Is your silicone casting rubber remaining sticky, curing too quickly, or are you experiencing other issues during processing? Here you can find the solutions to the most common silicone problems. We have summarised the problem, cause, and solution clearly in a table for you.
Common problems with silicone rubber
| Problem | Cause | Solution |
| 1. The silicone rubber remains sticky. |
a. Incorrect mixing ratio. b. Insufficient mixing. c. Slight surface tackiness. |
a. Weigh both components accurately using a scale (mixing ratio 1:1 by weight). b. Mix both components thoroughly, scraping the sides and bottom of the container. Use the two-cup method. c. Use talcum powder to reduce stickiness. |
| 2. The silicone is too hard or too soft. |
Incorrect Shore hardness selection. |
Choose a different Shore hardness or use silicone oil to adjust the hardness. |
| 3. The mould has many surface air bubbles. |
Air adheres to the object. |
To prevent air bubbles, first brush the object with the mixed silicone rubber. This can be done easily with a brush. Then pour the silicone directly into the mould. To completely eliminate air bubbles, use a vacuum pump and chamber to remove bubbles under vacuum. |
| 4. The silicone rubber does not cure on the surface of my product. | Cure inhibition. |
Addition-cure silicones may cure poorly or not at all in the presence of certain elements such as sulphur or phosphorus. These elements can be present in certain clays or sealants. In that case, use a different type of clay or sealant. You can also seal the clay with a spray lacquer. As a last resort, switch to condensation-cure silicones. |
Having another problem?
Is your specific problem not listed in this article? Our specialists have extensive experience working with silicone rubber and know exactly what to look out for and how to solve the most common issues professionally. We are happy to provide tailored advice and to guide you through the process. You can reach us on weekdays via email, phone, WhatsApp or through our contact form.
