Lacquer Crazing

[Ken Casser]

I'm painting 15 small frames (9 x 12" Sanded Poplar 1" x 1" deep) with Black Glossy Nitrocellulose Lacquer. I made them all from the same wood stock, milled the wood the same, sanded the same, etc, etc the same. I'm painting them all at the same time, same conditions, same paint with an Accuspray HVLP system which is working very well for me. Why would two of them have crazing on them? And, it's not crazing everywhere, just in small spots. I tried photoing them for you, but it's not easy photographing black lacquer. Anyway, here are two photos of the same leg on the same frame - 1/2 crazed and 1/2 smooth. I'm still getting wood grain showing through, but figure a couple of more coats should solve that. So far I've got a coat of lacquer black primer and four coats of topcoat on it. What gives?

[Rick Lucrezi]

Cant explain why thats happening but I would like to ask about your HVLP set up.

[Ed Hazel]

How long between coats? I have some nitro that will craz if i try to recoat the next day, unless I give it a good sanding or I apply very light coats.

[Jarrod McGehee]

did you seal the grain? maybe that would help.

[Bob Childress]

Had this happen to me recently and discovered it was too thick a build on the NCL. Lacquer, it turns out, doesn't like to get over 4 mils thick sometimes and will craze. Your 4 coats may not be consistently thick and the thicker parts are crazing.

[Larry Edgerton]

From my experiance one of two things, too thick a build or you touched up the black primer after you did a clear coat.

[Ken Casser]

Rick, ask away!

Ed - 24 hours between coats. From what I've read, I should be able to recoat in 20 minutes, but I let it go longer because I shoot the lacquer at the end of the day and go home. Hasn't been a problem before.

Jarrod - Doesn't the primer seal the grain? Should I be using a Seal Coat before the primer? I thought I could do one or the other. Hadn't thought of doing both.

Bob - you may have it right. I did use less thinner on one or two coats on purpose to see if I could get more paint on it. It's a fine line between to thick and too thin I think.

Larry - I'm not using clear coat - I'm using black glossy lacquer over one coat of black primer. I did need to touch up a couple of spots and did put a little primer over the glossy black, but I don't know if that's where the crazing is coming from.

Next question - Will a coat of mostly thinner solve this, or do I have to sand off the crazing and start over?

Thank you all.

[Rick Lucrezi]

I just got a Lexaire HVLP turbine and a bunch of guns really cheap, I dont know how to use it. I have no way to connect the guns to the big hose, so I tried spraying using a Sata HVLP gun with my comprsesor and I used a ton of product and had a shop full of overspray. I thought it was supposed to be low overspray and keep most of the product on the item being sprayed.

[Ken Casser]

Rick, maybe someone else on SMC can help you with this, but all I can tell you is that I got an Accuspray turbine and gun, and the hose plugs right into the gun, no problem. I get very low overspray and it works great. I think there are two kinds of HVLP guns - those that work with the turbine, and those that connect to a conventional compressor. Maybe all of yours are the latter kind? The thing about the turbine is that it pushes a large volume of air through the gun which (I think) a standard compressor can't do. So the results will be different between the two types of system. I would try turning down the air pressure on your gun, turn down the paint volume, and narrow the pattern if possible, and see if that gets things under control. With my setup, and doing my narrow frames, I have the "pattern" needle open about 1/4 turn, and the "paint volume" needle out about one full turn or less, and that seems to work well. Anything more open than that and I get a real mess. The turbine has no pressure adjustment - it's full volume all the time.
Sorry I can't help more, but I'm feeling my way in the dark as well!

[Bob Childress]

Next question - Will a coat of mostly thinner solve this, or do I have to sand off the crazing and start over?

Thank you all.

All I can tell you is my experience. I tried spraying thinners several times but no joy. Ended up taking the offending table top back to bare wood. () Second round of spraying worked just fine, but I did not have luck getting the thinner to flow the crazing out. Maybe someone else has a better idea.

[Phil Phelps]

I'd think crazing is a reaction to somethng. What did you use as a primer? If you're spraying lacquer, you know not to use an oil base primer? You could use a pigmented shellac or lacquer under coat on raw wood. I'd let it set for a day and sand it and shoot it with Bin. I have made many frames from poplar and usually use Bin as a primer. I've never had this happen in forty years. It's not a loss, just an inconvenience. Good luck and please post results.

[george wilson]

I think there must have been something on the wood to cause the crazing. Many things have much thicker finishes than you have put on. Exactly what could have been on the wood? Do you use silicone spray on your machines?

[Ken Casser]

I sprayed a coat of mostly thinner at the end of the day yesterday and haven't gone to see the result yet, but will let you know.

I would have also thought that something was reacting to the lacquer, but out of 15 frames only four are showing this reaction, and on those four, it's in very small areas, and in different places on each frame. What I mean is that there will be one spot on one frame about two inches in length, and that's all on that frame. Another frame has a stretch of about 3 inches and that's it. I suppose it's possible that they bumped into something along the way, but I guess I'll never know. The primer I used is a proper black lacquer primer supplied by my local paint store (ie not HD or Lowes). I put TopCoat on my table saw some months ago, but no silicone - unless the previous owner did (saw was bought used last Fall. Maybe there was a trace left?

I'll be back in the shop tomorrow and will check the results. If I still see crazing, it's back to the wetordry and repaint.

Thank you all!

[george wilson]

Did you handle something,then pick up the frames with something on your hands? Maybe someone before you did that.

[Ken Casser]

I'm the only one who's been near the wood, and I wear rubber gloves when I work with the wood after sanding to avoid finger oils. I'm also constantly washing my hands as they have to be clean for me to handle the art that I work with. A mistake is always possible, but I work on all fifteen frames at once - i.e. if something got on one of them, it would most likely get on most of them to some degree. I'm thinking that either I laid down one coat too thick, or maybe the room temperature was too cold and just at that critical point, but that would have affected them all, too. I'll have a look in the morning.