PlatSil® 71-40 Silicone Rubber

platsil-71-40PlatSil® 71-40 is a 1A:5B mix, mid-range hardness, clear platinum silicone mold rubber. Its clarity makes it most useful for prototype molds where seeing the model helps define parting lines and for filling the mold when casting. These molds exhibit long library life, dimensional stability, and no shrink on cure.

PlatSil 71-40 molds are great for casting resin (polyurethane, polyester, epoxy), foams, plaster, wax, soap, and more. Release agents are not typically required to cast these materials. Popular applications include prototyping, model making, hobby reproduction, soap and candle making, taxidermy, and much more.

Pour this rubber as supplied or add PlatThix thickening agent to make brush-on molds.

PlatSil® 71-40 has the highest Shore hardness in the 71-Series. For harder rubber options, view 73-Series platinum silicone rubbers.


Mix Ratio Shore Hardness Pour Time Cured Color Mixed Viscosity Specific Volume Demold Time
1A:5B A40 60 min. Translucent 25,000 cP 25 in³/lb 24 hr.
Accessories: PlatThix Liquid ThickenerPlatSil® 71/73 Part R RetarderSilicone Fluid 50csPlatSil® 71/73 Part X Accelerator


Product Literature: Technical Bulletin Safety Data Sheets | Physical Properties Bulletin | Sealer & Release Agent Selection Guide

Video Tutorials: For 71-Series video tutorials, visit the 71-Series page or the Polytek YouTube Channel.

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