Sil-Thix is a unique thickener for most Silicone Mould Making Rubbers. It can be used with both Condensation and Addition Curing Systems. We recommend a maximum of 3% in Addition Cure Grades and 5% in Condensation Cure Grades. Sil-Thix CANNOT be used in M4503 or Ultrasil. We recommend a test for any non Barnes Systems.