How to "thin" shellac?

[sera0516]

I saw in a discussion on afixing cap bands that thinned shellac was recommended, though not as one of the best practices.

 

What do you thin shellac with?

 

Why would you not use it full strength to keep a cap band from sliding around?

[Chthulhu]

I saw in a discussion on afixing cap bands that thinned shellac was recommended, though not as one of the best practices.

 

What do you thin shellac with?

 

Why would you not use it full strength to keep a cap band from sliding around?

 

Thin (and clean up) with ethanol (denatured alcohol). The reason for thinning for this purpose is to help it penetrate the gap between the band and the cap; straight out of the container it's possibly too thick to do this effectively.

[richardandtracy]

In the UK we can't get denatured Ethanol very easily, but the usual solvent for shellac is Methanol (meths), which is what I use.

 

Regards,

 

Richard.

[Canoodler]

 

Thin (and clean up) with ethanol (denatured alcohol). The reason for thinning for this purpose is to help it penetrate the gap between the band and the cap; straight out of the container it's possibly too thick to do this effectively.

Denatured alcohol usually refers to rubbing alcohol--ethanol that has been "denatured" with something to render it undrinkable. Rubbing alcohol normally contains water as a diluent (diluting liquid for those who have forgotten high school chemistry). An easy source of 100% ethanol in the U.S. is liquor stores, where it is taxed as alcoholic beverages. It costs less there than at another source--pharmacies. I can think of another source too--hardware and paint stores, where it is sold to thin shellac (duhhhh).

Edited October 26, 2009 by Ron Z

[Paddler]

Thin (and clean up) with ethanol (denatured alcohol). The reason for thinning for this purpose is to help it penetrate the gap between the band and the cap; straight out of the container it's possibly too thick to do this effectively.

 

Denatured alcohol usually refers to rubbing alcohol--ethanol that has been "denatured" with something to render it undrinkable. Rubbing alcohol normally contains water as a diluent (diluting liquid for those who have forgotten high school chemistry). An easy source of 100% ethanol in the U.S. is liquor stores, where it is taxed as alcoholic beverages. It costs less there than at another source--pharmacies. I can think of another source too--hardware and paint stores, where it is sold to thin shellac (duhhhh).

 

Rubbing alcohol is isopropyl alcohol. It is called "rubbing" alcohol because it has a smooth, almost oily, feel when rubbed on the skin. It is usually sold in drug stores in a concentration of 70% by volume because it is antiseptic at that concentration. "Denatured" alcohol is ethyl alcohol that has had methyl alcohol mixed with it to make it poisonous to drink. You do not drink isopropyl alcohol, either. I don't know whether isopropyl alcohol will thin shellac or not.

 

Paddler

Edited October 26, 2009 by Ron Z

[Chthulhu]

To add to my previous post, my can of Zinsser shellac says that it contains both ethanol and isopropanol, and that cleanup may be done with either ethanol, or household ammonia and water.

[Ron Z]

To add to my previous post, my can of Zinsser shellac says that it contains both ethanol and isopropanol, and that cleanup may be done with either ethanol, or household ammonia and water.

 

But you can not thin shellac with ammonia. That is done only with alcohol, and the alcohol most commonly used in the US is denatured alcohol.

[gregamckinney]

Can denatured alcohol be obtained at the grocery or drug store, or do I need to go to a hardware or paint store?

 

Thanks, greg

[Chthulhu]

But you can not thin shellac with ammonia. That is done only with alcohol, and the alcohol most commonly used in the US is denatured alcohol.

 

Correct.

[Ron Z]

Can denatured alcohol be obtained at the grocery or drug store, or do I need to go to a hardware or paint store?

 

Thanks, greg

 

Hardware or paint store.

[ZeissIkon]

In the UK we can't get denatured Ethanol very easily, but the usual solvent for shellac is Methanol (meths), which is what I use.

 

It's been my understanding that "meths" is in fact denatured alcohol -- "denatured" refers to alcohol that's been rendered unfit to drink; in America this is often done by adding about 1% gasoline (which makes it taste terrible), but in UK it's traditionally been a small percentage of methanol, rendering the stuff poisonous without as many compatibility issues (compared to adding gasoline). That said, pure methanol probably would work as a thinner or solvent for shellac; there aren't many things that are soluble the ethanol that aren't in methanol (though a few things break down in one that don't in the other).

[richardandtracy]

It's been my understanding that "meths" is in fact denatured alcohol -- "denatured" refers to alcohol that's been rendered unfit to drink; in America this is often done by adding about 1% gasoline (which makes it taste terrible), but in UK it's traditionally been a small percentage of methanol, rendering the stuff poisonous without as many compatibility issues (compared to adding gasoline). That said, pure methanol probably would work as a thinner or solvent for shellac; there aren't many things that are soluble the ethanol that aren't in methanol (though a few things break down in one that don't in the other).

Meths, or methanol is the stuff that's available here, not denatured ethanol. The tax people are the ones to put the mockers on the ready availability of denatured ethanol - because it must be taxed as if it's a fine Whiskey (ie I'm guessing, not being a drinker, but it may be up to about £8 tax/litre) and whoever sells it must have a license to sell alchohol. I know what you're thinking; but sanity and taxation need not necessarily co-exist.

 

To prevent people drinking meths, a chemical (usually called 'Bittrex') is added to the meths as well as a purple or magenta dye.

 

Regards,

 

Richard.

[Chris]

Just to clarify the situation here in the UK, 'meths' is NOT methanol (methyl alcohol or wood alcohol) but is short for methylated spirits. Methylated spirits is ethanol (ethyl alcohol) denatured with methanol (to make it extra poisonous) and usually Bitrex (to make it undrinkable) plus a purple dye to make it clearly 'meths'.

 

Other grades of denatured alcohol are obtainable (without purple dye for example) but not readily to the public.

 

You can buy undenatured ethanol, but you will pay a lot for it because of all the excise duty levied.

 

Chris

[PJohnP]

Denatured alcohol is usually what's called an azeotropic mixture (also sometimes called a "constant boiling mixture"), where it's not easily possible to further distill the ethanol (ethyl alcohol). There are methods to "break" azeotropes, but that's not generally possible for the kitchen chemist to undertake. There are several materials that are used to make ethanol "denatured" for this purpose.

 

Generally speaking, if one wants to dilute shellacs in a repeatable and quality-oriented manner, they're well advised to get the denatured ethanol from a hardware store that carries shellacs and finishes for woodworkers, as there can be some issues with quality on the cheapest solvents (and talk with some fine woodworkers about this - one is likely to get an earful on the topic).

 

I generally would not recommend getting rubbing alcohol from a drugstore. It's relatively diluted (70% up to 90% isopropanol with the remainder water), and while it's dandy as a disinfectant, it's probably not what one would ideally want to make up a predictable dilution of a shellac. It might work, but it's not as good for precise dilution as a "pure" denatured ethanol with a controlled low water content.

 

 

 

John P.

[Chthulhu]

Everclear, perhaps? <G>

[Ron Z]

I generally would not recommend getting rubbing alcohol from a drugstore. It's relatively diluted (70% up to 90% isopropanol with the remainder water), and while it's dandy as a disinfectant, it's probably not what one would ideally want to make up a predictable dilution of a shellac. It might work, but it's not as good for precise dilution as a "pure" denatured ethanol with a controlled low water content.

 

True. Wal Mart sells 91% isopropyl alcohol. But you don't want any water in your shellac.

 

Here in the US it's possible to buy 100% isopropyl alcohol for electronics applications. It's used to clean PC boards (removes the rosin flux), tape heads etc. Marketed by GC Electronics. But denatured alcohol is much cheaper, and can be bought by the gallon, which is good if you use as much as I do.

[ZeissIkon]

As pointed out above, paint grade (or even technical grade) denatured alcohol will not be 100% strength, any more than 91% rubbing alcohol is; the azeotrope for ethanol is around 90% (yes, that's the same 180º proof as Everclear, but denatured is cheaper because there's no "beverage" tax on it). "Absolute" alcohol, as the 100% strength is called, is quite expensive because of the difficulty of removing that last few percent of water.

 

For shellac, I'd avoid even 91% isopropyl, however, just because it's a different solvent, not significantly cheaper than denatured (my local grocery/pharmacy sells the 91% isopropyl for $1.89 a quart; I can buy solvent grade denatured for under $3 the quart last I checked -- and a quart is enough to dissolve two pounds of shellac flakes, enough for many thousands of sac jobs), and denatured is well known to work well. Denatured mixes better with gasoline, too, in case you want to dispose of your excess alcohol via your fuel tank (a quart in a full tank shouldn't cause any problems with any modern vehicle).

[Chthulhu]

McMaster-Carr (http://www.mcmaster.com) lists on catalog page 2003:

 

99% Denatured ethyl alcohol at $16.18 per quart

99% Isopropyl alcohol at $16.28 per quart

99% Methanol at $12.91 per quart

 

Other size containers are also available.

[ZeissIkon]

McMaster-Carr (http://www.mcmaster.com) lists on catalog page 2003:

 

99% Denatured ethyl alcohol at $16.18 per quart

99% Isopropyl alcohol at $16.28 per quart

99% Methanol at $12.91 per quart

 

Other size containers are also available.

 

Yep, I call that expensive. And don't forget, after you open the can, you'll have rapidly degrading strength; alcohols that strong will pull water right out of the air, until they reach the azeotrope strength.

[FarmBoy]

Everclear, perhaps? <G>

Azeotrope. About 95% ethanol and 5% water.