How to distinguish fumed silicone rubber and precipitation silicone rubber?

We all know that silicone rubber base can be classified in many ways, such as fumed silicone rubber and precipitated silicone rubber (also called general purpose silicone rubber), depending on the type of silica added (fumed silica, and precipitated silica). We can distinguish them from the following aspects:

The first is the appearance. If carefully identified, it still looks a bit different. Fumed silicone rubber will appear more transparent and shiny than precipitation silicone rubber. If the quality of fumed silicone rubber is good, it can achieve transparency, but the precipitation silicone rubber can only reach a semi transparent state. If the quality of precipitation silicone rubber is poor, it can only reach a white state;

The second aspect is performance. Generally, precipitation silicone rubber will turn white when pulled, and the pulling distance is relatively short, while fumed silicone rubber will not turn white no matter how it is pulled, and it will not break. A good fumed silicone rubber can be pulled to over 700%;

The third is the tensile strength. The tensile strength, tear strength, and elongation of fumed silicone rubber are better than those of precipitation silicone rubber;

Fourthly, in terms of service life, fumed silicone rubber has high-strength product characteristics and can be used for a long time ( or even permanently) in harsh environments, while ordinary precipitation silicone rubber has an effective life of only a few days or even breaks in severe conditions;

The fifth point is that in terms of price, fumed silicone rubber is definitely much higher than precipitation silicone rubber, and the higher the hardness of fumed type, the more expensive the price is, due to the more proportion of fumed  silica is added; On the contrary, the higher the hardness of precipitation precipitated silicone rubber, the cheaper the price.