Old shellac flakes a problem?

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Old shellac flakes a problem?

Postby Chris Lounsbury » Wed Sep 12, 2018 10:46 am

Yesterday morning I mixed up some shellac using the same method I've been using for years now but with less pleasing results.

I am making a "2lb cut" using the proportions on the card that came with the Dewaxed Ultra Blonde flakes which I bought from WoodEssence maybe 4 or 5 years ago. I ground up 36g of flakes in a coffee grinder and added that to 150ml of 99.9% pure Recochem Methyl Hydrate from a brand new gallon jug. Throughout the day yesterday I stirred the mixture every couple hours but now, about 24 hours later, it is still not well dissolved. According to my previous experience, it should be ready to use by now.

What is the most likely cause of my problem? I bought the jug of Methyl Hydrate from a local Canadian Tire. It is the same type & brand I have always used but, could I have a bad batch or contaminated bottle? The flakes have been double-bagged in my workshop which I keep between 40%-45% RH and when I measured it out, the flakes were a tiny bit stuck together but still crispy and came free with just a little squeeze of the bag. Seemed the same as always as I ground them up.

Is there a shelf life for unused shellac flakes? Should I get new stock? Please share your experience.

Thanks, Chris.
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Re: Old shellac flakes a problem?

Postby Alan Carruth » Wed Sep 12, 2018 12:30 pm

Yes, shellac has a shelf life. As you get it it's somewhat cross linked, which gives it greater toughness than plain resins. Over time, and, I believe, with moisture exposure, it cross links more, and becomes less soluble. I've gotten shellac that would not dissolve at all. The stuff that does dissolve is still useful, so far as I can figure out.

You should try the 'teabag' method of dissolving it. Don't bother grinding it first. Wrap up the shellac you want to use in a piece of old T-shirt material, and suspend the bag in a jar with the alcohol, so that the bag is just touching the top of the liquid. The shellac dissolves out and settles to the bottom, pushing the alcohol to the top. The circulation does the stirring for you. This works especially well with seedlac, which has lots of dirt and wax in it. If you don't squeeze the bag the wax all stays in it, and saves you the trouble of decanting to get rid of it later. This doesn't work as well with more processed shellacs; the wax particles seem to be smaller.
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Re: Old shellac flakes a problem?

Postby Bryan Bear » Wed Sep 12, 2018 5:19 pm

I was going to tell you to try what Alan already said (because I learned it from him). I have some old blonde flakes that are dissolving less and less each time I mix some. Using his teabag method, I don't really have to worry about the stuff that doesn't dissolve. The stuff that does dissolve still seems to work just fine. I'm noticing that over time I have to add more and more shellac to the bag to end up with enough in the mixture.

The only real downside of this is that you can't really know what pound cut you end up with. For me, I never worry about that since I am mixing shellac and alcohol on the pad by feel. If the mixture is stronger I use less shellac, it it is weaker I use less alcohol on the pad.
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Re: Old shellac flakes a problem?

Postby Rick Milliken » Thu Sep 13, 2018 10:24 pm

I’ll further muddy the shellac. I had a similar problem not long ago with methyl from the same source.

I’ve been using Everclear, but ran out, so just used some methyl for a small batch. The difference for me is that in my case the shellac was fresh, open no more than a week or two. I’ve no proof, but seemed to me to be a weak batch of recochem product.

I got some more Everclear and it worked much better
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Re: Old shellac flakes a problem?

Postby Steve Sawyer » Thu Sep 13, 2018 11:15 pm

Can I ask about the use of methyl hydrate? I've never been a heavy user of shellac, but would like to try a french polish some day. I also have a stash of both blond and garnet shellac flakes, so I was following this discussion with interest.

My understanding has always been that the best solvent for shellac is ethanol, as close to pure as you can get, hence preference for products like Everclear. I've also understood that methanol (methyl hydrate) is the denaturant added to ethanol to make it non-potable, thus making common denatured alcohol less than ideal as a shellac solvent.
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Re: Old shellac flakes a problem?

Postby Chris Lounsbury » Fri Sep 14, 2018 9:56 am

Methyl Hydrate is methanol and I use it not by preference but due to availability issues for ethanol. I live in Ontario, Canada under different alcohol regulations than my American friends.
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Re: Old shellac flakes a problem?

Postby Alan Carruth » Fri Sep 14, 2018 12:03 pm

Recently I've been using denatured ethyl alcohol that I found at the drug store, sold as Ethyl Rubbing Alcohol, 70% by volume' under the generic 'GoodSense' brand. The inactive ingredients are listed as: acetone, denatonium benzoate, methyl isobutyl ketone, and water.

All ethyl alcohol contains at least 5% water once you open the bottle. I've been using acetone in my FP for several years, so that's not an issue. The other stuff is probably in very small amounts, and serves to make it extremely bitter, as I found the first time I touched my mouth with my hand after using it. This stuff works well as a FP solvent; there is not enough water to cause any problems. It's also a whole lot cheaper than Everclear, which is getting harder and harder to buy. I trust it more than isopropyl or methyl. Acetone is actually relatively benign, despite the way it smells. It's a by product of normal fat metabolism, and you have enzymes to deal with it, in small amounts. I normally wear a protective glove when French polishing anyway, and you want to use good ventilation in any case.
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Re: Old shellac flakes a problem?

Postby Mark Fogleman » Fri Sep 14, 2018 2:26 pm

Another twist I discovered is that Everclear now has a lower proof (ie higher water content) version on the shelves so read the label. I'm not a regular store visitor and my PJ drinking days are long ago so this may be old news. The original version thankfully is still available by special order in my state (NC).
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