A finishing question, lacquer over lacquer.

[dansnow]

I'm  working on a commissioned project, and ran into something that surprised me. the center feature of the plaque is a 9.5" gear with the 8" dia center recessed half the material thickness with an angle cut. 

Because of the two piece design I was able to paint the center piece without a lot of pain masking it off. I sprayed the wood with 3 coats of black lacquer, letting it dry between coats. Then I glued it together and sprayed the whole thing with clear lacquer. When the first coat dried I discovered the entire surface of the black lacquer was covered with fine cracks, giving it a crinkled texture when the light hits it a certain way. Since a brass plaque is to be mounted in the center, I actually like the look, but I'm curious why it happened. I assumed, erroneously it seems, that lacquer over lacquer would not react this way.

 

Any thoughts?

[Rob Roy]

Seems to be a reaction between the lacquers Dan. Was the first coat perfectly dry when you put on the clear coat??.

Rob Roy.

[Scrappile]

I have sprayed lacquer before and even when spraying the same lacquer over the preceding coat, have had that happen.  I do not know why.  Very frustrating.  Hope someone here knows how to avoid it. 

[LarryEA]

Best I can suggest is do a search for 'lacquer finish checks' and see what comes up.

Maybe one coat dries too fast. Lacquer is more brittle than most other finishes.

[Multifasited]

If lacquer ,ever gets a white haze ,you got moisture between coats ,don't panic respray with straight lacquer thinner will take it right out ,your problem sound like the last coat dried too fast ,was the piece warm ?

[dansnow]

The black dried for at least three days before I sprayed the clear. Same brand. I'd done this before without an issue. Unheated shop, but here in northern CA temps have been in the upper 70's during the day.

 

Got lucky this time, the results are better than if I'd planned it.

[wedo scroll]

When spraying lacquer over lacquer, the thinner in the sprayed layer will always dissolve a bit of the previous layer. That is why you have very tight bonding between layers. The side effect is what you noticed. Not sure what conditions cause it or what to change to avoid it. Maybe taking precautions to have more thinner evaporate before landing on the object - higher air pressure, further distance away, higher air temperatures all could help.

Bill

[DWSUDEKUM]

What was the temperature in the area where you were applying your lacquer.  If the lacquer is too cold it will check, if the piece is too cool it will check.. just a couple of thoughts on the subject.

 

 

DW 

[dansnow]

I think you may have hit it DW, thinking about it, it was a little chilly one morning when I put a coat of clear on. Dang.

[Scrappile]

I've had it happen in warm weather, and in different spots on the same piece.  That is why I try to stay away from lacquer.

[dansnow]

I've been using rattlecan lacquer for over 2 years on my projects and this is the first time I've run into the checking. I like the lacquer because it cures fast. I've had the urethanes and enamels stay tacky for 2-3 weeks before finally curing.

[amazingkevin]

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