Not to mention why and how do I fix it. Doing up an all black guitar for a friend, after putting on the 3rd coat of lacquer I got this blueing on the head stock. It looks like the barrel on my old Hawken rifle. I have 3 coats sanding sealer, 4 coats black lacquer, and as I said a third coat of clear gloss. I'm using the Color Tone Nitrocellulose lacquers from Stewart MacDonald. I've used them before and loved them, everything was working great until this last coat went on. Any explanations of what happened, and how to fix it?
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A light sanding took care of it. The new coat went on fine and I'm back on track. I think it had something to do with that partial coat I put on and then turned away from for a couple minutes. Its the only spot that this happened to and its the only area that I "double coated". It is a cool effect though. I think after this one is done I might try out intentionally messing up the finish to see what I get. With the abalone on the finger board, that oil spill look could make for a really cool effect.
Takes class to make a feature of a screw up, five stars *****
I agree - You learn more by making mistakes......well.....unless it involves parachutes!!! :-)
Yes, it's called "blush" which is moisture trapped under the finish. This occurs on humid days, and black is the worst finish for showing blush. I used to spray black lacquer on pianos for a living, so I'm very familiar with this. What I used to do was substitute a certain percentage of "blush retarder" for the lacquer thinner when mixing paint. On some days, it was so humid, you could put in 100% blush retarder, and it would still blush. In that case, all you could do was stop and wait for a less humid day.
However, you're working with spray cans. I believe Stew Mac or Guitar Reranch or somebody sells a spray can of blush retarder. I think all you would need to do is spray a coat of that on top. You might need to do a layer of blush retarder and then another clear coat. Just follow the instructions on the can. What it does is remelt the finish, then the retarder will dry more slowly than regular lacquer, which will allow time for the moisture to escape. Then, voila, no more blush.
Wow, I can't imagine living in an area that was that humid. But that makes a lot of scene, though I don't see how it happened to only the head stock. But I spray my finish outside and it was about 34 degrees when I went out for that coating. My cans get a good soaking in hot water for about 15 minutes before spraying so it was a warm finish. So I can totally see how the contrasting temps would create moisture under the finish. Perhaps the head stock being thinner is why it happened there and no where else, It would have cooled off faster than the rest of the neck.
I wish you knew what went wrong because honestly i like it lol . to me it looks like water marks . like the wood wasnt dried or humidity etc. or it wasnt cured and sanded before you popped the clear on .
You know, I had started spraying it when noticed something at the tail (accidentally set it on a spot of water after I sprayed it) which I stopped to take care of really quick, then continued with the head stock and neck. But this stuff dries pretty quick. I can touch it without leaving fingerprints after like 2 minutes. Despite that it still needs about 2 hours before its cured enough to apply another coat. So with what you said Eric, with de-laminating, maybe that coat that I had started had dried a little, and I basically began another coat over it after just a couple of minutes instead of hours. I bet that could cause de-lamination.
You know, its kind of cool looking, if I could get that down the entire length of the guitar neck it might work... I'll have to experiment later when its not a guitar that's already been paid for.
All you would have to do is add more stress points. See how that is happening close to the tuners, corners and edges? It might not be physically separating, but there is a lot of stress building up in the coating and you are probably seeing areas of concentrated low/high stress points. Put on a pair of polarized glasses if you have some and look at it under different angles and see how it changes.
I think sand down until the areas don't appear and start over with thinner coats properly cured in between.
You probably need to rub it down with fine steel wool until the halo goes away, then respray. Are you using steel wool between coats?
Looks like a coating may be delaminating from the underlying surface causing the light interference patterns. Like oil patterns on a puddle.