Alcohol interaction with lacquers?

weird. Did the paint actually come off on to the cotton swab? Strong 91% alcohol can do crazy stuff. I wipe my models down with Poly S plastic prep. Its a mild solution of alcohol and glycol, and takes off grease and dust and does not affect paint. You could try a clear gloss coat and see if the spots disappear, otherwise its out with the sandpaper.

This surprises me too, since I think the MM paints are truly lacquers.  A problem these days is that there are acrylic lacquers, and alcohol might have a bad effect on those, but I was sure Testors clear lacquers are truly just old-fashioned lacquer.  Might you have used an acrylic primer?

The paint did not come up. Though it was fairly obvious that the flat lacquer did start to come up by the change in finish. Don I did use an acrylic gloss coat, over the enamel but under the flat lacquer for the decals. Could that be it? I wouldn't have thought that the alcohol would have penetrated the lacquer to hurt the acrylic.

I ended up getting a hold of the situation with some wet sanding with a very fine grit. I let it dry up overnight and it looks pretty good. I might not do the re-shoot of flat lacquer.

John

PilotSpike

The paint did not come up. Though it was fairly obvious that the flat lacquer did start to come up by the change in finish. Don I did use an acrylic gloss coat, over the enamel but under the flat lacquer for the decals. Could that be it? I wouldn't have thought that the alcohol would have penetrated the lacquer to hurt the acrylic.

I ended up getting a hold of the situation with some wet sanding with a very fine grit. I let it dry up overnight and it looks pretty good. I might not do the re-shoot of flat lacquer.

John

I wonder if the lacquer coat were uniform enough and covered the whole surface.  Also, did you have any masking, where that left an edge that the alcohol might have gotten access to the acrylic at that edge?

Ahh Don is right. Alcohol will take away cured acrylic paint almost instantly. You must have had a uneven laquer coat and the alcohol was able to react with your previous acrylic gloss. Maybe next time just wipe down with warm water and soap? Or try the plastic prep from Poly Scale like I mentioned. Glad you were able to fix the damage!

Yeah, I am very happy with the fix. Don is spot on, I did some masking and know that I did not follow up with any type of wet sanding to knock the edges down. Very insightful Don. Ill have to check out Poly Scale, sounds like a winner.

Yes, alcohol will soften and remove MM lacquers like gloss, satin and flat clear, Dullcote and Glosscote. The white areas are where the paint has built up as it was wiped. There is a flattening agent in the flat clear and that's what you're seeing and why sanding lessened the effect. Alcohol seems to be only slightly less toxic to these paints than lacquer thinner. I found out the same way you did.

Tony

I just remembered something that I had forgotten in my earlier replies. I use methanol fuel in my race car.  Methanol certainly does spoil the finish of a car, even a lacquer finish.  So at least one form of alcohol does eat lacquer. I always used to use the propynol  windshield washing fluids just for that reason over the cheaper methanol fluids. Is there any chance you used methyl alcohol instead of isopropyl?