A shellac question


so, if I mix up a batch of garnet shellac and have some left over, can I keep the remainder good by freezing it?
I know that the alcohol will stay fluid.
shellac is an animal material. I assume that lower temperatures will prolong it's shelf life, but will the moisture in the freezer offset the temperature gains?
anybody tried this?
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snipped-for-privacy@all.costs wrote in

just allow the shellac to dry back out in a suitable container and re-use it at a later date? Or is there more than a simple solvent carrier relationship involved?
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There's some esterification (sp?) going on, too. Such that, after a period of time (& other variables), it will fail to cure/harden.
Jeff Jewitt's site, www.homesteadfinishing.com, has some expert info. Much more expert than what I have to offer.
Patriarch
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(snippity-doo-dah....)

reaction (which is mechanical rather than chemical in nature). Estherification is the reaction of an acid with an alcohol (examples - acetylsalicylic acid - asprin - is acetyl alcohol and salicylic acid. Methysalicycalate - oil of wintergreen - uses methyl alcohol instead.) Further in the article on shellac, the author mentions that shellac is not resistant to alkaline products like lye and ammonia due to the acidic nature of shellac. One interesting thing to note is his mention of how different alcohols affect the drying time!
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Precisely why it's used an enteric coating on pills. Safe in the stomach.
No look at almost all your household cleaning products and see what they contain before you consider shellac for your next project.
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Interesting idea. I doubt it would work if you just let the alcohol evaporate by leaving the lid off. It would take too long and give a chance for the alcohol to esterify the shellac acids, especially as the shellac became more concentrated. If you could rapidly remove the alcohol by placing the solution under a vacuum or perhaps by blowing a dry inert gas over or through it, there is a chance it would work but I bet too much alcohol would become occluded in the shellac as it precipitated and you would be back to having a really high concentration of shellac dissolved in the occluded alcohol. While cooling will slow down the esterification, and it being so easy to make fresh, you may as well not do anything special and just test the shellac solution before you go and use it again.
Good Luck.

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snipped-for-privacy@all.costs wrote in

How much did you mix?
Storing the flake in the freezer is an acceptable storage tactic, according to the ancient lore. Since I seldom mix more than about 12 oz at a time, I've never considered the freezer. Works out to maybe $4 worth of leftover at most, in my case.
But then, the Bay Area's climate isn't as severe as Arizona's.
Patriarch
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On Thu, 14 Jul 2005 19:01:37 -0700, snipped-for-privacy@all.costs wrote:

Just keep it liquid, cool and keep using it. The problems of shellac's short shelf life are much over-emphasised.
If it's not bleached blonde or dyed, and it's dewaxed (just by decanting it yourself, if needed) then it'll keep fine. Have some always on hand and you'll find yourself using it for all sorts of small jobs.
What are we talking about anyway ? under a pint ?
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On Fri, 15 Jul 2005 21:37:45 +0100, Andy Dingley

yep, small amount. what I'm trying to avoid is the lead time of allowing the flake to dissolve for a day or so as much as anything. it's handy stuff to have a little around.
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snipped-for-privacy@all.costs wrote in <snip>

The last time I bought shellac, I got the liquid kind from Jeff Jewitt. 5 lb cut in a plastic quart bottle. Really pretty close to the same price as buying flake, plus the solvent.
It's really convenient. And it's the sort of high quality stuff we've come to expect from Jeff.
Ready to go in as long as it takes me to thin it to the cut I want to use. I keep a plastic squirt bottle on the finishing shelf with maybe 6 ounces in it all of the time, because Andy's right. If it's there, it gets used.
Patriarch
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Couple of years ago lots of shellac discussion seemed centered about quick mixing schemes. Put jug with flakes and alcohol in warm water bath and walla. Several talked about measuring flakes then using coffee grinder on the flakes then mixing almost instantaneous brew. I pour flakes in jar half way then fill with alcohol and swirl the brew frequently during the day and USUALLY find it done the same day.
On Fri, 15 Jul 2005 14:39:55 -0700, snipped-for-privacy@all.costs wrote:

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There is very LITTLE moisture in a freezer. Moisture levels in a freezer are MUCH lower than the moisture outside the freezer.
That's what's so great about freezers, they turn water vapor and liquid water into FROST/ICE which drives water vapor out of the air. The colder the air the less water vapor. As long as you don't open and close your freezer excessively, and the lid to your shellac container is closed, there will not be moisture problems. Problems can arise during the THAWING of your shellac if the room it is thawing in is excessively humid. You may have experienced the ugly side of this with a very cold beer on a coffee table with no coaster :)
The concentration of water vapor is TEMPERATURE dependant.
ps = 610.78 *exp( T / (T + 238.3 ) *17.2694 )
ps = vapor pressure. T is temperature in Celsius.

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Please do not confuse this absolute humidity reference with what affects wood -relative humidity.
Chemical reactions are slowed by cooling. Presumably the esterfication of the shellac would be slowed. With a tight cap, moisture is just a red herring.
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Who is confused?
He (the OP) is aware of the benefits of temperature as he stated. He is concerned with the increased moisture in his freezer effecting his shellac. For some unknown reason he thinks he has a higher moisture level in his freezer than outside his freezer. Which defies the laws of physics and is impossible.

Why do you need to presume? Last time I checked, esterification is a chemical reaction.
FYI, For every drop in 10 degrees C, the reaction rate is halfed (roughly).
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I live in Arizona. most of the time, it's waaaay drier in the shop than it is in my fridge.
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OK. Are you putting your shellac in a 'fridge' (refrigerator) or a 'freezer' like you posted originally?
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so far, neither. once I'm done with this project, I'll probably double bag it and store it in the freezer, as dry flakes. the original question was whether freezer storage would prolong the life of _mixed_ shellac, but I got no hard data about that....
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However they also make the air colder, which increases the relative humidity for the same absolute water content. Air inside a fridge or freezer is usually around 100% RH. Anything over this condenses out on the walls. A fridge is less cold than a freezer, but will also have more "new" water entering, on fresh vegetables etc.
For most purposes, i.e. the "activity" of the available water in the air, it's the _relative_ humidity that's important. Fridges and freezers are effectively very damp storage conditions - one reason why they can have such trouble with mould.
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The absolute humidity is MUCH higher outside the freezer than inside the freezer.

You are complicating the issue by bringing up a refrigerator. The OP was concerned with his freezer having more moisture than outside his freezer.

Wrong. For the purposes of this discussion it is the absolute humidity that is important.
Absolute humidity outside freezer: high Absolute humidity inside freezer: low
wrote:

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