Bubbles in lacquer

[Russell Neyman]

I'm an old dog with lacquer, so I'm somewhat chagrined to have to ask. But...

I'm in the process of applying a more-coats-than-it-probably needs finish on a show piece, which is a walnut hollow form. I'm following my usual steps; sanding sealer, lots of fine sanding, application of 2-3 coats of clear, a bit more sanding...you get the drill. Normally, this works perfectly and most of the applications went off without a hitch, but these last few days extremely small bubbles have been appearing several hours after I've applied a coat. What's going on?

OK, here are a few factors in anticipation of your questions and comments:

• it has been incredibly cold here and I'm able to raise the temp in my studio with an electric space heater
• the humidity is pretty high
• I'm using Deft rattle can gloss
• I have not used any solvents to clean the surface during the process

I'm wondering if the wood itself has moisture in it that I didn't detect? Am I simply applying too much finish in too short of time? Could the heater (which is about three feet away) be causing the bubbles? Or is this just another episode of Twilight Zone?

[Wayne Lomman]

Most likely the job is too close to the heater which is causing the lacquer to skin off before out gassing is complete.

Curing at low temperature is best done by warming the job before you start. This may require leaving it in the warm area for some hours or overnight. This way the the lacquer dries uniformly rather than from the outside as happens with externally applied heat after spraying. Cheers

[Russell Neyman]

Wayne, that makes perfect sense. Effectively, the outside surface is curing too quickly. This also might be the result of me applying thicker-than-usual coats, which I probably did. Oh, well, time to sand it back and start anew.