Caution: Hard Hat Area

The Mysterious Case of the Exploding Shellac Can

comments (7) November 19th, 2009 in Blogs

Ed Pirnik, producer

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Lesson learned: always check the date of manufacture when purchasing shellac.

Photo: Ed Pirnik

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Remember how your mom taught you never to eat anything out of a bulging tin can? You know, the botulism warning? Turns out it goes the same for shellac as well -- sort of.

This afternoon I found myself in the FHB/FWW workshop during my lunch break. My aim was to use some clear shellac purchased this morning at the local hardware store to finish some walnut and maple picture frame molding I put together last night. I set the can down on my finishing table, broke out a flathead screwdriver and proceeded to pry off the lid when, WHAM, the top shot off like a champagne cork and a shower of shellac droplets filled the air. After a short trip to the bathroom to throw out one of my now-contaminated contact lenses and use the emergency eyewash, I figured I might as well give the moldings a quick coat before setting off to purchase new lenses. Trouble was, my clear shellac was actually . . . brown!

No worries, I thought, I'm sure it's just this particular brand. It'll dry clear. So, now I've got some beautiful walnut moldings with maple stringing that's been stained into oblivion. I'm hoping to use a small block plane to shave off the top layer and get back to clear maple but, who knows!

Oh, and the shellac can? Well, it was manufactured in June of 2005, making it well past its prime.

Has anyone out there had a similar experience with old shellac? If so, I'd be curious to hear about it in the comments section below. As for me, I'll be cursing myself for at least as long as it takes me to plane through my stained maple so please, commiserate away! I could use the laugh.

posted in: Blogs, shellac, exploding can, finishing

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Comments (7)

epirnik writes: Hi professors,

I've been using pre-mixed shellac for years and years and have never experienced anything even remotely like this. Ditto for my colleagues. It was indeed a puzzler!

Cheers,

Ed

Posted: 12:09 pm on December 1st

GrahamPianos writes: I've read that shellac cans have a special coating to prevent chemical reactions with the shellac. Perhaps your can's protective layer was compromised, and the brown color was rust?
Posted: 12:53 am on December 1st

astersia writes: Same thing happened to me with a gallon can of shellac based primer, in the middle of my kitchen. I was wearing glasses, but the kitchen table, ceiling, walls, window moldings and pendant light were not. Alcohol did not remove the pigment, so ended up refinishing the kitchen table. It was right before Christmas, too.
Posted: 9:36 am on November 30th

professorss writes:
ed, pouring insult upon injury. Doubtful the can exploded because of expired shelf-life. Only things in the can are (should be) alcohol and shellac pearls. The shellac itself is inert, safe for kids.

Rather than ask us amateurs why didn't you ask Jeff Hewitt or other contributors at FWW? I'd give my eye teeth to be on the staff and have more or less instant access to renowned experts.

You were lucky to escape without permanent eye damage..

Key point: If you didn't know how to use a tool, you'd probably seek instructions. Apply the same caution to materials used in the shop.
Posted: 1:21 am on November 26th

Anatole writes: Freaky incident. Glad you're OK.

Try removing the funky shellac from your project with a rag soaked with denatured alcohol (the solvent used to dissolve the flakes). That's the nice thing about shellac -- it is removable.

Posted: 9:20 am on November 23rd

epirnik writes: Hi Piffin,

To be honest, when using wipe-on or brush applied stains and finishes, I've never felt any need to use glasses. That will of course be changing after yesterday's events.

By the way, the offending stained maple planed right off! I have yet to exchange that can of shellac, though. Perhaps Monday morning.

Cheers,

Ed

Posted: 9:14 am on November 20th

Piffin writes: Hey ed, Shame on you for not wearing safety goggles or glasses! I tried contacts for a couple months once, and learned that they are fine for vanity, but have no place in construction work. Think of how you would be burning if that were an acetone type product.

Shellac can go back quick in a lot of different ways. For me, old shellac just gets gummy usually and does not want to dry nicely.

But since it is an alcohol carrier, you may be able to dissolve the messed up surface with denatured alcohol and clean it off.
Posted: 8:45 pm on November 19th

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