Re: 2nd coat paint puckered wrinkles

Posted by Dan on November 04, 2005 at 12:43:04 from (66.15.112.136):

In Reply to: 2nd coat paint puckered wrinkles posted by Tim B MA on November 04, 2005 at 10:46:27:

There are two causes for this problem - letting the paint dry too long, or not letting it dry long enough. Let me explain - multiple coats are best applied so they can chemically bond from one layer to the next. This way - it makes the paint just like one real thick layer instead of actual multiple seperate layers. To achieve this, the first coat cannot be allowed to form a hard shell - or it will keep the second layer from chemically bonding to the first layer. Now, this first layer (especially enamel) will take MANY days to weeks to fully dry, especially when applied thick like with a brush. Just because the top of the first coat has a semi-hard shell - does not mean the paint underneath has fully dried. Now, if you apply the second coat on top of the semi-hard paint below - then the top shell of the first coat will start to slide around as the second coat dries (because the paint underneath the shell of the first coat is not completely hardened yet and only semi-firm) - this causes wrinkles.

Now, you could always wait the extended time it takes for the first coat to FULLY dry and harden, then put the second coat on. However - you would need to rough up the first layer (lightly sand) to give the second coat something to really grab onto, otherwise you would just have multiple layers of paint sitting on top of each other and it would flake off easier.

I hope this isn't confusing the way I wrote it. On my tractors, I only let the first coat dry a couple of hours when I apply it with a brush before I apply the second coat. This gives the paint just enough time to thicken up so it won't run, but not enough time that it forms a hard shell on top. If I want more coats, I wait a little longer between coats with each layer (because it will take much longer to dry and to firm up).

Good luck,
Dan

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