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Adhesion Myths and Reality Part 2

Steven Abbott & Steven Abbott – Mar 9, 2016

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3 Comments on "Adhesion Myths and Reality Part 2"

Steven A Apr 22, 2016

There's an important exception to my statement that roughness (and earlier about mechanical lock and key) has no effect on adhesion. When adhering to paper, board, non-wovens and, as you say, wood, it is possible for the adhesive to wrap around fibres and gain strength. My myth was more about the general perception that roughening gives a large increase of surface area on surfaces in general. As I know little about wood adhesion (I'm a plastic film guy by training) I would still be cautious about statements about sanded surfaces. Sanding generates dust and even a small residue of dust could contaminate the surface so adhesion is being built on sand. What I would encourage because "Adhesion is a property of the system" is that before making general statements about sanding being good or bad, people look at what's going on in their specific system. For example, is the adhesive, for example, actually wrapping around wood fibres, or is that merely my assumption? Has the sanding left a residue and is adhesion improved if the residue is carefully removed? Etc. I like the trick about pre-raising the wood!

vladimyr W Apr 21, 2016

Dear Mike, If you look at older paint systems, the primer was always an oil based system, and also contained red lead which now is banned. I have 80 year old weather boards that were primed with oil based paints, and then have been coated with the more flexible acrylic polymer pains using R&D Polymers. These weather boards have no dry rot. The extension which was primed and painted with water based systems shows dry rot after 15 years. Wood is best primed with an oil based alkyd that has been thinned down a little.