Is it always necessary to use a primer?
Not always. A primer is an intermediate layer used to prepare the substrate and make it tolerant to the adhesive or sealant used. Consult the Technical Data Sheet of the adhesive or sealant you intend to use.
What happens when I apply too much primer and do not let it dry completely?
Primer usually contains solvent. The solvent will have a harmful effect on the adhesive or sealant, leading to loss of adhesion. In addition, the primer may separate during the drying process and delaminate the adhesive or sealant layer.
Why is it sometimes necessary to sand metal even though I am using primer?
In some cases, stainless steel is difficult to bond because of the nature of the surface (rolled, greasy, extremely smooth, etc.). However, stainless steel always contains a certain percentage of chrome. Sanding the surface and allowing the steel to rest for two to three days allows a thin layer of chromium oxide to form on the steel. This is an excellent substrate for Primer M, to which sealants and adhesives adhere very well.
