Answer: Liquid medical silicone rubber is typically available from 01 to 80 durometers. Durometer is a measure of the indentation hardness of a material. The procedure for determining indentation hardness of a polymer material can be found in ASTM D2240. There are twelve different durometer types: A, B, C, D, DO, E, M, O, OO, OOO, OOO-S, and R. Nevertheless, type A and type D are the most commonly known and used in the industry.

Type A is generally used for soft and flexible polymer materials and type D is used for hard material. Therefore, liquid medical silicone rubber is generally labeled in type A durometer. Silicone durometer is normally categorized in an increment of 10, but the distribution of the durometer can range from minus to plus 5 durometer from the labeled value; industrial standard allows +/- 5 durometer that includes +/- 2 potential test error.  

Nevertheless, the durometer of liquid medical silicone may be customized to meet the specifications of individual applications. The hardness of a silicone can be modified by changing the crosslink density, filler concentration, or both.

If you have any other questions, please email Phayhean Soo directly at psoo@albright1.com.