Silaform silicone putty is a one to one mix material which is excellent for a variety of procedures. Silaform 90 (blue) has a Shore A hardness of 90 while Silaform 70 (purple) is more flexible and has a Shore A hardness of 70. Both materials resist deformation and abrasion normally associated with silicone putty. - Sold in sets - Good strength - Two levels of hardness available Indication for use: Duplicating material Mixing ratio: 1:1 A/B Includes: (1) 25 kg A (Activator) and (1) 25 kg B (Base) CROSS CONTAMINATION can occur: 1.) From fumes while containers are opened simultaneously. 2.) When using the same scoop or hand, to remove material from containers. Cross contamination is evident when base material begins to harden, or hard clumps appear.