Shellac problem

[Rick Lindstrom]

I'm having a strange problem with some shellac I mixed yesterday-

I wanted to make some 1/2# cut to use as a wash coat, so I measured out the ingredients and set it aside to dissolve. The shellac is some super-blonde kushmi powder that I've had stored for a bit over a year in a "cool and dry place" in its original packaging. Last time I used it, it was fine. The alcohol is from a 2/3 full gallon of denatured that I've had for about a year also. Last time I used it, it was fine.

The shellac looked like it was going fine, I agitated it at intervals, etc. etc. Today however, what I have is a container with about half nearly clear fluid, and half sort of congealed or gelled junk in the bottom. It's not solid, but it settles out pretty quickly if I swirl it and set it down.

I've not had extensive experience with shellac, so I don't know what might have caused this. My best guess is that after a year in the garage the alcohol has absorbed enough water from the air to be a problem.

Anyone have an idea what's up with this?

Thanks-

Rick

[Gail Hester]

I use a one pound cut (not for a wash) and dissolve the shellac in ever-clear. Once it mixes it never settles out. Some shellacs come with other things in them such as wax. I avoid these and only use de-waxed shellac. I’m not sure if this helps you since we’re using different products but that’s how I do it.

[Tony Francis]

I have seen that problem before. Just keep stirring/shaking, it will dissolve and probably be fine. But check that it will dry on a scrap before using it on your instrument.

Shellac tends to take longer to dissolve than its less refined cousins, TN or Seedlac.

Best,

Tony

[labraid]

half nearly clear fluid, and half sort of congealed or gelled junk in the bottom

Really? Half and half? 'Coz that sounds like it might be more than a 1/2# cut in essence.

If it's just a thin layer of gel in the bottom though, that's half dissolved shellac that needs more time. Remember you can "double boil" your shellac to get it in service real quick like. It's standard practice in the varnish world, not a shortcut.

[Dave Cohen]

I have found that Hock brand and Behlen's brand super blonde shellacs seem to dissolve much faster when I put the flakes + alcohol on the window sill. Hypothesis is that some photons are involved in the dissolution process. If I were to leave the shellac + alcohol in a dark corner, there would be flakes gradually getting gooey for anywhere from 8 - 24 hrs, but on the window sill, it's mostly dissolved in less than an hour. I've done the double boiler trick, but take it from an old p-chemist, the window sill is a lot safer.

http://www.Cohenmando.com

[David Newton]

Year old alcohol sends up a red flag. Sounds like H2o in the alcolol, shellac doesn't go bad easily.

[PaulD]

Well, we're coming up on 2 days since you mixed the shellac... any change? I'm with the campers above who are guessing it's just taking a little longer to dissolve. I've never worked with a powdered shellac... only buttons and flakes... so I don't know how it behaves. I'm guessing it kinda glued itself into a mass that's taking a little longer to absorb the alcohol. Second guess would be that it's got wax in it and you'll be fine if you let it settle and decant the good stuff into a separate jar.

I've mixed with Everclear and denatured, and mixed with old alcohol and new, and not run into problems. I prefer Everclear for its odor and non-toxicity, but due to its price I usually use denatured. I imagine any alcohol will cause water problems if it's old enough, but out here in the dry desert I've never had it go bad in a year or two.

pd

[Rick Lindstrom]

Well- this is dewaxed shellac and it worked fine a year ago (the first time I used it)- mixed it the same way and it dissolved completely clear in 24 hours or less with no sediment at all. Dried great, looked great, etc.

This time around with the same ingredients, it winds up with a deep layer of sediment that hasn't dissolved after three days.

Just for kicks I bought some fresh alcohol and got the same results. The only conclusion I can come to is that the shellac is bad.

Rick

[David Newton]

I've never heard of dry shellac going bad, but I guess yours did.

I inherited a cardboard box of Belen orange shellac flakes that my dad bought in the late 50's to finish a chest of drawers he built. I mixed some up a few months ago and they were fine. It was waxy shellac and I had to decant it. I wonder if the wax preserves it?

[PaulD]

I've read some things where folks talk about shellac flakes going bad and other folks say that they're good as long as they're stored dry and sealed up. I bought a bunch of shellac in about '97 when a Galoot on the OldTool list was putting together a bulk order. I've got waxed and dewaxed in blond, super blond, orange, lemon... etc and haven't had any problem with any of it. Maybe it stores better in our dry Utah climate than in Florida, or maybe there was something different about the powder you've got from the flakes and buttons I've got. Last winter I finished my daughter's fiddle with some dewaxed blond dissolved in denatured alcohol that was probably a couple years old and it worked perfectly. I did a clear wash coat and several color coats for a sort of cherry/sunset-burst with the same shellac.

If it were mine, I would decant what I had brewed up and test it on some scrap to see if it hardens properly. Since you're using it for a wash coat I would think it wouldn't be too critical as long as it dries clear and adheres properly.

pd

[markishandsome]

Powder would probably absorb water faster than flakes, i think.

[labraid]

If it degrades while dry, I couldn't imagine how bad a situation that'd be on an instrument. Be happy it happened in a plastic bag. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/smile.gif Bummer, in any case.