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Casting the Mold Block Materials
13. Immediately after the Mold & Casting Compound and Catalyst are mixed thoroughly, hold the mixing container approximately 12 to 18 inches above, and over the Casting Dam. Begin to pour the mixture into the Casting Dam slowly, causing a long slender stream of material to string out from the mixing container. This method is called “Ripping the compound”. Ripping the compound will cause most of the air bubbles trapped in the mixture to be forced out. Over fill the Casting Dam slightly. Fig. 7.
14. With Casting Dam Capping Glass; Mold Release coated side down; center and place the Capping Glass over the filled Casting Dam, and press down gently. Allow excess Mold/Casting Compound to overflow the Dam. Place a moderate weight on top of the Capping Glass to keep it from sliding. Allow at least one hour for Mold & Casting Compoun to harden (cure). Fig. 8.
15. After allowing one or more hours of curing time, or when Mold & Casting Compound feels rigid and tack free, slowly lift capping glass away from what is now the Sculpting Block. Lift sculpting block and retaining dam together away from glasswork surface.. The sculpting block and retaining dam will seem to be stuck together. From the bottom side of the sculpting block press the mold block out of the retaining dam. Fig. 9. & 10.
16. Wash the mold block and all other tools used in this procedure in warm water. Let dry.
17. Use #120 dry sand paper mounted on sanding block to remove excess casting flash from sides of the mold block.
The mold block is now ready for “Glass Facing” one side.
T.E.A.M. LIST
Polyester, Epoxy & Urethane Polymer resins are classified as “Thermal-sets”. They are RTV’s (Room Temperature Vulcanizing). All thermal-sets are Part A & Part B combination materials. All thermal-sets have a “Pot Life”. Pot life is that time the material is in the working stage (”A” Stage).
When working with thermal-set resins; time becomes an important factor. Thermal-sets must be cast or injected before they enter the “B” Stage (begin to gel). “C” Stage is a completely cured (hardened) thermal-set.
Epoxy & Urethane resins are very slow in the A to C process in comparison to polyester resins, or polyester base materials. If catalyst and temperature elements are wrong, polyester resins can gel in a mater of seconds.
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