Poly-Optic® 1420 Clear Casting Resin


Poly-Optic® 1420 Clear Casting Resin is a two-part, liquid polyurethane resin that cures (RTV) to a water-clear, Shore D85 plastic. It cures to a tough, impact and heat-resistant plastic that can be polished and machined and is used extensively in prototyping applications. Heat cure (150°F - 180°F) is required to achieve optimum physical properties. When cured at room temperature, the result is a brittle, glass-like casting.

Vacuum and/or pressure casting techniques are recommended for this product. Cure inhibition can occur when casting this resin in tin-cured silicone rubber molds – use a platinum-cured silicone rubber mold if working with silicones.

WARNING: This product contains Phenylmercuric acetate (CAS 62-38-4), a chemical known to the State of California to cause reproductive harm. For more information, go to www.P65Warnings.ca.gov


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Technical Specifications

Mix Ratio by Weight:
Shore Hardness:
Pot Life:
15 min.
Demold Time:
8 hr. @ 150°F / 30 min. @ 175°F
Cured Color:
Mixed Viscosity:
250 cP
Specific Volume:
26.3 in³/lb
Specific Gravity:
5.3 %
Tensile Strength:
7,900 psi
Elastic Modulus:
171,500 psi
Flexural Modulus:
250,000 psi
Flexural Strength, 5% Strain:
12,600 psi
Heat Deflection Temp.:
Max Exotherm:
Demold time varies with thickness of casting and the amount of Poly-Optic Part X Accelerator added. The thinner the casting, the longer the demold time. Shrinkage in polyurethane resins is caused by gelling while hot then cooling.

More Information

Material Calculator

Technical Bulletin

Safety Data Sheet - Part A

Safety Data Sheet - Part B

Kit Components
Poly-Optic® 1420 Components
6-lb kit includes: 4 lb of Poly-Optic® 1420 Part A (~2 quarts)
2 lb of Poly-Optic® 1420 Part B (~1 quart)
24-lb kit includes: 16 lb of Poly-Optic® 1420 Part A (~2 gallons)
8 lb of Poly-Optic® 1420 Part B (~1 gallon)
120-lb kit includes: 80 lb of Poly-Optic® 1420 Part A (~10 gallons)
40 lb of Poly-Optic® 1420 Part B (~5 gallons)