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Starbase101

Sr Member
It is MDF, with a primer coat, sealer primer, then another primer coat, then the gray color coat, and everything is fine up to that point - no cracking. It is the satin clear coat that is cracking up when applied over the gray paint, same painting conditions as when applying the gray paint. It is cracking all over the board, I simply photographed the same area. I had no problems with the cabinet and the backsides of the door and buttons face, it's just the front sides of these last two pieces that will just not take the clear coat as all the other surfaces did. They are sanded down again and drying in the house near a furnace vent for applying gray paint again tomorrow.
 

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Jintosh

Master Member
RPF PREMIUM MEMBER
The green areas crack, the red areas don't crack. This may be coincidence based on limited sample size. ;)
 

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Rogviler

Well-Known Member
Are they all the same type of paint though? When you look on the cans under "cleanup" does it say to use paint thinner/mineral spirits or lacquer thinner/acetone? If they're not all the same then that is most likely your culprit, especially if that last coat is lacquer and the rest are enamel. Been bitten by that one a few times myself.

EDIT: I notice in your previous photos that you were using Duplicolor primers, which are definitely lacquer, and the Krylon paint, at least, is enamel. Even if the clear is enamel, clear coats run a little "hotter", i.e. more solvent, so I'm betting that's what's going on. As for why it's wrinkling in specific spots, that could just be that one of the finishes has been sanded thinner in those areas or there's more of something that the clear is reacting with.
 
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Starbase101

Sr Member
There is cracking in the red marked area of the second image, along the edge.

Primer = Dupli-Color Automotive 2 in 1 Hi-Build Primer
There is no indication anywhere on the can of what base type it is (annoying that so many manufacturers omit this information from their products), and there are no cleanup instructions either. Had to go to the Dupli-Color web site product information page to confirm that this is indeed lacquer primer. There is also a Dupli-Color Sealer Primer applied, which is also lacquer based.

Gray = Krylon Gloss Pewter Gray
Again, the manufacturer felt no need to indicate anywhere on the can what base type it is, but at least this one does say to use mineral spirits for cleanup. The Lowe's web site specifies this as an acrylic paint.

Clear = Krylon Satin Crystal Clear
Again, no bloody paint type mentioned on the can, but cleanup is specified as mineral spirits. This is also indicated to be an acrylic paint at the Lowe's web site.

All the surfaces have been prepped and painted the same way, and none of them have had any problems except the outside/front faces of the door and buttons panel. The backsides of these two parts came out as clean as the cabinet box. Gray has been re-applied this morning, and I'm doing a second coat of gray this afternoon. It will get a few days to cure before trying the clear coat again.
 

Starbase101

Sr Member
Well, today's gray color coat cracked all up so I'm sanding it back down to wood and will use either a Krylon primer, or no primer. What should have taken just a few days to paint is now in its second month.
 

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Jintosh

Master Member
RPF PREMIUM MEMBER
Good call. It has to be some interaction between the paints.

If lacquer is solvent based, and acrylic is water based, then the lacquer undercoat with it's solvent may be eating up the above coats of acrylic paint. Really, even if that didn't seem likely, it still seems to be the only explanation.
 

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Starbase101

Sr Member
After sanding back to bare wood and omitting the lacquer primer, I still got cracking with the Krylon gray paint over the Krylon gray. But, eventually, after paint, sand, paint, sand, paint, etc I finally got a clean color coat. It's got some scratches showing through from the previous layer, so next I'm going to sand this with a higher grit paper for one more color coat before attempting the clear coat.

UVbox38.JPG
 

Jintosh

Master Member
RPF PREMIUM MEMBER
The wood would have absorbed the lacquer at a depth. Removing the paint, did not remove the lacquer absorbed by the wood itself. Eventually, removing the top layer of wood by sanding so much likely fixed the problem.
 

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Starbase101

Sr Member
What's weird is the cabinet box and the backsides of these two pieces all got the same treatment with Dupli-Color primer and none of them cracked. As fate would have it, only the two most visible faces ended up having issues. Anyway, fingers are crossed that another layer of paint to help work out the remaining scratches from coarser sanding of lower layers will hopefully provide enough barrier that a few thin coats of the clear might not crack.
 

Jintosh

Master Member
RPF PREMIUM MEMBER
Which brings us back to my original comment, the wood may have absorbed some moisture at some point in it's life. If it was ever the top surface that was left outside, or someone spilled something on it, etc.
 

Starbase101

Sr Member
Well I still got some cracking when starting with the clear coats again, so needed to do more repairs with the color finish. After multiple attempts I've finally got the front surfaces nearly done. The trick was to dust a few clear mist coats over the paint to "seal" it and then a couple slightly heavier mist coats for the final finish. The door is now done and curing, the buttons panel still needs 2-3 more clear layers built up.

UVbox39.JPG


UVbox40.JPG
 
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