Mix-a-Mold Helpful Hints
1. When mixing large amounts of Mix-a-Mold use a NIOSH certified mask and locally exhausting hood appropriate for the operation. Mix by adding cold water to the powder and do not produce dust.
2. Using cold water tends to slow the set time; warm water accelerates the set time.
3. Having a high water content the mold may appear wet. A smooth molding surface may appear wet, but not have surface moisture present. You could check by lightly blotting with a soft tissue. Proceed with the casting.
4. If the object to be molded is porous, such as plaster or papier maché, be sure to seal it before molding. If the object is glazed or finished, it would already be sealed.
5. Keep small objects handy when molding, such as jewelry, cameos, coins, etc. and use excess Mix-a-Mold for a quick, small mold. Small cereal dishes, shallow cups, a champagne glass, a cut down paper cup, and other small shallow containers would suffice.
6. When using a model with deep relief and undercuts, you may wish to use Mix No. 2 or No. 3, then immediately prior to placing the model into the mold mix, coat the modeling surface of the model with the mix by dipping it into the mix, making sure that all deep relief and undercuts are completely covered. Remove it, inspect it and quickly place it into mold mix until mix is set. Or, using a brush, brush the surface completely and quickly and immediately place the model into the mix until mold mix is set. Do not allow this film to set up before placing it in the mold mix. This procedure may help prevent deformities in the mold caused by air being trapped in the deep relief or undercuts. The trapped air could then prevent the mix from reaching the model. By surface coating the model even if air were then trapped, it would give support to the surface coating film. When set, carefully wiggle the model from the mold. You are now ready to cast.
7. Remember that these molds, though flexible and easy to make, are not permanent. If you wish to make several casts from these molds, you should do so within a reasonable length of time. Having a large content of water which will evaporate, the mold will gradually shrink causing distortion in future castings. If any of these molds are to be stored for later use, be sure to encase in plastic bags or other airtight containers. Storage in a refrigerator in airtight containers would also help.
8. If you find, after making a mold, that the model was positioned incorrectly and touched the bottom or side of the mold container leaving a void in the mold, you may reline the mold. Since Mix-a-Mold will not adhere to itself after setting, it will be necessary to make several small undercuts or flared openings spaced evenly throughout the mold to secure the liner. Mix a small batch of Mix No. 2 and re-pour into the mold. Reposition your model, let it set, then remove the model. Your mold is now ready to cast. This relined mold would probably be for a single casting only.
9. We noted earlier that we would discuss making a two-part mold. It is really quite simple. Using the knowledge that fresh mold mix will not adhere to mold mix which has set, we can proceed as follows. Select two like containers (preferably cardboard type containers that can be later cut) and line with foil, allowing approximately 2” clearance in the bottom and along sides of each container. Prepare Mold mix no. 2 or no. 3 and fill one container. Place the object to be molded face or front side up in the mold mix exposing half of the object. Allow the mold mix to set. Cut small “V” shape notches about 1/4” deep on each side and at each end of the set mold. This will be used later for repositioning the two halves together.
Prepare enough mold mix for the other like container and pour. Pick up the first container and invert it, placing the exposed half of the object into the mold mix just prepared. Wiggle object lightly and quickly in mold mix, then bring the sides of both containers together evenly. You will force a small amount of mix, which you have displaced, out of the container. Allow second mold to completely set, then carefully separate the two molds and carefully remove the object. Allow second mold to dry slightly for a couple of minutes. Then place the two-part mold back together using the positioning notches. Hold together with rubber bands. Now with a sharp craft knife, carve a pouring hole at the base of the molded object. It is now ready to cast. When cast has set, either carefully remove both halves of the mold (if you wish to save the mold) or simply tear or peel away the mold if you are not saving it. Trim the cast while “green” as needed.
In casting molds created by Mix-a-Mold, we recommend Casting Compound. The correct mixing proportions are 3 3/4 lbs. powder (approximately 6 cups) to one quart of water to produce 81 cubic inches in volume or block, approximately 4” x 4” x 5”. This proportion will enable you to estimate the amount of casting mix required for any mold or casting project.
To finish these remarkable castings, we’d like for you to try Rub ‘n Buff One-Step Finishes and Brush ‘n Leaf Liquid Metallic Finishes.
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