How to determine the quality of food grade silicone products?

Appearance
Color: High quality food grade silicone products have pure and uniform colors, without obvious color differences or impurities. If the color is uneven or there are abnormal color spots, it may indicate that the silicone raw material is impure or impurities have been mixed in during the production process.
Surface: The surface should be smooth and free of obvious defects such as bubbles, cracks, scratches, etc. Bubbles can affect the strength and sealing of products, cracks may be caused by poor raw material quality or improper molding processes, and scratches may affect the normal use and appearance of products.
Transparency: If it is a transparent food grade silicone product, its transparency should be high, and the internal structure of the product can be clearly seen. Poor transparency may be due to excessive fillers or other impurities added to the silicone gel.

Physical property
Hardness: The hardness of food grade silicone products should be moderate, generally between Shore A30-70 degrees. The hardness of a product can be roughly judged by pressing its surface. High quality products should have a certain degree of elasticity and be able to quickly return to their original state after pressing. If it is too hard, it may affect the comfort and sealing during use; If it is too soft, it may cause the product to deform and break easily during use.
Tensile strength and elongation at break: High quality food grade silicone products should have high tensile strength and elongation at break, indicating their good toughness and tensile resistance. A preliminary judgment can be made through a simple tensile test, such as stretching products by hand. High quality products should not break or deform excessively during the stretching process, and can recover to their original state after stretching.
Flexibility: Food grade silicone products should have good flexibility and be able to bend and fold within a certain range without cracking or breaking. The product can be repeatedly bent and folded several times to observe if there are any signs of damage on its surface.

Chemical
Non toxic and odorless: Food grade silicone products should be non-toxic and odorless, and will not release harmful substances to the human body. It can be preliminarily judged by smelling. If there is a pungent odor or peculiar smell, it is likely that the product quality is unqualified and contains harmful chemicals.
Chemical corrosion resistance: Food grade silicone products should have a certain degree of chemical corrosion resistance and be able to withstand the erosion of common substances such as acids, alkalis, salts, etc. in food. You can soak the product in some common food acid-base solutions, such as vinegar, soy sauce, soda water, etc., and observe whether there are any changes on its surface, such as discoloration, expansion, shrinkage, etc.

Usage performance
High temperature and low temperature resistance: Food grade silicone products typically require good high temperature and low temperature resistance to adapt to different food processing and storage environments. Products can be subjected to high and low temperature testing according to the product's instructions or relevant standards. For example, placing the product in a high-temperature environment (such as an oven at around 200 ℃) for a period of time to observe whether it undergoes deformation, discoloration, aging, and other phenomena; Place the product in a low-temperature environment (such as a refrigerator freezer at around -40 ℃) for a period of time and observe whether it becomes brittle or cracked.
Sealing performance: For some food grade silicone products used for food storage or packaging, such as sealing caps, sealing rings, etc., sealing performance is very important. It can be judged through a simple sealing test, such as installing the product on the corresponding container, pouring a certain amount of water, and observing whether there is any leakage.
Service life: High quality food grade silicone products should have a long service life and be able to maintain their performance and appearance for a long time under normal usage conditions. It can be judged through long-term observation, paying attention to whether the product has aging, wear, deformation and other problems during use.