Hi guys, I know this is an old topic, but I'm new to the forum & just came across it.Hopefully I can explain what has gone on here & prevent anyone else having similar problems.
Once a car has been painted/lacquered it takes some time for the solvents in the thinners used to "outgas".The solvents evaporate through the layers of paint to the surface & disperse into the atmosphere. (that's why a fresh paintjob still "smells" even after a few weeks, it's the solvents evaporating). Now, it seems the guy lacquered the car (3 coats) & no doubt would have baked it,colour sanded it & re lacquered it again (another two coats) prior to final colour sanding.
What has occured here is that although the car has been baked in the low bake oven & to all intents & purposes seems hard to the touch, the paint is still "out gassing" & will continue to do so for a few weeks.The solvents from the first paintjob won't have fully outgassed & subsequently they've been "trapped" between the first & second paintjobs. Once trapped they will show up as small white dots in the paint as you try to colour sand.
Had the painter applied all 5 clearcoats in one hit, it's more than likely this problem wouldn't have occured. However,assuming it's a 2K lacquer that is used, any more than 5 coats of lacquer used, will start to create it's own problems. Too high a build thickness of paint/lacquer will cause the same problems. Because 2K paints are dried chemically (catalyst used) you'll find that the surface of the paint fully cures & "traps" the solvents in the paint underneath it, as the solvents cannot evaporate through a high/thick build of paint quickly enough to reach the surface before the surface cures fully.Another problem you'll come across with too thick a paint is that as it "cures"it shrinks somewhat, & can in certain circumstances crack or pull out of tight edges.
If you want to add a high build of paint/lacquer to your car, then paint it & leave it for a good few weeks before recoating it again, in doing this you'll even be able to colour sand through the second lacquer job to the first & still be able to cut & polish without seeing the "edge" between the two paint jobs. HTH..........Nigel
ps you guessed,..... I've had my own custom paintshop for 26 years & have taught in auto colleges, oh yeah & I live in Britain & I'm currently putting together a '69 Z28.
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