Medium-durometer tin-cure RTV-2 mold making silicone

General Information

GI-1220 is a high tear strength, tin-catalyzed RTV-2 silicone rubber, which was designed for casting polyester parts. GI-1220 offers the same advantages of GI-1120 at a lower viscosity. GI-1220 is especially good for molds with deep undercuts and for molds that require flexing for part removal. GI-1220 is not sensitive to inhibition, meaning it will cure at room temperature over virtually any surface. It is easy to mix and de-air, and will cure with only a slight degree of shrinkage. The speed at which the rubber hardens can be accelerated with special activators. Condensation cure two-component silicone rubbers are excellent for most general mold making and prototype applications. They are excellent for casting waxes, gypsum, epoxies and other plastics. GI-1220 is extremely useful for those applications where superior elongation and medium durometer are required.

Typical Properties

Uncatalyzed Compound

Color

Base:WhiteActivator:Blue

Viscosity

Base:30,000–40,000cpsActivator:300–400cps

Mixing Ratio

By weight:100:10By volume:100:10.9

Mixed Viscosity

15,000–25,000cps

Working Time

1.5–2.5hours

Cure Time

16–18hours

Shelf Life

6months

Vulcanized (Cured) Properties

Measured at 7 days, 70°F / 50% relative humidity

Shore A Hardness

One day:157 days:20

±4 durometer

Tear Resistance

95 ± 10ppiASTM D624

Tensile Strength

390 ± 25psiASTM D412

Elongation

475 ± 25%ASTM D412

Service Temperature

-60 to 340°F

Shrinkage

0.10%

Specific Gravity

1.08

Coverage

25.6in³ / lb