|When we last spoke of shellac our hero had said all my shellac dissolves send me some dewaxed shellac and I will try to dissolve it. We had found that just about everything dissolved if we agitated it enough. Large chunks weren't a problem either - agitate and all was well. even better than lots of old flakes. We found that most people didn't agitate enough.|
Live and learn.
Two challengers picked up the gauntlet and sent us samples. Patrick Edwards send us a bag of 8 or 10 year old platin ( a highly refined blond) and Mark Schofield of Fine Woodworking sent something I think about 3-5 years old.
Mark's stuff sort of dissolved - it needed a lot of agitation but there was residue - ghost flakes that would not go away, I would not call it dissolved. Patrick's stuff just laughed at me. But now we had real samples that did not dissolve.
The problem was figuring out how to get shellac to not dissolve quickly - we didn't need an answer in three years. It took some doing but it turned out destroying shellac is pretty easy to do. Oxygen! if you take some perfectly fresh shellac, put it in a bag, fill the bag with oxygen it will quickly lose it's ability to dissolve.
It's not heat, it's not humidity, it's oxygen.
Waxed shellac has a very very long shelf life because the wax protects the shellac. The coating of wax keeps the shellac from clumping in the heat and it prevents the oxygen from getting to the shellac. Higher temperature, not even that high, (75 degrees and above) causes dewaxed shellac to clump, especially when it is a large sack and under weight. This is annoying but the clump does limit the contact oxygen has with the insides of the clump. The biggest problem comes about when shellac is repacked into regular plastic bags and jars. These containers are all permeable to oxygen so over time - several years the outer layer of shellac flakes oxidizes (or the oxygen speeds up a polymerization process I don't know but the result is the same) and the shellac won't dissolve. For the first several years the oxidation layer is thin so agitation solves the problem - the actual amount of skin that won't dissolve will be minute and unnoticed. But after a few years the entire flake won't dissolve. Chunks as I said, have a longer shelf life.
If you put the shellac in a refrigerator the low temperature will slow down the reaction and refrigerators are also air tight so there is a limited amount of oxygen to for the flakes to oxidize with. The low temperature also keeps the shellac from sticking together which isn't the same as stopping oxidation but people hate breaking up chunks and associate (erroneously) the chunks with aging.
The solution to the problem.
All our shellac, both the Tiger Flakes and BT&C shellac that we sell through Woodcraft, now come in resealable oxygen barrier bags, and include an oxygen absorber. We store all our stock in a refrigerator, and we do not ship shellac wholesale during the summer (and haven't for several years). All the new batches of shellac are labeled so that we can trace back anything bad to which shipment it was. We also test every bulk bag of shellac we import to make sure it dissolves properly when we get it. The photo above is a box of sample dissolve tests from our last packaging run. We are not sure if refrigerator storage is necessary except to prevent clumping as the cold will also slow the oxygen absorption. We are testing that now.
Our goal is mostly to ensure that the shellac that we, Woodcraft, and the Woodcraft stores warehouse will be fine when you buy it. The flakes might be clumped if it got exposed to heat - not everyone refrigerates - but it should dissolve fine. Of course when you get the shellac, you should reseal the bag once it is open, and store the flakes in a cool place.
As far as we know we are the first vendors to pack shellac in a way that will extend its shelf life and while we are continuing our tests we are very optimistic that this will help everyone have fewer problems with their shellac. Incidentally we don't actually have many reports of problems. It's only an issue for shellac that has been sitting for a bunch of years.
A question people do ask is why don't we just sell waxed shellac? For two reasons, one we think the finish you get with dewaxed shellac is cleaner and harder. The second reason is that while most people know to just let the wax settle it's an extra step that beginners may neglect and end up having problems.
In other news:
On the alcohol front: after months on being out of stock we finally have available BT&C 200 Proof Ethanol. This is the best stuff for dissolving shellac that we know of. The problem was that in order to sell denatured alcohol this pure we needed a special permit. We now have it. The only fly in the ointment is that I don't know if when we run out of our current stock if we will be able to get more.
On the shellac front: for the past few years the shellac crop in India has failed. Shellac prices have soared! Since we don't want to warehouse shellac just to protect ourselves against price rises - we actually fly the stuff in for freshness - you will see another price rise, if not by the end of the year, shortly after it.
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