Are you facing a dilemma like this: how to adjust the hardness of the RTV-2 silicone material obtained through procurement? In order to help you and others completely solve this confusion, we have listed four factors that affect the hardness of silicone rubber. We believe this will be helpful to you.
First, let's understand the knowledge about the hardness of RTV-2 silicone. The hardness range for condensation-cured silicone is typically between 5 and 40 Shore A, while addition-cured silicone falls within the range of 0 to 50 Shore A. Generally, hardness measurement data within ±2 falls within the normal range of error, making it difficult to perceive any difference by touch within this error range.
Factors Influencing:
1. Silicone Oil Ratio
Manufacturers incorporate silicone oil into the production of RTV-2 silicone materials to regulate the hardness of the cured silicone. Generally, the more silicone oil added, the softer the hardness of the silicone after solidification, and vice versa. We do not recommend users to add extra silicone oil themselves, as excessive addition of silicone oil may result in oil marks and a deterioration in performance.
2. Curing Agent Proportion
The permissible range for the ratio of condensation-cure silicone to tin curing agent is from 100:2 to 100:4. However, the standard specification is obtained by testing at a ratio of 100A:3B. When the A part and B part ratio is lower than 100:2, the hardness of the cured silicone may be slightly lower than the standard data.
3. Temperature
The various data of condensation-cure silicone are usually obtained by testing at 25℃/77℉. If the temperature is below 20℃ (68℉), the hardness may be slightly lower than the standard hardness. Therefore, we recommend using RTV-2 silicone in a temperature range of 20℃-30℃ (68℉-86℉).
4. Different Silicone Mixtures
Different models of silicone in the same category can be mixed and cured together, but condensation-cure silicone and addition-cure silicone cannot be mixed and cured together. For example, if you mix 10 Shore A and 30 Shore A condensation-curing silicone in a 1:1 ratio, the cured silicone will have an approximate hardness of 20 Shore A. We do not recommend inexperienced users to perform this procedure. If one truly wishes to modify the hardness using this method, it is advisable to first test the results on a small sample.
Modifying the hardness of silicone may not yield significant or easily achievable results. Therefore, we recommend that you purchase silicone with the appropriate hardness to create molds as the best solution.
