IMPORTANCE OF PROPERLY PREPARING SURFACES AND PREMISES
Preparing surfaces is a critical operation. Most problems blamed on products are actually caused by poor surface preparation. Sometimes, these problems show up when the product is applied, but they more commonly occur long after. That is why we emphasize the importance of properly preparing surfaces.
Sealants
Preparing surfaces consists in cleaning them up and removing any old sealant. Cleaning up the surfaces should be done before removing old sealant to avoid water infiltrations in the gap. You will find below a very simple method used to remove old sealant and a few useful tips on how to replace it. The following pages describe in detail the cleaner application methods.
To remove old sealant:
1. Cut the sealant along the surfaces.
2. Remove the sealant and scrape any remaining sealant while making sure not to damage the surfaces.
Note that outdoor wood must be protected before the sealant is applied (paint, stain or protector). When water penetrates into the wood, it can soften up the wood fibers; the sealant can then get unglued.
Also, silicone- and urethane-based sealants can leave impossible-to-remove residues on surfaces. It is therefore preferable to replace these sealants with sealants of the same type because other kinds of sealant will not stay glued to the surfaces. You can, however, remove silicone residues with a specialized chemical stripper if you want to change product.
Finally, if you want to replace a bituminous sealant with another type of solvent-based sealant, a base coat of Polyprep 1 must be applied on the surfaces. The binders of the bituminous sealants are dissolved by the solvents of other types of sealant and turns them yellow.
Adhesives
For the adhesive to work properly, surfaces must be clean, dry and bare.
If the surfaces are not clean, the adhesive might come unglued by lifting off the contaminant (dirt, efflorescent salts, grease, oil, tar, silicone, wax, soot, etc.).
If the surfaces are not dry, the humidity they contain can prevent or reduce the product’s adhesive power. Humidity increases the time it takes for water-based adhesives to dry.
If the surfaces are coated with paint or another product, the adhesion power of these products may not be sufficient to keep the materials glued. In many cases, the adhesion power that is required is higher that a paint film’s adhesion power. Moreover, paint keeps part of the water or solvent contained in the adhesive to be absorbed by the surface. For all those reasons, paint should be stripped off the surface.
Surface preparation consists mainly in removing, stripping and cleaning surfaces. The degree of humidity contained in concrete must also be tested before an adhesive is applied.