Transparent silicone rubber products do not yellowing for a few years, but sometimes in production, some newly baked transparent silicone rubber products look yellow, as if they have changed color. Why do transparent silica gel products turn yellow?

Vulcanizing agent
1. The properties of vulcanizates can be divided into two types: common type and yellowing resistance.
2. Common non-yellowing vulcanizing agent is applied to some non-exposed silicone rubber products which can be used for darker or less demanding colours.
3. Anti-yellowing vulcanizates are used in products which need to be exposed, light and bright, and require high color requirements.

Technological aspects
When transparent silicone rubber products are moulded, the main problems that cause the color of transparent silicone rubber products to turn yellow after moulding are as follows:
1. Die temperature is too high
2. The curing time is too long.
3. After secondary sulfur addition

Quality aspects of raw materials themselves
Sometimes we add anti-yellowing curing agent to the rubber, but the transparent silica gel products still look yellow after forming. It may be that the anti-yellowing ability of raw materials is too poor. For raw materials with poor anti-yellowing ability, the suggestion is to change the materials directly.

Summary:
Although silicone rubber products have excellent weatherability and aging resistance. But sometimes there are yellow silicone rubber products just out of the oven. In order to avoid this situation, the vulcanizing agent should be selected according to the requirements, the temperature of the mould and the vulcanizing time of the product should be strictly controlled in the process, and the yellowing resistance of the raw materials should be paid attention to in the raw materials.