In the previous articles1, we have looked at general concepts for surface preparation and methods for preparing plastics for bonding. In this article, we examine surface preparation for metals.
In plastics bonding, surface preparation is used to increase the surface polarity and improve wetting ability for the adhesive or primer. Metal surfaces typically have oxide layers. These oxide layers are already highly polar and inherently lend themselves to good adhesive bonding. Surface preparation is used to improve bonding to metal surfaces, but the main reason for preparing a metal surface is to improve the durability of the bond, particularly in moist environments.