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Preparing Mold & Casting Compound
Mold & Casting Compound is made of polyester resins that become hardened (cured) by adding, and mixing in a chemical reaction catalyst (MEKP). The amount of catalyst required to cure the resins properly is relative to the mass of compound. A “Rule-of-thumb” formula is: a ¼ inch line of catalyst per golf ball size mass of Mold & Casting Compound. Do not be concerned that these elements have to be measured with extreme accuracy. They do not. Slightly more catalyst will only cause the compound to harden faster, causing a shorter pot life. Pot life is that time this mixture will be workable. Elevated room temperature will also cause the mixture to harden faster. Thus; colder room temperature, the longer the hardening time. Ideal room temperature should be between 70 to 80 degrees. Since raw Mold & Casting Compound is a whitish gray in color, and Catalyst is red, I have learned to determine the final blend should become an even light pink in color (Liter pink = slower hardening, darker pink = faster hardening).
At the risk of losing large amounts of Mold & Casting Compound later; I will suggest experimenting with small batches of these elements until you become familiar with the color equals hardening time ratio.
12. With tube of paste catalyst; squeeze an estimated amount into the mixing container. With tube of M.E.K.P (Methel, Ethel, Keytone, Peroxide), add ½ of 1 percent by volume to the total Mold & Casting Compound. In this example, that would be three or four drops of M.E.K.P. Fig. 5. Stir both catalysts into the Mold & Casting Compound until the mixture is uniform in color. Be sure to scrape the sides and bottom of the mixing container while stirring. Fig. 6.
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