Color Cement Handicraft

by Pedro J. Lemos; Reta A. Lemos

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.