Shellac and Mold in Basement?

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Forum topic by DustyCellist posted 08-23-2014 08:22 PM 2069 views 0 times favorited 2 replies Add to Favorites Watch
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71 posts in 1499 days

08-23-2014 08:22 PM

Topic tags/keywords: shellac pine basement furniture mold shop bench question finishing

I recently built a shop table/lathe stand out of 2×4s with a plywood top. I’m terribly allergic to pine, though, so I sealed all the wood in shellac before assembly.

All was fine for a while, but I went recently to rearrange some benches and to mount a vice on this one, and I’m finding white mold all over it. Of course it’s in a cool and mildly humid basement, but there is no growth on anything else, only on the bench I built. I don’t really think it was in the shellac, because it’s also growing on the ply top. I’ve never experienced anything like this before, and it is startling!

There is plenty of rust around from old toolboxes and such, from my grandparents house which recently was emptied after my grandmother passed away, but I don’t think the mold came with the toolbox or anything of the sort…

Any guesses? Any suggestions?

2 replies so far

View CaptainKlutz's profile


246 posts in 1464 days

#1 posted 08-23-2014 09:15 PM

Hmm. I’m no expert. Only seen mold on shellac twice. IME – Mold only grows on/under shellac when it has been compromised (softened) by vast amounts of water/solvents. Even Zinseer primer/sealcoat will allow mold growth eventually if it stays wet long enough. If this is a recent build, and this is the only piece affected, maybe the shellac was not applied thick enough to seal the wood properly and it is the wood that has absorbed the moisture and is growing through the thin finish?

I’d move it outside, scrub brush it with bleach water, let dry for a couple of weeks, then seal again with polyurethane or marine varnish.

I used a bench with poly in a damp basement for 5 years and even though the wall base trim had mold spots the bench never had an issue.

Best of luck figuring it out.

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View RussellAP's profile


3103 posts in 2256 days

#2 posted 08-24-2014 07:24 PM

You have mold on top of the finish or under it. White pine molds at the drop of a hat. A mild bleach solution with a rag will take care of it if it’s on the top of the finish.

-- A positive attitude will take you much further than positive thinking ever will.

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