I remember reading once that shellac shouldn't sit on the shelf for more than 3 months. In Bob Flexner's book "Understanding Wood Finishing", he says that the moment shellac flakes are mixed with alcohol, the shellac starts losing its ability to cure hard. Who knows how old the cans of shellac in the hardware store are? Odds are they've been there longer than three months already!
For several years now, I've been using shellac flakes that I mix with alcohol. When I do, I write the date on the jar so I know how old it is. My typical batch is about 1.5-2 cups of mixed shellac.
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| My most recent batch - August of 2022 |
The two-step stool that I completed recently got a few coats of this shellac. But before I started, I tested the shellac on a piece of scrap. Over the course of an hour, I gave the stick a few coats and let it sit overnight.
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| The test stick |
Even after a half hour or so, the surface felt perfectly dry - not gummy at all. Certainly after an overnight cure it felt fine. This batch of shellac was mixed 7 months ago. Now, I'm not going to put any other type of finish on top of the shellac, so I don't need to worry that the shellac will interfere with adhesion of a topcoat.
I should mention that my storage conditions are favorable for a longer life. I store the mixed shellac in a cabinet in the shop where it gets very little light and probably has relatively small temperature fluctuations. It's in a mason jar that seals very well.
Does anybody have hard data or empirical knowledge here? Please comment about your experience with using shellac that has aged a bit.
Two year old mixed shellac stored in a Mason jar worked fine for me on a recent project. It behaved as if I just mixed it. It was mixed with 190 proof Graves grain alcohol. It was stored at about 72 degrees and no direct sunlight.
ReplyDeleteCouple of years - wow! That's good to know.
DeleteYes I did test it first to be sure it was ok to use.
DeleteDitto, a couple years life for mine, stored in glass. Just do a test before using to ensure it dries properly. Jim B
ReplyDeleteThanks - now I feel much better about using this stuff after 6-8 months.
DeleteI have read somewhere that shellac can be used for up to 18months. I have only used ubeaut sanding sealer up to that long until it was getting too expensive to buy. I normally try to use all my shellac within 6 months. I too store them inside a cabinet and the flakes inside a bag that keeps them cool and in the cabinet away from sunlight, the same applies to the DAA. The shellac I buy are all stored inside a cool room or fridge.
ReplyDeleteIf the flakes are old, they never fully dissolve and therefore never cure properly. You can do the finger nail test by pressing lightly on the shellac. If it leaves an indentation then the batch is old and needs to be thrown away. I love shellac and I dislike using any other type of finish. I get the look I want and that's all that matters to me. I've also switched to using a foam brush for application over the gramercy shellac brush and the hake brush. For a truly brush free surface you cannot go wrong with a foam brush.
I've been using the same hake brush for several years now. I love how the shellac will harden in the brush when not used, but all it takes is a few minutes soaking in alcohol for it to become like new again.
DeleteAs a personal preference I always cleaned my brushes afterwards. I guess the main reason is that I use different coloured shellac for different projects. Deep down I know it doesn't matter, but out of habit I do it anyway. But since I made that short for YT on how to make a foam brush, I've been using that insstead.
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