Shellac. A story and some questions.

[joel]

Who knew that Shellac was such a black art? The internet hasn't been very helpful. Most searches return forums with half truths or conflicting opinion. I’ve got some articles that describe the basic process of making and using it, but there isn’t much fact around when things appear to go wrong.

The Back Story

I've got some old Blonde Dewaxed and some old standard Orange. Both about 8 years old and both been through several interstate moves and not generally looked after very well. The Blonde Dewaxed had set into a block and had to be smashed apart, but the Orange was still nicely flaky. I made two jars of 1lb cut, 6g flakes to 50mL metho. Unsurprisingly (to some of you at least) it doesn't dissolve very well. The Orange turned into a horrible looking mass of glop. After about a week, the Blonde Dewaxed is about half dissolved and half translucent flakes gently floating at the bottom of the jar.

After sifting through a lot of dubious information, I went out a bought some Feast Watson Orange Shellac from Bunnings. Mainly to experiment with and test the lessons I'd learned from the web. I also bought some nice fresh metho, since it absorbs water from the air and mine may have been too adulterated. Well, this stuff dissolved within 20 minutes. Excellent, I thought. Except it has stayed an opaque hazy mixture. Some dusty looking stuff has settled down the bottom of the jar.

So, today I did some experiments with my partially dissolved Blonde Dewaxed and my new hazy Orange (original Orange has been consigned to the bin). Apparently, you can test the "goodness" of shellac by leaving some to dry on a smooth surface. If it's soft, no good. If it's hard and flakes off, it's good. On thin smears, both old Blonde Dewaxed and new Orange flake off when dry. I've got a small puddle of the Blonde Dewaxed drying over night to test in the morning. But the early results look promising.

I also made three swatches of the timber I'm building with from offcuts. King Billy, Alpine Ash, QLD Maple. All sanded to 320 grit. Half of each surface was done with Dewaxed Blonde, half with the hazy Orange. I did three coats all force dried with a heat gun on low. Each looked OK. Each sanded OK too. I sanded with the same 320 grit paper I used to prepare them, and neither type gummed up on the sandpaper, producing a nice fine dry dust. I didn't notice any haziness when the Orange was on the timber. I further tested these swatches with some Minwax Wipe on Poly, to 2 coats. I didn't notice any problems with adhering or drying. But these tests were only over the course of an afternoon.

It's been rather cold and wet down here over the last couple weeks, so I thought I’d treat the hazy Orange to a nice warm bath. I have an old baby bottle warming machine in the shed that fit the bill. The haze appeared to coagulate and begin to slowly flocculate. I looks quite a lot like the cold break you get in freshly boiled beer wort when it cools down prior to pitching the yeast (if any of you practice the fine art of homebrewing you’ll know what I’m talking about).

Aside: I’ve also been experimenting with drying metho as I originally thought that my hazy Orange was due to water in the metho. It turns out Epsom salts (Hydrated Magnesium Sulfate) can be turned into an effective dessicant. The Salts contain an equal weight of water in the normal state (as you buy it from the shops). If you bake off the water in an oven at 200 degrees C for an hour or two it turns into Anhydrous Magnesium Sulfate (MgSO4) which absorbs water, but not alcohol! I now have a jar of absolutely dry metho. I just need to carefully decant it off the MgSO4 before use.

The Questions (Finally)

1. When I gave the hazy Orange a warm bath, did I effectively de-wax it?

2. Why would the solution remain hazy like that until heated? Will it return to being hazy when it cools down?

3. Even though the Blonde Dewaxed only partially dissolves, if it tests OK will it be alright to use on my guitar? I plan to do 2 or 3 Shellac coats followed by thinned Wipe on Poly to build a nice shiny finish. I’m hoping I can just decant off the undissolved flakes and use as normal.

4. Why does flake Shellac turn insoluble? I’ve read that it might be a reaction to oxygen in the air with heat accelerating the reaction. Perhaps Oxygen absorbers will prevent this reaction?

If anyone has any other tips, tricks, or just good plain old-fashioned facts about Shellac that might be useful, please speak up!

[kiwigeo]

Joel we can discuss your queries when you pop around on Tuesday....

[Allen]

Dewaxed white shellac has quite a short shelf life. If it's the stuff that is powered like granulated sugar, it really should disolve over night with nothing left over. Flake shellac would have a longer shelf life but at 8 years not being taken care of, again I'd say it's too old.

I learnt the hard lesson about the shelf life of shellac and it's not hardening up sufficiently several years ago. It passed the tests of drying and sanding, but when enough build was applied I found that the heat of my hand would leave imprints in the surface.

My advice is that getting fresh product is the way to go. Far too much time and effort goes into building an instrument to try and save a bit by using the stuff you have.

[peter.coombe]

Yep, shellac does have a shelf life. The actual length of time it is good depends on how white it is and the temperature and humidity it is stored at. Keep it cool and dry and it will last some years. The clear transparent stuff has the shortest shelf life, it does not last long at all, the dark shellac has the longest shelf life. If it is not completely dissolved in metho overnight, chuck it and get some fresh. Always use the dewaxed stuff.

[blackalex1952]

Where is the best source of dewaxed shellac in Aussieland?- Ross

[kiwigeo]

Where is the best source of dewaxed shellac in Aussieland?- Ross

Liberon make the stuff....I think the last batch I got came from Carbatec here in Adelaide. LMI and Stewmac carry the stuff also. Ive also bought supplies from this crowd in the US https://www.shellac.net/

My recent builds have been finished with hard shellac supplied by Shines here in Australia....he supplies Trevor Gore with his shellac.

[blackalex1952]

Thanks, Martin. The hard shellac sounds like a lot of fun! Ross

[kiwigeo]

Thanks, Martin. The hard shellac sounds like a lot of fun! Ross

From my experience, hard shellac is a slightly different beast than conventional shellac but once you get the hang of applying the stuff it gives a very durable finish. Trevor uses an azeotropic acetone/meths mix when he applies his hard shellac. I use a more conventional french polish method using only meths. I use paraffin oil as a lubricant on the pad having tried other oils with mixed results.

[blackalex1952]

looks quite a lot like the cold break you get in freshly boiled beer wort when it cools down prior to pitching the yeast (if any of you practice the fine art of homebrewing you’ll know what I’m talking about).

Joel we can discuss your queries when you pop around on Tuesday....

Martin! I suggest you pop around to his place for the day and help drink the home brew whilst advising him....-
R

[joel]

looks quite a lot like the cold break you get in freshly boiled beer wort when it cools down prior to pitching the yeast (if any of you practice the fine art of homebrewing you’ll know what I’m talking about).

Joel we can discuss your queries when you pop around on Tuesday....

Martin! I suggest you pop around to his place for the day and help drink the home brew whilst advising him....-
R

Hehehe! Only if you speak fluent gibberish (the international standard language of the inebriated).

And thanks Martin for the workshop tour!

[kiwigeo]

And thanks Martin for the workshop tour!

No worries Joel...was a pleasure to meet you and talk guitar making for a few hours. We'll have to organize another catch up when the weather is a bit better.

[routout]

Yup shelf life flakes had a re think 6 years kills it On another tangent I had some button lac and crunched it up a bit dissolved well no dramas ,that's the extent of my knowledge of short term memory ....