My shellac finish on a 1920s dresser bloomed overnight and I'm stumped

I was finishing up a piece for a client in Springfield, using a fresh can of Zinsser's SealCoat, and the humidity was normal. Woke up this morning and the whole top has that milky, cloudy haze you get from moisture. Has anyone had this happen with dewaxed shellac in a controlled environment?

3 comments

3 Comments

noah_walker164mo ago

Ugh, that's the worst. I mean, I had the exact same thing happen on a table last year, also with SealCoat. It was bone dry in my shop. I fixed it by lightly sanding the haze with 320 grit and then wiping it down with a rag damp with denatured alcohol. It re-liquefied the shellac and it dried clear. Maybe the can itself had some moisture in it?

andrew6934mo ago

SealCoat is dewaxed but it's still shellac, it hates any moisture at all. That haze is basically the shellac turning back into its gummy state. Try a test spot with a cloth dipped in fresh alcohol, see if it melts clear again. If it does, you can fix the whole top without sanding.

jason3282mo ago

Honestly, I'm not buying the moisture theory here. SealCoat is pretty bulletproof once it's fully cured. That haze looks more like bad mixing to me, maybe the shellac flakes weren't fully dissolved. I've seen it happen when a can sits too long and the solids settle weird.