GT Products 1340 is pourable two-component silicone rubber compound designed for making flexible molds.
GT Products 1340 is recommended for repetitive production of intricate shapes cast in epoxy or urethane resins. It is also used for potting electronic components and protecting sensitive assemblies against thermal shock and vibration.
Because fillers settle during storage, both GT Products©1340 and catalyst 1340 should be thoroughly stirred before mixing together. Use separate tools for mixing the two components to avoid cross contamination. GT Products 1340
base is mixed with catalyst 1340 in a 10 : 1 ratio by weight. Add the catalyst into the base to assure complete dispersion. Mixing may be done by hand with a spatula or by machine. When machine mixing avoid prolonged high speeds to prevent premature cure. Avoid stirring in an excessive amount of air. Complete mixing is indicated by a uniform yellow color.
Base Catalyst
Color White Yellow Specific Gravity 1.27 1.0 Viscosity (cPs) 70,000 1,000
Mixed Viscosity 35,000 Pot Life (pour time) 1.5 hr.
After cure (24 hr @ 25°C)
Tensile, psi: 650
Elongation, % 350
Durometer, Shore A 40
Tear Strength, Die B, ppi 50
Useful Temperature
Range, °C (°F) -60 – 232
(-75 – 450)
Air entrapped during mixing should be removed to prevent voids in the cured product. Deair the mixed material under a vacuum of 25 mm (29 inches) of mercury. The mixture will expand to about four times its volume, crest and recede to about the original level as the bubbles break. Degassing is usually complete about two minutes after frothing subsides.
GT Products 1340 will cure sufficiently in eight hours at room temperature (75°F) to be handled. GT 1340 will reach 90% of ultimate cure in 24 hours at room temperature. For full cure an additional 1-2 days at room temperature or an elevated temperature cure is required.
Typical Cure Times
| 75°F | 24 | hr. |
| 100°F | 95 | min. |
| 200°F | 5 | min. |
GT Products 1340 will remain useful for six months when stored in the original unopened containers at temperatures below 80°F (27°C).
GT Products 1340 is an addition (platinum catalyst) cure system. It will cure in contact with most clean dry surfaces. Certain materials such as butyl and chlorinated rubbers, sulfur containing materials, amines and condensation (metal soap catalyst) RTV silicones can cause cure inhibition. This inhibition will manifest itself as a sticky interface with the substrate. Inhibition can often be minimized by warming the substrate to evaporate contaminates, neutralizing and rinsing, or by the use of a suitable barrier. A sample patch test is recommended.
The above data is based on typical experience and should not be used for specification writing. Suitability of GT-Products 1340 for a specific application should be determined under actual use conditions. No warranty, expressed or implied, is hereby made.
1 June 2001
GT Products inc. 501 Industrial Blvd. Grapevine, TX 76051 Phone # 800-221-0866 Fax # 817-421-1211