Cold weather will not permanently harm urethane, silicone or epoxy materials. It can cause these materials to thicken and separate. If you try to use the material while it is too cold, it will not cure.
If you suspect your materials are cold, allow them to reach room temperature (at least 73°F / 23°C) in the containers before opening. Depending on how long the materials were exposed to the cold, it can take several days to bring them up to 73°F (23°C). Pro Tip: During cold winter months, bear in mind how long material may have been sitting in an unheated delivery truck.
Urethane Rubber – Open Part A & B containers and mix thoroughly (3 minutes) with a clean flat edge stirring paddle (different sticks for each Part to prevent cross contamination) before dispensing into a mixing container.
Silicone Rubber – Open Part A and mix thoroughly (3 minutes) with a clean flat edge stirring paddle before dispensing into a mixing container. For 100A:10B by weight systems (e.g. Mold Max™, Smooth-Sil™ series) vigorously shake the Part B container. For 1A:1B by volume systems (e.g. OOMOO™, Mold Star™, Dragon Skin™ series), open Part B and mix thoroughly (3 minutes) with a clean flat edge stirring paddle before dispensing.
Note for Simpact 60A and 85A: These materials may congeal if exposed to cold temperatures. To reconstitute, Part A & B must be heated to 90°F (33°C) then thoroughly mixed to an even consistency.