Poly-Fast 72-40 Liquid Mold Rubber

Poly-Fast 72-40 is a dense, medium hardness rubber used primarily for casting plaster, waxes and in some cases, cement. Popular for art foundry, lost wax, bronze casting applications.

This Shore A40 liquid polyurethane mold rubber can be poured as supplied or thickened with liquid Poly-Fast 72 Part D, fumed silica or Poly Fiber. It can be softened with Poly-Fast 72 Part C to make rubbers softer than an A10.

Cured molds may soften with age. For rubber options that will not soften with age, consider Poly 74-Series polyurethane mold rubbers.

This product may degrade with age and should not be considered for molds where long shelf life is required.



Mix Ratio Shore Hardness Pour Time Cured Color Mixed Viscosity Specific Volume Demold Time
1A:10B A40 30 min. Ivory 4,000 cP 20 in³/lb ~16 hr.
Accessories: Poly-Fast 72 Part D Thickener, Poly-Fast 72 Part C Softener


Product Literature: Technical Bulletin | Safety Data Sheets | Physical Properties Bulletin | Sealers & Release Agents Selection Guide


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