SS4004, SS4044, and SS4120 primers are formulated for use with Momentive Performance Materials RTV silicone rubber adhesive sealants. Momentive Performance Materials one-component products offer primerless adhesion to many substrates. Primers are used to help promote adhesion to difficult-to-bond substrates. For most Momentive Performance Materials two-component products, a primer is required when an adhesive bond is needed between the silicone rubber compound and a non-silicone surface (see table below). All primers are one-component products requiring no mixing and are supplied ready-to-use as easily pourable solvent solutions.