Color Cement Handicraft

by Pedro J. Lemos; Reta A. Lemos

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: