McFadyean wrote:
> The improvements in adhesion probably only comes about by the increase in
> surface area that the abrading generates. In which case there would be no
> benefit in a coarser roughening ....
The article I cited actually goes into extreme depth, and mechanical
adhesion is affected by many factors that I, at least, never heard of,
one of which is surface tension. And even solids have surface
tension. It's true that sanding increases surface area, which
increases the force necessary to delaminate. More important they say
is that abrasion breaks the surface tension, and the degree of
abrasion (if needed at all) need only reduce it below its "critical"
surface tension, which is also relative to the surface tension of the
paint being applied. It all has to do with the paint's ability to
"wet" the surface.
Or so they try to explain, with lots of really big words!
Regards,
Fred F.
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