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.