in different degrees of setting periods. These are quick-setting, medium-setting, and slow-setting. Casting plaster or sculptor’s plaster should be asked for and a medium-or slow-setting plaster is preferable for the beginner.

CEMENT, AGGREGATES, WATER AND PLASTER FORM THE MAIN PARTS of our working materials excepting the color, which is especially described in the chapter on Color.

THE EQUIPMENT for concrete pottery is simple, and much of it may be pressed into service from material to be found about the house or workshop. Inventive ingenuity on the part of the worker will find clever uses for many discarded kitchen utensils and unused tools.

Following is a list of convenient things needed to produce pottery. These may be added to or elaborated through personal requirements.

WORKING EQUIPMENT.

• galvanized iron pans about 2 x 3 feet
• 2 large spoons
• 4 or 5 pans
• 2 ladles
• 1 large file or rasp
• 2 table knives
• 3 pieces of ordinary glass about 12 x 18 inches
• 1 palette knife
• 1 lb. modeling wax
• 1 bristle brush ½ inch wide
• 2 small sable oil brushes, No. 1 or 2
• 1 small clay-modeling tool
• 2 pieces of thin wood for mixing paddles
• ½ doz. small saucers or butter dishes
• strips of thin metal
• thin soft wire
• 1 sifter
• 2 pails
• muller and pestle
• several pieces of surfaced wood about 12 inches square.

With a flat table to work on, running water or a pail of water handy, a box to receive waste plaster-of-Paris and cement, the proper environment for color cement is set.

GALVANIZED IRON WATER TRAYS can be made by taking a three-inch by seven-inch sheet and cutting a two-inch strip off of one end, reserve for making scrapers and other useful tools. Cut the remaining metal into three rectangular sections for trays.

To make the trays, lay one of these pieces over a strong box with an even edge and hammer into tray shape as shown in the accompanying plate. The corners should be bent so as to make the trays waterproof without soldering. A wooden mallet should be used for hammering the metal as a metal hammer may cut the metal.

MOLDING CASE. Several pieces of board hinged together with one series of edges coming so that they will rest evenly on a flat surface, will produce an adjustable case to use in making molds. A strong cord will keep it in place. A strip of metal (tin, brass or iron) may be used as a cylinder, the circumference being pressed in and tied to conform to the dimensions of the object to be molded.

MIXING PADDLES. Paddles for mixing plaster or cement can be made out of firm wood strips and handles shaped to fit the hand.

INCISING TOOLS. A nail hammered into a piece of firm wood and the head snipped off with nippers then sharpened with a file or emery stone until it is a tapering wedge point. Nut picks may be filed down slightly for this purpose. Two or three points of varying widths will be handy to have, particularly when some of them disappear occasionally as all small tools will.

SCRAPER. A piece of barrel stave or heavy wire bent like a croquet wicket with a wire fastened from end to end is particularly convenient where a number of clay or plasticene tiles are to be produced. For class use two strips of wood are fastened to the bench, the desired width separating the strips. Between these strips a piece of strong paper should be laid and the clay or plasticene pressed firmly onto it between the strips. The scraper will shave the surplus clay if it is moved along so that the wire rests on the wooden strips. Measure off the six-inch or eight-inch squares, cut across with a knife from strip to strip and remove the squares by sliding the paper out. This will give a smooth, even surface on which to model or incise designs.

THE OTHER ITEMS OF EQUIPMENT all have their part to play as follows:

• 2 large spoons—For handling plaster and cement.
• 1 large file or rasp—For occasional use on the tile edge.
• 3 pieces of glass—On which to cast tiles.
• 2 table knives—For paring molds, etc.
• 1 palette knife—For working color into cement.
• 1 bristle brush—With which to oil molds.
• Small modeling tool—To use on clay and plasticene.
• Nut picks—For incising.
• ½ doz. small saucers—In which to mix colors.
• Thin soft wire—For cutting molds.
• Sifter—To sift cement and color for glazes.
• 2 pails—In which to mix cement and plaster.
• Muller and pestle—Grinding mineral colors with cement.

It may be unnecessary to add that the old axiom “A place for everything and everything in its place,” will do wonders toward keeping the temper sweet, and a good temper is a most necessary ingredient for producing good cement handicraft.

	CHAPTER 2 The Making of Plaster Molds

THE SUCCESSFUL USE OF PLASTER is such an important part in the making of color cement tiles and pottery that as a preliminary step or auxiliary to the cement craft it should be well accomplished by the student before using the cement. It is not at all difficult and for those who have not used plaster, there awaits an interesting medium for all forms of plastic applications or adaptations. Our concern with it will be in the making of successful molds for the producing or reproducing of our cement tiles and pottery, but a whole book could be written upon the making of plaster objects. The uses of plaster form a large industry and many art objects are produced in plaster for many forms of applied art.

PLASTER IS SENSITIVE to moisture, and should be kept in a dry place. If plaster does not set within a short time it probably is old and even if it does set in time it will have a tendency to pulverize. It is always safer to purchase an entire sack than to purchase a small lot from the hardware dealer, grocer, or druggist, for the chances are that his plaster has been exposed in a bin so long that its strength has vanished. This is mentioned because instances have been known where trouble in cast making was traced to just such conditions.

ON RECEIVING THE SACKS OF PLASTER AND CEMENT the tendency will be to let contents remain in the sacks. It will be found much more convenient and economical to empty the sacks into a small barrel or box to which a cover has been made. A tin tray under the box or barrel will catch all waste that may drop around the edge, preventing the material from being tracked over the floor. A nail or hook on the side of the barrel for holding the ladle or spoon used for taking out the plaster will enable you to find it when you need it.

THERE ARE VARIOUS GRADES OF PLASTER, but the best for this purpose is molding plaster. The plaster should always be kept in a good dry location.

TO MIX PLASTER SUCCESSFULLY for molds observe the following directions: A bucket or pan large enough to contain the required amount of plaster needed should be used. Then half the water for the amount of plaster used should be poured into the bucket. Sift the plaster-of-Paris through the fingers into the water, until the water absorbs it no longer. This can be determined by small portions of the plaster remaining on the surface. Then stir the whole mass slowly with the mixing paddle until the passage of the paddle through the plaster leaves a channel which closes up slowly.

IT IS THEN POURED PROMPTLY into the center of the space on the glass prepared for the plaster tile so that the poured plaster gradually spreads from the center toward the corners and edges filling up the spaces and coming up the sides to about one-half inch height. Jarring the table or a slight shaking of the glass will cause the plaster to settle very level as well as causing any bubbles in the plaster to rise to the surface and break. Care should be taken that the plaster is not too thick before being poured. This stage of the proceedings requires one having their wits alert, and discussing Futurist art or any other topic may result in “try, try again.” If the plaster appears too thin more plaster should be added until it is the proper consistency.

After the plaster is poured it should set for about half an hour (varying according to the dryness of the atmosphere) before any attempt is made to remove it. Meanwhile all buckets, paddles, ladles, etc., containing plaster should be cleaned while the plaster is soft and easy to remove.

WHEN THE PLASTER MOLD IS READY TO REMOVE, a table knife slightly inserted between partitions and carefully pryed will cause the parts to separate. A most important part of casting molds and the using of the plaster molds is the oiling. All parts of the molds to come in contact with fresh plaster, cement or concrete must be thoroughly oiled or greased to prevent them sticking to each other. If wood, glass or metal is used with plaster, cement or concrete, remember to oil or grease such surface before pouring the plaster or cement on it. If you do not, you will have to use a chisel and with discouraging results.

The best way to oil the surface is as follows:

GLASS—Apply salad oil with brush or cloth removing as much as will come with the palm of the hand.

PLASTER BARS AND MOLD should first be soaked in water ten or fifteen minutes to prevent drawing the moisture out of the fresh plaster or cement. Wipe off surface moisture with soft cloth, and replace with oil, before using for molding. If oil is left thick or in brush streaks, it will leave its influence on the surface of the casting.

WOOD—A smooth-surfaced wood should always be used, and oiled well.

A good grease formula for all surfaces is as follows: Three parts paraffin and one part tallow, melt and add one pint of kerosene. This is applied with a brush.

AS AN EXPERIMENT PROBLEM for the use of plaster so as to become familiar with its use, we will proceed with the casting of a simple flat plaster tile.

Taking a piece of glass, smooth board, marble or oil cloth, brush the surface with a little salad or lubricating oil, or linseed oil. There should be no free oil on the surface or streaks of oil as such will cause an uneven surface. When using glass it is possible to insert a diagram or pattern of the shape underneath on a piece of paper as a guide to the bars or retaining walls of the mold. These retaining bars or walls may be of various materials. Strips of wood or plaster are excellent and strips of linoleum, metal and even glass are used. If four pieces of wood about ten or twelve inches long and one and one-half inches wide are used they can always be adjusted to fit any dimension from twelve inches down, by being placed as shown in the diagram.

TO OIL THE RETAINING BARS, brush the surface to come in contact with the plaster and then hold the wood in position over the diagram below, using modeling wax or clay to keep it in position. The clay of course should always be in position on the outside of the wood and should never be in the space into which the plaster is to be poured.

PLASTER HARDENS SLOWLY IN COLD WEATHER and hardens rapidly in a warm temperature. Salt added to plaster will cause it to set more rapidly and to harden more firmly. No exact proportion can be given—just a little sprinkled in a pan of plaster will cause it to set more rapidly.

DIFFERENT PLASTERS SET AT DIFFERENT PERIODS. As has been described before, casting plasters can be secured in quick-setting, medium-or slow-setting mixtures. Medium-setting or slow-setting will be found to be good average mixtures for use.

TO RELEASE THE PLASTER TILE after it has hardened (generally a half hour will insure the hardening action as being completed), the bars can be released and the tile gently lifted at one corner will cause it to come apart from the oiled surface. If glass is used the glass can be placed upright and the separating of the tile from the glass can be watched as indicated by the moisture suction disappearing as the tile is gradually separated. If oilcloth is used the tile can be turned over and the oilcloth peeled off easily. This of course is necessary only where any sticking occurs, for most times the tile will separate easily. If sticking does occur it is generally some fault of the oiling for it needs only one or two little spots overlooked to cause considerable trouble as the plaster will stick to any part that has been skipped in the oiling.

Plaster dries rapidly and will dry in the sun more rapidly. When plaster is damp it can be scraped or carved easily. Temperature and the age of the plaster affect its drying periods.

LARGE TILE MOLDS should be strengthened by having burlap strips or wire imbedded into the back while the plaster is soft. This creates a stronger layer than where plaster alone is used. Wood strips should not be used for backing plaster unless thoroughly dried as otherwise it causes cracking by its shrinkage, and it is best not to use it for reinforcing.

TO CORRECT FAULTS IN PLASTER CASTS use a little of the plaster scraped from the back to fill in holes or defects. If a corner or portion is broken off, gouge a hole or cavity so that a little plaster mixed and placed on that section will become firmly connected. As it hardens, a little of it can then be scraped with a knife to connect correctly with the surrounding parts or surface.

A SECOND PRACTICE PROBLEM is to take the plaster tile and incise a line pattern in the surface. To make the incising easier, dip the tile in water and then trace the design previously prepared onto the plaster. Pressure alone on the paper with a pencil will make an indentation on the plaster that can be easily followed in the incising.

THE DESIGNS FOR INCISED PATTERNS are best where the lines enclose a shape. The parts are more comprehensive and confusion of the lines will not result if simple outlines are used. In the chapter on Design, line patterns are shown that are adaptable to incised work.

TO INCISE THE PATTERN take a nail point or nut pick or other metal point and shape the point on a grindstone or by the use of a file so that each incised line will have a tapering side. If any undercuts are produced the cast or plaster that is poured into it will become locked and refuse to separate.

The tile is next immersed in water, taken out and after the water is absorbed, a brushing of oil is given to it.

A PLASTER TILE IS MADE MORE DURABLE if it is dried and given a coat or two of shellac before it is used for molding plaster or cement. Otherwise repeated brushing of damp plaster with the oil brush will gradually wear the edges and details of the mold away.

TO MAKE A CAST FROM THE PLASTER MOLD, it is surrounded with the retaining bars after they have been oiled and held in position with the modeling wax or clay; this time they are placed firmly against the sides of the plaster mold.

THE CAST OF OUR FIRST EXPERIMENT now becomes the mold for our second practice problem as the mold is always the part that produces the cast. The cast in turn may become a mold for another cast.

TO SEPARATE THE CAST FROM THE MOLD the bars are removed and a knife edge is pressed between the parts to separate them. Care should be taken not to become too anxious and force the sections apart before the cast has dried or they will cause it to break. If it refuses to come apart easily when completely dry, a little wooden wedge tapped into the crevices in one or two places will cause it to part easily. Sometimes plaster flows over the sides of the mold and binds the edges together. On removing the mold and cast from the retaining bars, examine it to see if any plaster is binding it and if so remove it.

IF THE PARTS ARE ABSOLUTELY SOLID it is because the incising was not properly done and the lines interlock somewhere and the only thing to do is to break them apart and correct the faults and try again. Sometimes when interlocking tiles are separated the faulty parts have fragments of the opposite part attached in the defective parts showing where the faults are located.

THE TWO PLASTER TILES SHOULD BE RETAINED for they can be used in casting plain cement and color cement tiles in various finishes. When they have completely dried they should be given two or three coats of thin shellac, a day apart, on the surface only, which will make them good durable molds for future use.

CASTING IN THE ROUND is more difficult than flat casting or bas-relief work and while the making of plaster molds for vases and bowls is given particular attention in the chapter on Cement Bowls and Vases, directions for casting objects in the round will be given here.

AS A GOOD TEST PROBLEM take any small object or toy and, if it is wood, oil it well. If it is porcelain or glass it will not need to be oiled. A simple form, animal or bird, can be made in modeling wax or clay to be used as the original or model from which to make a mold. The best objects are those modeled in broad surfaces with but little detail.

PREPARING FOR CASTING. The equator or half-way mark should be marked on the surface of the object, as one-half of the mold should be made at a time. Instead of one-half, one-third is often used on round objects to permit easier release of the molds. Mold divisions when possible should follow corners of objects.

THE FIRST SECTION of the mold is made by placing a layer of clay along the division lines on the object which have been indicated as division lines for the sections of molds. Sometimes the object can be laid on the table or on glass and the plaster poured around it up to the half-way line as shown in the accompanying plate. In this method a strip of linoleum or metal can be placed around it to make a retaining wall for the plaster.

AFTER THE FIRST SECTION is cast, the model is removed from the plaster and if the plaster has risen past the equator it should be scraped back and indentations or “keys” made in the plaster portions that are not those producing the parts of the model. The model is replaced in its hollow and the entire surface of the mold that is exposed is oiled, including the sides of the metal, linoleum or whatever is used as retaining walls. Plaster is again poured for the second half after which it is permitted to dry before separating the mold sections.

OILING. It must be remembered that the molds must be oiled after each casting as each pouring absorbs the oil. All surfaces coming in contact with the next pouring of plaster must be oiled to cause separation.

POURING. A hole must be cut in the molds to permit the plaster to enter. Air holes leading upward as shown in the engraving are scraped upward out of the molds to permit the escape of the air; otherwise air bubbles may be formed in the plaster causing defects.

TO HOLD MOLD PARTS TOGETHER tie a cord or wire around parts. Notches cut on corners or edges of molds to hold the tieing cord will prevent them from slipping. Molds should fit closely together. If for any reason they do not, the crevices can be filled with modeling wax as a temporary filler. The best results are obtained, however, from perfect molds and it is a saving of time to make a mold over if it is not perfect in the first casting.

RELEASING CAST. After the plaster has set long enough to harden, the molds are opened by gentle prying or tapping with a wooden wedge. Often an obstinate cast is released by placing the mold over a stove or flame for a few seconds. This causes the steam formed in the mold to separate the mold from the cast.

CEMENT BOWLS AND VASES are made by pouring thin cement into the molds and rotating the mold and pouring out the surplus cement. After a few minutes another layer is poured in and the operation repeated. This method is explained more fully in the chapter on Bowls and Vases.

	CHAPTER 3 Plain and Incised Cement Tiles

A KNOWLEDGE IN MIXING CEMENT is the next step necessary in Color Cement Handicraft. The steps necessary toward mixing cement are simple, the main point being that the cement should be fresh. The student is cautioned to test the freshness of cement by seeing that no caked or hard lumps of cement are contained in the sack mixture. As formerly explained the cement should have a smooth, slippery feeling when passed between the fingers.

NEAT CEMENT is the term applied to cement mixed with water without the addition of any sand or gravel. Neat cement produces a very smooth surface and responds to reproducing every change in the surface of the model. It should be used on the surface only and not for the entire tile or pottery. If used without any sand or gravel, it is termed “too fat,” and has the fault of cracking sooner or later. Therefore neat cement is always backed up with a concrete mixture.

CONCRETE is a mixture of sand and cement, gravel and cement, or rock and cement. In all instances where such a mixture is made, the two parts should be mixed dry before any water is added. Only enough should be mixed to meet immediate needs as it is not best to use cement that has stood so long that it has commenced to harden.

TO SECURE A VERY FINE SMOOTH SURFACE for tiles or pottery the cement should be used neat. It must be sifted dry through a fine sieve and enough water added to make it of easy working consistency. Then a mixture of two-thirds gravel or sand and one-third cement with water added may be used on the back of the tile or the inside of a vase and possibly again lined with a mixture of neat cement.

Cement or concrete can stand for an hour or two and again be used by adding more water and mixing thoroughly. This cannot be done with plaster and should be avoided with cement or concrete. If chemical action has commenced and the cement has partly set, it naturally will have lost much of its strength for second use.

A CONCRETE MIXTURE of one part cement and two parts sand or gravel will give good strength. The sand or gravel must be clean. If it contains any vegetable matter or other sediment, it should be avoided. To test your sand quality put a four-inch layer in an ordinary quart jar, fill with water within three inches of the top. Cover and shake well. Then permit the sand to settle. If the sediment or loam which remains at the top of the sand is one-half inch or more, the sand is not fit for use in concrete.

CEMENT MIXTURES ADAPTABLE TO VARIOUS USES are given below. These may be used for backing and reinforcing large problems, in garden pottery, garden furniture or walls.

Cement and sand mixed dry first, then with water. The gravel is mixed wet with other mixture and thoroughly combined.

Builders use the Rich Mixture for columns and high stresses, and where water tightness is necessary.

Standard Mixture is used for arches, for tanks and sewers, and for machine foundations.

The Medium Mixture is used for piers, sidewalks, and heavy walls.

The Lean Mixture is used for walls, foundations and for unimportant work.

THE FIRST PROBLEMS IN CEMENT should be the casting of cement tiles without the use of color. As a beginning problem set the retaining bars around a six-inch square space and mix a neat mixture of cement and pour into the space so as to make about a quarter-inch layer. After this has set for about fifteen minutes pull some of the neat cement up the sides with a putty knife or strip of cardboard and then pour in the remainder of the tile concrete mixture of one-third cement and two-thirds sand. This will result in a tile with the top and sides surfaced with neat cement. The surfaces of the bars and the glass or other under surface have of course been properly oiled previous to the pouring.

BEFORE PROCEEDING WITH TILE MAKING it may be necessary to make a number of plaster bars to use as retaining walls. These are made as follows: Two strips of wood one-half inch to an inch thick laid parallel on a glass or other smooth surface that has been greased with oil. The distance between the strips of wood should be about ten inches, as the length will then serve for producing eight-inch tiles or any size under this dimension. The edges of the wood facing inward should always be oiled, the wood strips are held in position by small lumps of modeling wax pressed firmly into the outer edge of the wood so that it attaches it to the surface of the glass. This will leave a channel between the two wooden strips into which the plaster is poured. The two ends of the channel may be stopped with blocks of wood or blocked with wax or clay. As soon as the plaster is poured into the mold it should be evened by running a straight strip of wood or metal over it spanning the width of plaster. Run this back and forth to trim off the surplus, so that the plaster will have an even thickness when removed from its bed.

TO REMOVE THE PLASTER first remove the wooden strips and then tap the layer of plaster lightly on the edge with a hammer. This will loosen it. Then with a T square and sharp nail mark off bars five-eighths inch wide and also bars one and one-quarter inches wide. At least twelve bars of each width should be made. After drying for three days the bars may be sawed apart with any sharp saw, care being taken to hold the saw within the groove made by the nail. The edges of the bars may be further smoothed if necessary with a knife or file.

STRIPS OF WOOD WITH SURFACED SIDES can be used in the place of plaster bars and if oiled will release very easily from the plaster when used as retaining walls.

TO MAKE AN INCISED TILE in plain cement proceed as follows: Roll out clay or modeling wax to about one-half inch thickness and cut to the desired size of tile. Cover this smooth surface, place a design which has been made on thin paper and trace with a pencil. The paper should be held so as not to slip and the result should be a slight indentation of the design on the clay. These lines are then incised over with the incising tool to the desired depth, care being taken that no over-hanging edges remain on the edges of the incisions. The incisions should have sides slightly sloping inward and if the tool is correctly shaped it will produce such lines.

THE DESIGN should be planned to be at least one-half inch from edge and simple in construction. Avoid a tangle of ever crossing lines. A geometrical arrangement dividing the square into pleasing spaces will produce the best results.

Place the tile on a level surface and take four bars of the one and one-fourth inch plaster strips or wood, soak in water for fifteen minutes, wipe dry and oil. Now place the four bars so that the inside edges are against the wax or clay tile and fasten so that they are unmovable with modeling wax. The bars if placed with one end projecting past the bar meeting it at right angles permits their adjustment to any size tile under ten-inch dimensions. Onto this pour plaster-of-Paris, pour into the center letting it run toward the edges forcing all air ahead of it as it enters the incisions. Level off surface and remove the plaster cast from the mold as soon as it has hardened.

TO RELEASE THE PLASTER CAST first remove the surrounding bars and lift the plaster tile off the clay. The plaster tile will have the design in relief on the surface. If any clay is adhering to these relief lines, it is evidence that there are overhanging edges and such edges should be trimmed with a knife before the next step. The next step is as follows: After plaster tile is dry put it in water for a few minutes, then oil the surface well. Place back in the bars and repeat previous operations excepting that this time a cement mixture is used instead of plaster. A mixture of neat cement should be used half way up and permitted to remain for five minutes before the concrete (one-third concrete, two-thirds sand) is poured in for the remaining half.

IN MIXING SAND AND CEMENT it should be remembered that they should be mixed together thoroughly while dry before any water is added. After the cement has been poured into the form, if it is to be used for floor or wall purposes, four small squares of cardboard should be pressed into the exposed cement which is the back of the tile. This should be done about fifteen minutes after the cement has been poured, when it is not too soft.

The tile may be removed after it has remained in the form for twenty-four hours. A thin cement mixture of another color may be made and brushed over the tile and the surplus removed, leaving the last color only in the incisions.

AN INTERESTING VARIATION is produced by cutting away the clay or wax between the incisions of the pattern to the depth of one-half inch or less, making a mold of this tile and in turn casting a concrete tile. The result will be a surface with relief section and low spaces, the relief being concrete and rough in texture.

These low spaces are then filled with a colored cement of another color, or neat cement, and brought to the level of the relief surface. Such a tile secures a pattern adaptable to tile walks, or any surface which is subjected to wear, in that the design is not only a thin surface layer, but a thick portion of color that will not disappear with the wearing of the surface layer.

A SIMPLE METHOD OF MAKING TILE MOLDS is to cut a design from a thick piece of cardboard or sections of a design, and glue these in proper position to carry out a design arrangement. These pieces should be cut with tapering sides so as to permit of proper “draught” or releasing conditions when the plaster cast is made for mold purposes.

The pieces of cardboard should remain glued until dried to avoid the moisture of the soft plaster moving the parts around.

WITHOUT THE USE OF COLOR a number of pleasing and varying textures can be secured with plain cement, as the gray color of the cement has an artistic quality, and it is well to become well grounded in the use of cement before combining color with it.

SEVERAL WAYS OF USING PLAIN CEMENT FOR TILES beside those already given are explained in the following descriptions. These are termed Traced Cement, Burnished Cement, Scraped Cement, Concrete Tile, Cement and Concrete Tile, Glazed and Dull Cement Tile, Glazed Relief Line Tile.

THE TRACED CEMENT TILE is made by pouring a half-inch mixture of concrete (one-third cement, two-thirds sand) into a mold made with the usual retaining bars of any desired dimensions. Over this concrete mixture a layer of about one-quarter of an inch of sifted neat cement mixed with water should be placed. At a certain degree of hardness this layer of neat cement will yield to a slight indentation or traced outline. This condition can be tested by touching the edge of the surface with a pencil point to see whether it is too hard or too soft. A good plan is to pour the mixture in the evening and it is generally in right consistency to work upon on the following morning. The surface should be nearly hard but still sensitive to pressure with a point.

HAVING PREPARED THE DESIGN on a piece of paper about the weight of business writing paper, the design is placed on the surface of the tile and kept in the same location while a blunt, soft lead pencil is traced over the pattern, pressing firmly to create a good indented line in the cement surface. The design for this work is best where the pattern is easily expressed in lines or outlined forms. The forms can be increased in strength by rubbing the pencil on the outer edge of the lines to be slightly modeled in separate appearance. When the design has been completely gone over, the tile is placed in water for several days, after which it is dried and a thin coating of color wash (see chapter on Surface Finishes) may be added to it which will further the pattern by coloring the traced lines.

THE BURNISHED CEMENT TILE is produced by casting a similar tile to the one made for the Traced Cement Tile and proceeding in the same manner, excepting that the spaces between the forms are burnished smooth with the dull pointed pencil or a smooth small stick. This results in some parts being burnished or pressed down while others remain in slight relief. A change in this is also produced by scraping the smooth surface off between the lines in certain places instead of burnishing it. This results in parts of the surface being of a different texture and also of a little different color, as the scraped parts are different in both these respects to the cement which has dried and remains untouched on the surface.

A SECOND BURNISHED TILE EFFECT is to pour a layer of neat cement first in the mold and a concrete mixture last. When this is hard enough to remove, and still soft enough to work upon (the neat cement layer having been in the bottom will dry with a dull finish and not a glaze finish as when flowed on as a top layer) it should be removed and the design traced upon this neat cement surface. If a leather tool or smooth hard point is used, certain parts as desired can be worked upon, smoothed down or pressed in, through the paper which will create a change of surface texture.

THE SCRAPED CEMENT TILE is where either the top neat cement or bottom cement layer has the design in line or form scraped out of the cement, the entire design being produced without a plaster mold being used. A sharpened nail or nut pick will make a good scraper and this scraping and pressing is done on the cement surface direct and not through a paper as in the two previous problems. This direct method of working upon cement surface is considered more thoroughly and more extensive applications made of it in the chapter on Carved and Modeled Cement.

THE CONCRETE TILE. Varying finishes may be secured in casting any cement tile by the kind of aggregate used with the cement. A rough irregular small crushed rock will give one kind of texture, while a round small white gravel will give another and each change will present different effects. Without going into extremes of finishes or having too many changes in the surface of a tile, pleasing effects can be secured by one to three changes of texture secured by putting different mixtures in different parts. This may be done by mixing and applying with a brush or spoon the different mixtures into the mold, placing the mixtures each in their proper section of the mold. The whole is then covered with the backing mixture resulting in the surface pattern appearing with the changes after the tile has been released from the mold.

Where a concrete mixture is to appear rough in texture, the sand or gravel and cement should be mixed dry, just enough water added to cause it to mix up to a damp consistency so that it can be shaped with the hand. This can then be put in the mold and tamped slightly with a block of wood to press it in true contact with the surface of the mold. This will result in a porous, open texture, producing good contrast with neat cement parts that have been previously placed or are to be added.

THE CEMENT AND CONCRETE TILE is made with plain cement producing added interest to the design by the two textures or surface finishes that occur between cement and concrete. The design for such a tile is best where the parts are separated either by an incision or a relief line. The plaster mold should therefore present separate portions, some of which can be considered for the cement parts and others for the concrete parts.

By mixing neat cement until it is of a thin mixture, the mixture can be placed on the mold wherever wanted by dripping it from a brush. Care should be taken in the use of a brush with cement that a wiping stroke is not used as such a stroke will remove the oil from the plaster surface and cause parts of the cement to stick to the plaster.

After the cement has been placed, a concrete mixture is made and poured into the space up to the desired height to produce the necessary thickness. This will at the same time fill in the remaining surface spaces of the tile.

THE GLAZED AND DULL CEMENT TILE is produced by filling in with clay or glued cardboard bits cut to shape, those parts that are to be glazed gray cement. Do not use modeling waxes or artificial clays for this part as the oil or grease in them will interfere with the glazed cement adhering to the surface in the final finishing.

After the cardboard or clay is dry a layer of neat cement is poured in, and backed with the usual concrete mixture. After the tile is released, the cardboard bits or clay is removed and cleaned out, the surface under it is roughened with scratched lines and the tile is put in water for an hour. The spaces are then filled with a mixture of neat cement and permitted to harden in a shallow tray of water.

TO MAKE GLAZED CEMENT SURFACE it is important that these steps be watched:

A bloom or chalk-like powder often comes on the surface of tiles, but will disappear within a short time and need not cause any anxiety.

GLAZED RELIEF LINE TILE is made by casting either a neat cement tile or a concrete tile with a relief line design and then mixing a neat gray or color cement glaze and putting it onto the surface. The tile is shaken in a level position until the entire surface is entirely covered leaving a thin layer of the glaze in the spaces between the lines as well as slightly on the lines. The tile is set in a shallow layer of water to harden.

OTHER VARIATIONS IN TILE EFFECTS can be made by combining these methods and with the use of color in these different methods described, unlimited avenues are opened to the worker in color cement. It should be remembered also that most of these methods of surface treatment are also possible in other forms beside flat or tile surfaces. The student should know these methods of working with plain cement and concrete as they are the foundation of successful Color Cement Handicraft.

	CHAPTER 4 Making Vases and Bowls

MAKING VASES AND BOWLS is a little more complicated than the making of tiles, but by following the directions carefully it will be found that once the process is worked out, it can be easily repeated.

FOUR DEFINITE OPERATIONS are necessary to produce a bowl or vase and they may be termed as follows:

THE FIRST STEP, making the original model, is as follows: With clay or modeling wax build a form of the vase or bowl desired. The inside need not be considered; that is, do not make the form hollow but build it solid. Care should be taken to see that the contour is even and alike when viewed from all sides. A templet cut from metal, wood or stiff cardboard, will help in securing perfect contour if moved around on the outside and corrections made accordingly. A false neck should be added onto the solid form and part of the bottom of the mold scraped so as to leave a rim or edge on the bottom. The form is then ready to make a mold from it.

ANY VASE OR BOWL CAN BE DUPLICATED in cement by making a plaster mold from it. The inside of the bowl should be filled with sand or wadded paper and a false neck built over the mouth with clay or modeling wax. If the surface is glazed it need not be oiled before casting, but all dull or rough surfaces should be oiled.

THE SECOND STEP, making the molding case, is as follows: Take the model (clay or vase to be duplicated) and place it upon an oiled glass or other smooth surface. Marking off about one-third of its diameter, build a narrow strip of clay or wax on two sides from top to bottom. This ridge or wall should extend far enough out to meet the molding case or metal strip, and the two walls of clay and the metal or case should be made proof against the plaster running out anywhere, when it is poured into this well. After the plaster is set, the clay strip can be removed from one side and the exposed plaster edge is oiled after two keys have been bored into it with a pointed metal strip (see working plate). The removed strip is then built along the next division of the model and the case or metal used for retaining wall is moved into new position and a second third of the molding case is made. To make the third or last piece of the mold the two first sections are retained in position (always boring keys and oiling exposed edges), the case or metal wall again placed in position and the plaster poured into the opening. The plaster should not be too thin and if a little is poured into the bottom and allowed to set before pouring the whole amount, it will not be forced out through the bottom. Of course all openings must previously have been stopped with clay or wax.

TO STRENGTHEN A MOLD strips of burlap or wire screening can be imbedded in the plaster while it is soft. This makes a durable mold capable of withstanding much handling.

TO MAKE THE MOLD FOR THE BOTTOM the three sections are turned upside down (the model still being in position) and the plaster parts all being oiled, a ring of clay is placed around the bottom so as to make a cup shape into which the plaster is poured.

THE THIRD STEP is the most important part as the mixture or “slip” for the pouring is important. The first mixture should be neat cement and water and should be rather thick, for if too thin it will not adhere to the walls of the mold. When the neat cement is ready it should be poured into the bowl about half-way full. The bowl is then rotated in a horizontal position gradually downward so that the surplus cement slip will pour out of the mouth back into the pan or container in which it was mixed. Then after a half-hour or so another mixture of slip should be rotated. This mixture should be composed of a one-third cement and two-thirds sand mixture and be thinner in consistency. If the bowl is large and the walls need to be thick a third and fourth layer may be necessary.

THE LAST LAYER OF SLIP can be of neat cement which will finish the inside with a smooth surface. When working with color the first rotation and the last may have color added to the slip which will result in a color finish on the inside and the outside of the bowl or vase.

THE FOURTH STEP or releasing the mold, should occur the second or third day after the pouring has taken place. This elapse of time depends all upon weather conditions. In summer cement dries more rapidly and not so well. In winter the hardening is more slowly accomplished but more perfectly.

THE DRYING OF CEMENT is best when it occurs gradually. Never place cement in the sun or use artificial heat to force it. Checking, cracking and breaking will surely result if this is done.

For this reason the tiles and pottery made with cement should dry gradually in the shade but not in a draughty location.

To release a vase or bowl from the mold, the cords are untied and the plaster mold parts opened. The cement cast, if successful, will separate from the mold without trouble. The ridge that may have been formed by the groove where the plaster parts have come together can be scraped off and smoothed by rubbing the finger tips over the surface. The surplus part of the neck can be carefully scraped away and after the vase has dried out of the mold for a day it can be put in a bucket or tub of water to harden for a few days or a week.

TO FINISH A VASE it is removed from the water, permitted to dry well, the surface is brushed clean and it can then be waxed or surface finished as described in another chapter of this book.

A RELIEF DESIGN ON A VASE SURFACE requires care in making the sections of the mold so that the vase cast will pull out of the mold without breaking. If the molds are made in three or four segments there is little danger of trouble but wherever there is relief surface or lines on the surface, a two-piece mold is sure to result in the breaking of parts.

DIFFERENT TEXTURES IN GRAY CEMENT can be secured on the surfaces of bowls and vases by using almost any of the processes described in the previous chapter for tiles.

IN ADDING COLOR TO DIFFERENT TEXTURES of cement in Cement Pottery the color or neat cement can be added to the oiled surfaces of the plaster molds before they are tied together preparatory to the pouring. In this instance, however, the divisions of the plaster molds should be planned so as not to break through the designs. If a continuous design motif is essential, the only way to correct the break will be to touch in the disconnected parts with the right color or mixture after the parts of the mold have been placed together just previous to the pouring in of the slip for the first rotation.

THE MAKING OF FLAT BOWLS simplifies the rotating problem and in many shapes the slip can be placed and directed with the use of a brush. After the last slip has been added to a bowl, a design can be added with a brush by using a different color, placing the color slip in the center of the inside portion of the bowl. This can also be done on the outside surface of any bowl or vase, creating a change and surface enrichment.

VASES WITH SQUARE SIDES should be produced from plaster molds which have the connecting lines coming on the corners. In this way the casting lines that always show to some extent on the cast surface when it is removed from the mold, will occur where it will be easy to remove them and if a little does remain it becomes a part of the corner.

If any incised lines or relief parts are on the sides of these square formed vases, a separate piece for each side will be necessary in the plaster mold.

A GLAZED FINISH can be produced by rotating a bowl or vase in a mixture of neat cement that has been well sifted and placed in a pan in a thick enough layer to permit the bowl or vase to be turned in it without the sides scraping the bottom of the pan.

WHERE LARGE RELIEF SURFACES are to be produced and undercut surfaces molded, it is then necessary to use glue for the molds. This requires skill in handling. For those who wish to produce molds for such work the following is given:

After modeling the surfaces or figures in relief, if they are to be used on garden pottery, book-ends, vases, etc., or any design that has undercut surfaces, it should be covered over entirely with a one-half inch layer or blanket of wet clay or modeling wax. If the modeling has been done in clay it should remain overnight without the usual wet cloth over it, before placing this second clay layer. If wax is used the clay layer can be placed over it without waiting. Deep sections should be lightly filled with clay to reinforce the one-half inch layer. Two or three nails should be used to hold the original firmly to a board base. A little plaster-of-Paris should be poured around its base to help make it firm.

Over this clay blanket lay a strip of clay along the highest part or equator of the surface, so that the surface is directly in line with the equator. Place a casing around and fix so that plaster can be poured, and a rough casing produced of one half. Remove the clay strips and with a pointed piece of metal bore several holes or “keys” in the exposed edge of the plaster. Oil this edge and cast the second half.

Before pouring the plaster a clay cylinder should be placed at the top to form a hole for pouring into and a second hole near it for an air escape.

After the plaster is set it will be found that a casing or shell is produced which when placed over the original model (the one-half inch clay blanket having been removed) will leave a space around the entire original model.

The next step is to prepare the casings and pour the glue into this space to produce a mold of the object and its immediate surface.

A few pencil marks are made on the outside of the casing and carried onto the table or board base to check up its relation when it is replaced. These marks are very necessary.

The casings are then given two coatings of shellac and wood alcohol (one part alcohol, three parts shellac), and when dry are oiled well or greased with axle grease. Shellac is also applied to the original model whether clay or plaster. Plasticene or similar wax need only be oiled slightly.

Replace the cases so that the two halves come together closely and so that the marks on the outside lower edge correspond correctly with the marks on the table. Stop the cracks on the casing with clay dipped in plaster and bind over the casing in the same way (or with the use of cords) to prevent the glue from floating the casing.

THE GLUE IS PREPARED as follows: White fish glue or gelatine glue is washed well in water. Put in dry can, placing it in second pan of water and boil until creamy in consistency. When the finger can be dipped into it without burning, the glue is poured into the casing as follows:

A funnel of clay or wax is roughly made and the glue poured into the opening of the casing, filling the space between the model and the plaster casing.

Let stand for twelve hours. Remove casing and cut the glue shell along the half-mark made by the equator division, cutting from the under side through at one stroke. The glue can be lifted (as it will give) so as to permit cutting from underneath. To cut from the outside will not produce a clean cut.

With French chalk or talcum, chalk the inside of the plaster casing well over the shellac and fit the glue shells back into each half. Then with a solution of powdered alum and water (two teaspoonfuls in one-half cup of water) brush the entire inner surface of the glue to harden the surface. Let stand for one hour.

IF CEMENT IS TO BE USED, the glue must receive two coats of white lead or varnish and left to dry two days. When plaster is used no white lead or varnish is necessary.

Cement should be used thin and a thin layer produced by pouring into this mold and revolving it so that a coating will stick to the surface. After setting for twelve hours more is added and again revolved until the desired thickness is produced.

Where the object is not to be hollow the cement is poured in solid and left until hard enough to remove the casing and glue shell.

This sounds complicated but it is no harder than the usual recipe and if you can’t follow a recipe or be interested in its result, then there is no hope for you in Color Cement Handicraft.

A DIAGRAM ILLUSTRATING GLUE MOLDS is shown at the end of Chapter Two, on The Making of Plaster Molds. A little study of this with the above directions will make the process clearer.

	CHAPTER 5 The Use of Color in Cement Tiles

SUCCESSFUL COLOR IN CEMENT WORK is dependent entirely upon the use of mineral pigments in dry powder form. The lime action in the cement will nullify and disintegrate any color of a vegetable or chemical source so that no hue remains.

A LIMITED RANGE OF COLORS is therefore presented to the worker in Cement with which to secure results, but the list of colors described in the following paragraph is after all an elaborate one when compared with the few pigments with which the primitive and aboriginal potters produce most beautiful results in their wares.

PICTORIAL OR REALISTIC DECORATIONS ARE NOT DESIRABLE as Color Cement decoration and it is hoped by the authors that those who follow the technical direction of this book will be in harmony with the applied design principles set down in the last chapter; and that their color cement productions will be such that it will add correct line, form and color to this new handicraft. This will enable its growth among the art handicrafts to be without handicap or prejudices resulting from its use in incorrect design or application.

THE FOLLOWING COLORS ARE POSSIBLE in mineral colors for us in Color Cement: Black, Brown, Red, Dull Yellow, Blue, Green.

A Color Scale and Mineral Colors are as follows:

THE SUCCESSFUL USE OF COLOR IN CEMENT depends entirely upon the true proportion of color to the cement. No exact rule can be quoted as colors vary in quality in different localities. Experimenting only can solve the correct proportions. Also, anything that will nullify the action of disintegration upon the color by the lime in the cement is desirable. The Petroma Cement Colors made by the American Crayon Company of Sandusky, Ohio, fulfill these requirements for the craftsman, and will aid in successful schoolroom results, avoiding loss of time and waste of material.

COLORS MAY BE GLAZED, MAT OR DULL FINISH according to how and when it is placed on the cement tile. Each finish requires different treatment and the easiest is the Dull Finish.

THE DULL COLOR FINISH is produced when the color is dropped or placed into the mold and concrete or cement is used as a backing. This results in the color drying in the mold with a dull finish next to the plaster mold surface and is exposed when the cement casting is released from the plaster mold.

THE GLAZED COLOR FINISH is more difficult to produce successfully and is secured only in that color that is placed onto tile or pottery surfaces after the cement surface has partially hardened. A tile design or pattern may be cast in a mold and after it has come out of the mold it is dried for an hour and then placed in water. If the surface to receive color has been roughened or lines scraped into it when first released from the mold and the cement slightly soft, the color will adhere even more surely. We know that metal craftsmen often roughen the surface of metal where enamels are to be placed and fired in, to insure more perfect attachment, and a similar treatment to the cement will do likewise for the cement color. When the cement tile has been removed from the water and surplus moisture shaken off a little plain neat cement is placed on the surfaces to be colored and to this the color in thin paste form is dripped from a brush. No back stroke is possible without injuring the finish. Finish each section and then leave it alone.

A SAFE WORKING METHOD is to place the tile in shallow water to avoid any part becoming dry while the color is being applied. A pan or shallow dish will serve the purpose.

THE MAT FINISH is produced the same as for the Glazed Finish excepting that the tile is placed in water immediately after it is removed from the mold and placed there for a few minutes only. The surface is treated otherwise similarly to the glazed process and this results in the color being dull in finish.

HARDENING IN WATER should be done with all tiles and the dull and glazed finished tiles should be set in a pan of water without letting the water reach the decorated surfaces.

A COLORED SKETCH should be made in every instance where color is to be applied to cement.

MATERIALS FOR MIXING COLORS are as follows: Two sizes of small sable-hair brushes, a palette knife (or putty knife), several small dishes, a spoon, a fine-mesh sieve, and a piece of glass.

TO MIX THE COLORS proceed as follows: Place a little of the desired color on the glass, to this add dry cement reducing the color intensity to the desired strength. Portland cement being gray will do this harmoniously. To this add a few drops of water until the color is of the desired consistency.

The color should always be tested on a tile surface and dried in the sun to determine final color, adding color or cement to the wet mixture to correct the color. Where a tint of color is wanted a white cement should be added instead of Portland cement.

To produce a plain surface color on tiles, the desired quantity of color is mixed and strained, to eliminate all coarse particles. The mixture may be sifted while dry or strained after the cement has been added.

THE USE OF WHITE CEMENT should be limited because white cement is not as durable as gray cement and because its setting qualities disappear as it becomes older more rapidly than gray cement. If perfectly fresh it can be used with good results and produces a more brilliant color when mixed with the colors than when gray cement is used.

TO APPLY THE COLOR either in the mold or to the surface of the object after it is removed from the mold, the color should be applied with a brush.

AS A TEST COLOR PROBLEM use an incised pattern plaster mold and the colors may be planned for the incised tile as follows: Working from a color sketch, mix up colors to match and after the plaster mold has been water soaked it should be oiled by dabbing the brush up and down on the surface. If the brush is stroked it will not leave enough oil on the surface and the color will stick to the tile. Next drip the cement color from a brush with a shaking motion. The various colors are thus placed in each of the partitions of the mold and after drying for fifteen minutes is backed with a layer of plain cement and sand and allowed to set.

When the tile is released it will contain different colors between the incisions and a thin wash of an additional color may be added to fill the incisions.

COLORS CAN BE MIXED one with another while dry or when wet to produce other shades. Violet will be produced by the mixture of mineral orange and ultramarine blue.

PLAIN SURFACED TILES MAY BE COLORED by pouring in a thin layer of color combined with neat cement and then backed up with a concrete mixture. Mottled and variegated color surfaces may be secured by first spattering or dropping drops of another color into the mold before the color mixture is poured in. Or the plain cement or concrete tile can be removed and covered with a color layer which will be dull or glazed in finish.

A PLAIN TILE TO BE APPLIED WITH COLOR should be placed in water immediately on being removed from the mold, and allowed to remain there for a quarter of an hour, before applying the color. When taking the tile out of the water do not let the fingers come in contact with the surface to be colored. Let the tile stand a few minutes to drain, before applying the color. Then a thin layer of neat cement mixed with water is applied. Next place a spoonful of the color upon the surface of the tile, slightly shaking the tile while level, then pour off the surplus color as it overflows the edges. If bubbles occur the surface should be recoated for the bubbles will break in the drying, producing a defect. To prevent bubbles, the color should be stirred with the spoon slowly so as to avoid the arresting of air which produces the bubbles. The point of a pin will often help to dissolute the bubbles if used immediately after the surface is coated. When satisfactorily coated, place the tile carefully in a tray and add water until it reaches a little more than half way up the side of the tile. Be careful that water is not splashed or dropped on the newly coated tile, for this will ruin the surface and necessitate doing the tile again. The tile should remain in this water for four or five days, water being added when it has become absorbed or evaporated.

TO COLOR AN INCISED DESIGN the plaster cast from the original becomes the mold for the color cement tile. The plaster, having become thoroughly dry, is shellaced with one or two thin layers of shellac and after drying for one or two days is ready for use with color cement.

It is then oiled well but not so that surplus oil remains on the surface. A dry brush will be good to use for removing surplus oil. The color having been mixed to harmonize with the previously prepared color sketch, one of the color mixtures is taken up with a brush and dripped with a shaking motion onto the correct area, which in an incised design is divided into spaces. If a drop of color falls where it is not wanted, take a clean brush and pick the color out of the space, after which a little oil should be brushed carefully into the space to renew that which was removed with the misplaced color. If any color falls onto the back of color already placed do not worry over it as it will not appear on the finished surface.

ANY COLOR NEXT TO A FILLED SPACE may overlap the previously filled space as only that color touching the plaster surface will be visible when the tile is removed from the mold and is finished.

AFTER COVERING THE ENTIRE SURFACE WITH COLOR let it remain for half an hour before backing it up with the concrete mixture, as otherwise the weight of the concrete may force gravel particles through the thin color deposits and mar the face of the color design.

TO COMPLETE THE TILE remove after two days, and place in water after the edges and slight faults have been corrected. It should harden in water for several days and then dry in a cool place after which it can be waxed or finished in other ways.

ANY OF THE PREVIOUS PROBLEMS described in the methods for producing tiles in plain cement can be carried over into this chapter and color added to the texture finishes in cement and concrete and many interesting finishes developed.

OLD COLOR AND CEMENT or dried cement color should not be used. Mix up only enough color for immediate use as any color not used fresh after mixed with cement cannot be used again and should be discarded.

	CHAPTER 6 Color Cement Relief Tiles

TO BEGIN A RELIEF TILE, a model should first be planned on clay or modeling wax. A pencil pattern is first made on paper and this paper is placed over the layer of clay or wax and a pencil tracing will produce an indented pattern of the subject on the clay or wax underneath.

TO MODEL THE SURFACE a wooden modeling tool, such as is used by sculptors, or a leather modeling tool or even small whittled pieces of wood can be used. In producing raised portions the clay or wax scraped to produce low parts can be used and care should be taken not to produce too great a relief as a tile design should not appear detached.

AVOID UNDERCUT SURFACES or overhanging edges on the finished model as this will result in locking of the cement cast with the plaster mold and breaking of the tile before it can be removed. A general checking over of the different parts before the plaster cast is made will avoid many of the overhanging parts going through as they can be easily located and corrected.

TO CAST THE PLASTER MOLD the clay or modeling wax is surrounded with the retaining bars and as the clay or wax needs no oiling the plaster can be mixed and poured into this mold. A slight jarring of the table or surface on which the mold is placed will cause the plaster to settle, producing a level surface and also cause any bubbles to break or come to the surface.

TO AVOID BUBBLE DEFECTS IN CASTING either with plaster or cement the plaster or cement mixture should be poured into the center location of the mold allowing it to spread gradually toward the sides and corners carrying the air in the grooves and low spaces, forcing it toward the edges. Once the surface is covered in this way the remainder of the mixture can be poured in more rapidly.

TO CORRECT BUBBLE DEFECTS that appear on the finished plaster or cement casting, scrape some of the plaster or cement from the back or sides where it does not matter and repair the flaws by pressing it into the holes. Where cement is repaired this way it should be permitted to dry for another day before it is placed into water to harden.

TO MAKE THE CEMENT RELIEF TILE in color the plaster cast made from the clay or wax model should be oiled after it has been shellaced and surrounded with the retaining bars. The color should be then mixed with the cement and water added to make it of a pouring consistency, it is then poured into the mold. After this color has set for awhile the back layer is added of concrete after the color of the first pouring has been carried up so as to produce color on the sides as well as on the face.

WHERE A NUMBER OF COLORS ARE USED the colors are mixed and dripped upon the oiled surface of the plaster mold before it is enclosed with the retaining bars, as the retaining bars would prevent free access to the surface with the brush. After the various colors have been placed, the plaster cast is then placed within the bars and the color being permitted to set, it is then backed with a layer of concrete.

THE CONCRETE BACKING MAY BE COLORED either with color throughout or with a topping of color to give it a finish. If corners are to be rounded or the edges trimmed in any way this color layer should be thick enough to permit trimming without exposing the under layer.

TO AVOID THE COLOR FALLING OUT in color relief work, the following should be observed. When preparing to pour in the backing, observe whether any of the color cement placed on the tile has become too dry. If so, it should be sprayed with a light coating of water or brushed with a brush full of water, and its upper exposed surface slightly roughened so that the backing will adhere firmly. If it becomes dry and smooth the second layer of cement poured onto it will come in close contact but not adhere, and later a change in temperature or jar of the tile may shake a portion of the design loose so that a color fragment will fall out.

TO AVOID COLOR PREMATURELY DRYING, the plaster cast should be placed in water for fifteen minutes at least before the color is placed into it. To permit free absorption of water the plaster tile should never be shellaced on the bottom but only on the sides and the top.

ANOTHER WAY TO MODEL A RELIEF DESIGN is to carve it on plaster direct without making the relief on clay or modeling wax. This method has the advantage of being proof against overhanging edges, though some care must be taken against undercut surfaces.

TO MAKE THE PLASTER CARVED MODEL trace the design onto a smooth slab of plaster of the right size that has been cast on a smooth surface. If a larger piece of plaster than the desired size is used it can be cut down.

TO CUT PLASTER SECTIONS an old saw can be used or several strokes of a knife on the surface until about one-quarter of the thickness has been cut, and a similar cutting on the reverse side, just opposite to the cutting on the first side will enable the plaster to be broken easily. Or by laying it on a straight edge with the line of cutting over the edge, a quick pressure with the hand will snap the two pieces apart.

AFTER THE DESIGN IS TRACED a chiseled nail point, nut pick or other hard edged point is used for scraping the surface of the plaster, modeling it or carving it to the desired shapes. Naturally it will be found that plaster can only be taken off and not added on and that all reliefs must be produced from the surface downward, that is the natural surface will be the maximum height and all variations in the surface produced below that.

BACKGROUND TREATMENTS are produced where a design appears in low relief against a background. The background may be stippled with the tool point or lines scraped or crossed lines used to create interesting background qualities.

TO BUILD UP PLASTER SURFACES, roughen the surface onto which more plaster is to be placed and mix fresh plaster and place it on with a small spoon or with the brush. After this is dry it can be carved or scraped with the tools used in the modeling of plaster.

TO FINISH THE PLASTER CARVING, it is dried, shellaced, and used for casting just the same as the other relief forms described. To preserve casts from receiving injuries to their surfaces they should be wrapped in paper with a card against their face and placed with face toward the wall in a cupboard or shelf, when not in use. Where a mold has been repeatedly used and the shellac become worn, the mold should be carefully dried and the shellac coating renewed.

A CONVENIENT CLAY TO USE for relief work is the powdered fire clay secured in most hardware stores and is the clay used for lining grates, furnaces and similar purposes. This clay is convenient in that only the amount needed may be mixed up for use, leaving the balance of the powdered fire clay always in good condition.

RELIEF TILES DESIGNED FOR FLOOR SURFACES or for wall surfaces are best where they do not contain deep relief as they will not catch dust or dirt and will be better unified with the remaining surfaces.

SPECIAL TREATMENT FOR RELIEF FLOOR TILES is required in that the cement should be compact and clean sand should be used mixed with just enough water to cause the two to adhere to each other and this should be tamped into the mold well up against the face of the plaster tile to pack the mixture firmly and cause it to form into a durable surface.

TO HARDEN CEMENT TILES or pottery they should be placed in water so that the water will complete the chemical action producing the stone-like quality of successful cement work. If the tile is removed and dried and again placed in water it will increase the hardness.

AFTER THE TILE IS HARDENED it is dried thoroughly and brushed well with a brush. It may be waxed or first given a thin coat of shellac and then waxed. Shellac should never be applied until the cement tile is thoroughly dry, as otherwise the shellac will remain sticky.

	CHAPTER 7 The Majolica Tile