Flexible Mold Compound
This is new mold material is much superior to ordinary gelatin (mold glue) and is very easily made. It does not shrink or dry out like ordinary casting gelatins. If made according to directions it will retain all its original qualities indefinitely, and can be remelted when necessary.
FORMULA:
Flake Gelatin . . . . . . . 4 1/2 pounds
Water . . . . . . . . . . . 4 1/2 pints
Glycerin . . . . . .. . . . 9 pounds
Glucose . . . . . . . . . . 1 pound
Denatured Alcohol . . . . . 1 ounce
PROCESS: Place the gelatin in a large container and pour the water over same; then cover container with damp cloth to prevent evaporation. Mix up thoroughly with the hands every ten minutes to keep water evenly distributed, otherwise the bottom will absorb too much water and the top portion will dry out and harden. Replace cloth after each mixing. After gelatin is thoroughly softened, squeeze out all surplus water (if any), and place in double boiler and melt. A few minutes after it begins to melt start stirring and keep stirring until the gelatin is all melted and free from lumps. Then add the glycerin (which should have previously been heated) and stir until blended. Continue to stir until all ingredients are thoroughly incorporated and remove from fire. Now add the alcohol and stir until thoroughly blended with the rest of the mixture. The compound is now ready for use. Do not add water when remelting.
A double boiler can easily be made by using two metal buckets or pans, one larger than the other. Put a few stones in the bottom of the larger container and partly fill with water. Then put mold compound into smaller container and place it in large container. There should be enough water in large container to come up at least half way on outside of small container. The stones are to prevent the small container from touching the bottom and thereby burning the mixture. Leave unused material in container in which it was melted.
HOW TO GET THE ABOVE COMPOUND TO MAKE MOLDS: First select the article you desire to duplicate. Almost all articles can be duplicated, such as celluloid novelties, metal toys, dolls, etc. Articles cast in compositions, book-ends, emblems, etc.
If the article to be cast is very simple, with one entire side flat like a book-end, emblem, or plaque, it is only necessary to lay it on some flat, smooth surface, like glass or marble, face up. Place a frame of wood or metal bars around it, having oiled the object and other parts well; then pour the pliable mold composition over it. However, for more complicated things such as door stops and novelties in forms of dogs, cats, dolls, etc., you will have to make a mold in two pieces.
To make two piece molds, plaster should be used to reinforce the mold. To make good molds you must bear in mind that both this compound and rubber gives under the weight of the casting material. Therefore, some means must be used to hold molds made from these materials in shape. It must be made so that the mold can easily be removed from the reinforcing shell so that the mold may then be removed from the casting without damaging it.
After you have applied the molding composition or last coat of rubber and compound starts to set - spread about 1/2 inch thickness of plaster mortar over it with a trowel, let set and then remove it. For full body molds in two parts - make one half, let it stand until set, cut notches in the plaster shell around the edge that will be spliced to the other half and then apply rubber and plaster to the other half. To prevent the plaster sticking, coat the splice edge of the first half with two coats of ordinary rubber cement.
RUBBER MOLDS
GUTTA-PURSHA MOLDS:
Purchase a sheet of GUTTA-PERCHA, about one-fourth of an inch thick. Cut it about size desired. Soak it in NAPTHA (which causes it to swell), then soak it in hot water. This makes the sheet of Gutta-Percha soft and mushy in appearance, somewhat like a wet rag. Then in this condition, press it against your model, slowly but firmly.
When there are small cavities such as the mouth or eyes of a figure, be sure that you get the rubber all the way in . . . the better you press it, the sharper the mold will be.
Try it on a plaque first, for that can be made in one piece mold. When it is sufficiently pressed, have some plaster mixed and pour it over the mold. This will harden quickly and so hold your rubber mold (Gutta-Percha), in place until it gradually dries out. It will then retain its shape. This plaster shell should always be used to hold mold rigid while casts are being made.
To make a mold of a figure in the round (showing both sides) the mold must be made in two pieces, with shell of plaster to hold them in place, same a described previously.
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