Priming of surfaces to achieve improved adhesion has been employed in industry for many years and is of particular importance in the use of silicone adhesive sealants and 2-part RTV silicone rubbers. Silicone adhesives and some 2-Part rubbers have built in adhesion promoters; with these products the use of a primer will only be required for use with substrates that are exceptionally difficult to bond to. Most 2-Part silicone rubbers will not have any adhesive qualities and the use of a primer will be essential if adhesion is required (see individual product data sheets).

Due to the large variety of substrates any recommendations regarding adhesion and the use of primers can only be taken as a guide, we always recommend thorough testing for adhesion of any system prior to production.

Silicone primers are normally supplied in the form of quick drying solvent solutions and are available in bottle or can packages.

A good primer must have certain properties and sometimes, perform several functions:

It must be easy to apply
It must dry quickly to a uniform dry film (say in less than 30 minutes)
The improvement in adhesion must be demonstrable
Adhesion to the substrate should not be affected over the temperature range of the rubber