Primers, general sealants

Primers usually require solvent evaporation and several curing steps before the adhesive or sealant can be applied. Adhesive primers are usually not fully cured during their initial application. They are dried at room temperature, and some are forced-air dried for 30 to 60 min at 65°C. This provides a dry, nontacky surface that can be protected from contamination and physical damage by good housekeeping practices until the substrate is ready to be bonded with an adhesive. Full primer cure is generally achieved during the cure of the adhesive. 

Polysulphide sealants in general have good adhesion to steel, aluminium and glass, usually without a primer for porous substrates such as wood and masonry it is recommended to use a primer. 

Primers for porous surfaces are generally film-forming resin solutions. They perform the dual function of preparing the surface to receive the sealant and binding any friable surface... 

Performance of primers has been studied both in general construction and water-retaining structures.Further information may be found in articles on Selection of joint sealants. Sealant joint design, Paint primers and Primers for adhesive bonding. 

The cure speed and adhesion of an anaerobic sealant can be increased by treatment of the surface with a solution of a primer or activator. Early anaerobic thread lockers were strongly affected by part cleanhness, and degreasing the parts with a chlorinated solvent improved performance dramatically. The condensation product of an aldehyde and a primary or secondary amine, a sulfur-containing radical accelerator, or a compound of an oxidizable transition metal were some of the materials used to activate the anaerobic cure [182] - [184]. Due to the ozone-depleting potential of chlorinated solvents, acetone, alcohols, or hydrocarbon solvents are generally used at present. 

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