Shellac flakes slow to dissolve

[Patrick Hanna]

Hello, Friends,

I'm aware that dissolved, liquid shellac has a shelf life, so I never use it on instruments after it's more than about four months old. My question is about the shelf life of dry, undissolved shellac flakes. My stash of flakes has been stored, tightly closed, in its original plastic can for about five years. Yesterday I mixed a fresh batch of liquid stuff--the first new batch since February. I did this in a new, clean jar. It seemed to take longer to dissolve than previously. Further, after a while I got distracted and forgot to shake it every fifteen minutes. As you would expect, I had a fairly thick lump in the bottom of my jar as a result. But I was able to easily stir it up with a bamboo skewer and resume shaking. Today I discovered some remnants of partially dissolved flakes swirling in the bottom of my jar. Ergo, a couple of questions:
1. Do you think this is simply the result of my break in the shaking routine?
2. Do dry flakes lose their ability to dissolve after a certain age?
3. I always strain liquid shellac through a coffee filter before spraying or painting it. If I strain this batch, as usual, should I feel confident about using it?
4. Should I start over with a fresh batch, or perhaps buy fresh flakes before starting over?

I'll specify that I like to shoot a few thin sealer coats over the outside of my instruments, then scuff sand, and then begin applying my finish. In this case, the planned finish is Stew Mac rattle can lacquer, and the instrument is a flat top mandolin.

Many thanks for any information you can provide.
Patrick

[Shawn Hoover]

I just had a batch from old flakes (at least five years old, probably not stored as well as yours) that wouldn't completely dissolve at all. Some of it did, but there was a gelatinous glob on the bottom, too. I read in woodworking books not to use it if that happens. Sounds like yours might be turning that way. I did strain it and keep it. I'm going to test a pool of it on glass and see how it dries compared to a really fresh batch.

[Mario Proulx]

Kept dry, the flakes should have a near limitless shelf life. How fresh is your alcohol? Alcohol -will- take-on moisture every time the bottle is opened, and as such the ABV is reduced. Is the room cool, or warm?

I've sped-up the dissolving by crushing the flakes to a finer degree(some folks run 'em through a coffee grinder, even!) and quite often by warming the jar in my glue pot.

[Chuck Tweedy]

Flakes do go bad - and 5 years is about their life.
When old, the symptom is exactly as you described - gel flakes at the bottom of the jar that won't dissolve.

[Patrick Hanna]

Mario:
I dissolved this batch in alcohol that is perhaps six months old. About 1/4 or less of the can used to this point. Flakes and alcohol are stored in my shop (lower level, but air conditioned in summer, so not terribly humid. Considerably drier in winter when the boilers are fired up.) I didn't grind my flakes, but I always do break them up so that no piece is bigger than about .5 inch wide. Most are smaller.

Chuck:
Before I even posted this inquiry, I expected someone would tell me that the flakes can go bad. Well... not your fault. Mario gets nearly limitless shelf life with dry flakes. Yours go bad in time. Looks like mine might have gone bad, too. Maybe it's a long term storage issue because my shop humidity will swing through about 30% from driest to wettest. Let's say about 70% in the wettest months (no glue ups then) and about 40% in the dead of winter. Temp is fairly stable down there.

Regardless, what do you guys think I should do? My shop is what it is. I would have no fear of straining the current batch and using it to seal MDF or whatever. But I'm not so sure about instruments.

I'll probably just start over with new flakes and new alcohol for now. But I sure would like to know what is going on here, and whether the filtered liquid could be used on an instrument. I mean, let's face it, fellas: There's a bunch of otherwise nice liquid shellac in that jar, just mixed yesterday. And filtering out the undissolved stuff with a coffee filter would be a matter of only about three minutes' work. Hate to waste it, but I do realize that would be far better than having a finish issue later on the mandolin.

Have any of you guys tried filtering a batch that didn't show full dissolution? Did it cause problems?

Thanks again,
Patrick

[Dave Stewart]

I'm still using flakes, both blonde & orange, that have got to be 20+ years old....never had a failure to dissolve. Always kept in a basement cupboard. FWIW
Maybe an alc. problem.

[Mario Proulx]

For this batch, I'd suggest filtering it and doing a test with it; it will either dry nicely, or not. My money's on it being fine...

I also suspect your alcohol could be fresher. It will work(after you filter the batch) but isn't optimum.

[Chuck Tweedy]

I don't know how you preserve shellac for so long (Dave & Mario), but even when I keep them in a sealed metal container they go bad over time.
My next-door-neighbor is Vijay Velgi of www.shellacfinishes.com, and he keeps his stock for only 2 years for exactly this reason. He and I even did a un-scientific study where we collected flakes of various age that we both had, and dissolved them. The older and lighter colored flakes showed the "jell-o" problem worst. And it was at about 5 years that most flakes will start to not dissolve well.

I don't know anything about the dissolved shellac from those old flakes - but I purged my stock and only use flakes that are less than 2 years old now. A finish that crazes is far worse than a few bucks for new flakes.

[David King]

Someone gave me a jar of "Luna" flakes a few years and those wouldn't dissolve right from the get-go. I used the jell as a grain filler and that seemed to work albeit with the usual shrinkage. I tossed the lot after someone explained to me that they had gone bad.

[Dave Stewart]

Well, I've only ever bought shellac from Lee Valley, & kept them in the container they came in (bagged for orange and "metamucil" type containers for the Behlens Superblonde.) Production dates on the Superblonde are '94 & '97. The blonde definitely dissolves more slowly as Chuck says.... seldom more than a jello lump in the first day, but fully liquified after the second.
BTW, I've always dissolved to a 5-6lb cut as taught.... just covering the flakes with alcohol. You could double the alcohol (to have its cutting power stay stronger) to end up with nearer 3lb. if you want.

[Bob Gramann]

I get jello with flakes as their age approaches 4 years. I store the flakes in doubled zip lock bags in the freezer. I use Everclear at 190 proof. When I get a jello batch, alcohol out of the same bottle dissolves fresher flakes just fine. I just have a hard time using up a pound of flakes before they are too old.

[Daryl Kosinski]

I use a magnetic stirrer. I let it run for a couple of hours, everything gets dissolved never have had a sludge issue. It is like this one http://www.amazon.com/Hanna-Instruments ... s_indust_1
only I found mine in the trash, The heating unit in it was burnt out but I didn't need that anyway.

[Mario Proulx]

I honestly have some raw flakes from the mid 90's, still! I keep them in a plastic bag, rolled-up, not sealed. My dissolved blond shellac also lasts over a year, typically, though the darker, less refined shellac begins to have that telltale "sweet" smell that tells me to toss it at about the one year mark. Perhaps my use of methyl alcohol instead of denatured helps here, also.

There must be an environmental issue at play with some regions "killing" the dry flakes sooner. Same reason I've made a note of the celluloid on vintage instruments surviving much, much better in my area than the ones I see from the US. Smog? High humidity? Air conditioned homes/workshops?

[David King]

My theory is that something is causing the raw flakes to polymerize. I'm betting moisture plays a roll. That said I've worked on some very old french polished furniture that the finish melted readily on application of fresh alcohol so there's a mystery in there.

[Chuck Tweedy]

So, obviously, I need to store my shellac flakes in Canada. Maybe being continuously bathed in ethanol vapors does the trick.

Seriously, could be moisture, could be temperature, could be the methyl alcohol as well.

[Bob Menzel]

As I'm on the verge of ordering my first batch of flake, this is a timely thread. Would silica gel desiccant help the shelf life?

[Alan Carruth]

I have not had a problem with shelf life of shellac that I've gotten in a long time. I did get some dry shellac about thirty years ago that would not dissolve, but since then I've been getting it from better sources, I guess.

The best method I know of mixing shellac is the 'tea bag'. Put your shellac flakes on a piece of cloth, such as T-shirt material, and tie it up into a bag with some wire. Suspend the bag near the top of a tall jar by bending the wire over the rim, and fill it with alcohol to part way up the bag. The dissolved shellac will fall to the bottom of the jar, pushing the less dense solvent to the top where it can dissolve some more. The resulting circulation does the stirring for you, and you never get a lump at the bottom. Anything that won't dissolve stays in the bag. This is particularly nice if you're using seedlac: the wax particles are too big to get out of the bag (so long as you don't squeeze it) and stat there, along with the dirt, bark, and bug parts. You end up with filtered de-waxed shellac in one swell foop.

[Patrick Hanna]

Wow! You people are the best. Just the sort of speculation and discussion I hoped to receive. Thank you for giving me lots of food for thought. I live in central Missouri, USA, so the humidity does get freakishly high here at times. However, even in the worst summers, my shop never gets above about 60+%--never as high as 65. This is because the shop is in one of my air conditioner zones. In the absolute most bitter winters with the boilers running full time, it will get a bit below 40% in the shop. So, humidity swings might be the culprit. I don't strive to keep the shop at 45% year round. I just quit building when the humidity gets too high. Tomorrow I will buy some fresh alcohol and try another mix. In fact, I REALLY like Alan's tea bag suggestion, so I might try that in a separate jar. I will also try the "thin film on glass" drying test to see what happens. This could take a while, as I am preparing for a one week vacation. But stay tuned. I will report back. Many thanks to all.

[Patrick Hanna]

Hey, Guys, I just had an afterthought:
My alcohol was a fairly new can (maybe three months old) and it's still about 3/4 full, but I DID use it for some metal cleaning in my garage earlier this summer. Thus, there is the possibility of moisture creeping in. Further, it was denatured alcohol, because...well...that's what the label on the shellac flakes specify as a solvent. What do you guys think of using a fresh bottle of rubbing alcohol for my new batch, instead?

Thanks to all,
Patrick

[Bob Gramann]

The rubbing alcohol is either 70% isopropol or 70% ethyl alcohol. That's way too much water for good shellac. Pure ethyl alcohol will quickly go to 95% when it has a chance to suck water out of the atmosphere. That's why Everclear is 190 proof and why it makes no sense to buy anhydrous alcohol for shellac--it will be 95% instead of 100% very quickly. I use Everclear or a competing brand of 190 proof grain alcohol from the liquor store. It doesn't have the objectionable odor of the denatured stuff and I don't worry about being poisoned by the denaturant. 95% works fine for me.