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Main => Main Forum => Topic started by: shatteredzman on July 17, 2009, 07:17:14 pm
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I am having a problem with my paint drying with wrinkles. I am using spray paint and it goes on smooth but after about a minute wrinkles begin to form. I have tried sanding with 400 grit and 220 grit sand paper between coats but they still show up. I have tried putting on thin coats as well as thick coats. This is happening on more then 1 piece of MDF. What is causing these wrinkles?
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Did you seal the MDF with some good primer or water/glue? MDF is very porous and may be sucking the paint into itself.
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Did you make sure that it was completely cleaned of any oils or anything on the surface, or even in, the wood?
Did you use a primer?
Are you waiting long enough between coats?
What kind of spray?
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I second the primer remark.
I used spray paint for my final coat, and I would get these wrinkles in areas that were not WELL primed.
Actually, I would get these wrinkles if I didn't prime AND apply a coat of roll on paint. Or if I sanded too much before spraying.
Also, be sure your not using water based primer and oil based spray paint. That could have been causing it for me as well. I never did get to the bottom of why this was happening to me, but I found a formula that worked. 2 coats of primer, 1 coat of roll on, then spray, sanding in between each.
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MDF does not respond well to spray paints if built up to this kind of level as you need an excellent base with several primer coats if you want a gloss finish with the spray. You may do better to rub down and use an alternative.
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A couple of likely causes:
1. You had contaminants on the wood - oil, chemicals, etc. If you didn't sand thoroyghly the surface and use a good primer like KILZ, that is most likely the cause.
2. If you did sand before painting and use a primer, then you likely put too many coats or too much paint on the wood without allowing it to dry completely.
One last possibility, though rare, is that you got a bad can of paint. Most likely, it was 1 or 2.
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Yup, looks like a contaminated surface to me. The steps for a good painted surface are simply: Sand, Clean, Prime, Sand, Paint, Sand. Some paints don't like being sanded, so make sure you use one that does sand or else you'll have to skip the step and take whatever finish you end up with (same with paint).
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I put 3 coats of primer on the MDF and let it all dry over night before I started with the black. After it dried over night I sanded it with 400 grit sand paper and cleaned it with a paper towel and by hand. Since nothing I seem to do is fixing this I will sand it down completely and give it another try today. I did notice that I could see an oily shine in this can of paint that I did not see in any other can.
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Sounds like a bad can of paint.
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any kind of grease or wax will spoil a paint job and cause it to wrinkle. this sounds like your problem. anyone painting something this big should always have a gallon of autobody grease and wax remover on hand. this is the stuff that the pros use to clean cars before primer or paint. any ICI body shop supply store sells it.
Thanks.
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any kind of grease or wax will spoil a paint job and cause it to wrinkle. this sounds like your problem. anyone painting something this big should always have a gallon of autobody grease and wax remover on hand. this is the stuff that the pros use to clean cars before primer or paint. any ICI body shop supply store sells it.
Thanks.
Poorly-mixed paints or those stored incorrectly will also do this as the compounds begin to seperate in the tin. In the instance of sprays shaking usually cures this but if it has been stored in extreme hot or cold it will be no good. I had a tin of exterior weather shield that got left in a cold metal shed during a hard freeze and the colour completely seperated from the solvent leaving a coloured sludge at the bottom and a waxy solvent liquid that culd not be mixed back together.
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From my car-restoration days, I remember the golden rule that if you spray cellulose-based paint over acrylic primer exactly this will happen.
I think cellulose paint is quite rare these days but the problem is still likely to be paint mis-match.
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I bet it's the length of time you're waiting between coats. I think most if not all spray paints are changing due to stupid EPA requirements, and I ran smack into this problem when working on my tron cab. Are you using Krylon by chance? I know for a fact that this brand has the problem as that's what I've used for a long time. If so, did you notice how the caps are shaped differently than they used to be? They have kind of a tapered look now. Read the instructions closely but IIRC you have to apply multiple coats within 5 or 10 minutes or you have to wait over 24 hours.
I started a similar thread I think on klov at the time, and that is what I learned. Sure enough, it was right on. You gotta follow the instructions precisely.
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Most importantly: What type of paint are you using? What type of primer are you using?
Your paint wrinkling is most likely caused by the summer time heat and the paint drying too quickly. If your piece is hot, or you're painting in the sun light you will get this problem. You'll also get wrinkling if you're spraying on a very thick layer of paint.
Best advice would be to wait until it cools down at night, and try again doing very thin light coats. Wait several minutes between coats, or until the 'wet' look starts to go away.
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I bet it's the length of time you're waiting between coats. I think most if not all spray paints are changing due to stupid EPA requirements, and I ran smack into this problem when working on my tron cab. Are you using Krylon by chance? I know for a fact that this brand has the problem as that's what I've used for a long time. If so, did you notice how the caps are shaped differently than they used to be? They have kind of a tapered look now. Read the instructions closely but IIRC you have to apply multiple coats within 5 or 10 minutes or you have to wait over 24 hours.
I started a similar thread I think on klov at the time, and that is what I learned. Sure enough, it was right on. You gotta follow the instructions precisely.
shanman its true that paints are changing rapidly especially in places like california where its absolutely mandatory to change everything as much as possible to lower the vocs.
its also true that vocs arent good stuff. standing over a can of car paint with no mask on if your stupid enough to is terrible. I had to do this one time in autobody class just because the instructor insisted we do that so well never do it again.
but this is going to take a few years for them to work out where they finally come up with something that sticks as well as the old stuff did. For now, ill just keep on checking my respirator to make sure the cartridges arent bad.
Remember how long it took them to come out with something besides R-12?
it was a long time before "freon" came back to your local auto parts store. But it did, eventually.
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It came back with the same setup the old stuff had even. Its a different formula, but 134 is some cold stuff indeed, and supposedly it doesnt eat clouds.
thanks for listening.
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From my car-restoration days, I remember the golden rule that if you spray cellulose-based paint over acrylic primer exactly this will happen.
I think cellulose paint is quite rare these days but the problem is still likely to be paint mis-match.
+1. EXACT same thing happened when I repainted a tractor a few years back, only it was somehting like painting a flat over enamel or something to that effect. I would bet about anything it's a paint mismatch.