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This is really a one-and-a-half part question.

I know that when paint is mixed with a solvent or used with a primer, it sometimes wrinkles. As I understand, a key physical phenomena here is a non-uniform evaporation of the primer or solvent that gives rise to different evaporation rates at the paint surface. This can create a non-uniform temperature difference. This in turn can create a thermocapillarity (surface tension effects due to non-uniform temperature distribution) or solutocapillarity (surface tension effects due to non-uniform solvent/solute concentration) effects that wrinkle the paint surface.

So is this a solvent problem or a primer problem? Am I understanding the physics right but the nature of primer and solvent wrong?

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  • $\begingroup$ I'm unclear on what you are asking... the physics you propose appears to attribute wrinkling to non-uniform evaporation of solvent and of primer. So you seem to be implying that the physics is the same regardless? So what confusion is there about their nature? And what do you mean by "solvent problem" or "primer problem"? $\endgroup$ – tpg2114 Jan 16 '13 at 19:11
  • $\begingroup$ @tpg2114 The primer, I understand is a first coat on which paint is applied. The solvent on the other hand is mixed with the paint to reduce it's viscosity. So what contributes more to the wrinkling? The solvent or the primer? I gather where the confusion may have been. $\endgroup$ – dearN Jan 16 '13 at 20:16
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    $\begingroup$ I think that may knock this out of the realm of physics and make it OT unfortunately. Plus I'm still not entirely clear -- you are supposed to let the primer dry completely before painting over it, so there shouldn't be an evaporation differential due to the primer. $\endgroup$ – tpg2114 Jan 16 '13 at 20:31
  • $\begingroup$ @tpg2114 I was not aware that I'd have to let the primer dry completely. forgive my ignorance! :) Having said that I put this question in physics.stackexchange rather than, say, chemistry.SE because engineers (like me) and chemists have a varied perception of things. However engineers and fluid physicists share a commong outlook! $\endgroup$ – dearN Jan 16 '13 at 20:36
  • $\begingroup$ wrinkling occurs when the surface of the wet paint begins to polymerize before the deeper layers do. Since paint shrinks as it loses its solvent content by evaporation, the partially-dried skin contracts together, sliding over the underlying layer of still-liquid paint and the result is wrinkled paint. In fact, this characteristic is deliberately designed into "crinkle-finish" paint that consists entirely of wrinkles. $\endgroup$ – niels nielsen Jan 29 at 23:44