Few original surfaces are ideal for bonding. Priming the surface is a means of transforming the substrate, either chemically, physically or both, into an ideal condition for successful bonding, to ensure long-term performance. The simplest form of priming is wiping the prepared surface with a conditioner (such as Sika Aktivator), which reacts with the surface to provide improved wetting characteristics and more reactive chemical locations.
Porous and rough surfaces require a primer with film-forming properties to re-profile the surface, producing a denser, more even bond.
In some cases, the film-forming primers also prevent plasticizers or resins, present in the wet adhesive, from being absorbed into the substrate as this may cause discoloration or bond starvation.
Primers must always be allowed to dry thoroughly before application of one of the Sika Marine adhesives. If left too long, the primer must be reapplied or reactivated to previously primed areas. Minimum and maximum drying times are given in the Primer Chart for Sika Marine Applications in this manual (see chapter 10). Primed surfaces should be protected from contamination such as dust, dirt, grease, vapors, moisture, etc., until the bond is formed.
Please note that containers of pigmented primers should be shaken prior to use. Ensure that primer containers are resealed immediately after use.
Elastic sealants and adhesives can be applied with low surface preparation to corrosion resistant paints. As long as the paint system is compatible with Sika's elastic bonding system there will be a long term performance of the bond line.