Isopropyl Alcohol 100% or Denatured Alcohol for Shellac?

[section1]

My question is inspired from a recent article from Lost art press on mixing shellac. Chris Schwarz in short uses Everclear to dissolve the shellac flakes as opposed to denatured alcohol for reason being that everclear dissolves the flakes completely while the latter doesn't. For those who don't know Everclear is grain alcohol that can be bought in a liquor in the US.
Considering I've had dissolving issues in the past until recently and I'll get to that in a second, I was very excited about Everclear. Everclear isn't sold in Australia but Isopropyl 100% not the other 70% stuff is and is a good substitute for Everclear or grain alcohol as I was told by a fellow Aussie.

Some say that Isopropyl isn't that great for shellac due to it not evaporating as quickly as denatured alcohol. Is this true? This statement totally derives from the yanks and they all make mention of the Isopropyl that's contains 70% isopropyl and 30%water, which in my books shouldn't be used at all. I am wondering though is the 100% or 98.99% Isopropyl just as good as Denatured Alcohol?

Just to clarify why I've had dissolving issues. The shellac flakes I tried to dissolve previously was several years old, since I bought a fresh batch and a magnetic stirrer, they dissolved completely within two hours.

[ian]

My question is inspired from a recent article from Lost art press on mixing shellac. Chris Schwarz in short uses Everclear to dissolve the shellac flakes as opposed to denatured alcohol for reason being that everclear dissolves the flakes completely while the latter doesn't. For those who don't know Everclear is grain alcohol that can be bought in a liquor in the US.

Considering I've had dissolving issues in the past until recently and I'll get to that in a second, I was very excited about Everclear. Everclear isn't sold in Australia but Isopropyl 100% not the other 70% stuff is and is a good substitute for Everclear or grain alcohol as I was told by a fellow Aussie.

Some say that Isopropyl isn't that great for shellac due to it not evaporating as quickly as denatured alcohol. Is this true? This statement totally derives from the yanks and they all make mention of the Isopropyl that's contains 70% isopropyl and 30%water, which in my books shouldn't be used at all. I am wondering though is the 100% or 98.99% Isopropyl just as good as Denatured Alcohol?

Just to clarify why I've had dissolving issues. The shellac flakes I tried to dissolve previously was several years old, since I bought a fresh batch and a magnetic stirrer, they dissolved completely within two hours.
This is what I know ...

100% ethanol (aka grain alcohol) is drinkable. In Australia ethanol is almost always retailed as "metho" and is denatured with either a bittering agent to make it taste worst than "horrible" to discourage alcoholics from drinking it.

"Metho" is an abbreviation for methanol -- it is not ethanol (although ethanol plus a bittering agent is mostly sold as "metho"). I'm not entirely sure how methanol is produced, but importantly methanol is poisonous which is why it is mixed with a bittering agent to make it taste horrible. Drinking methanol tends to send people blind.

Isopropynol is also not ethanol. Commercially it is primarily produced by combining water and propene in a hydration, or by hydrigenerating acetone.
Isopropynol is not drinkable. That is unless you are a really desperate alcoholic.


I've always used Bunnings' sourced "metho" to dissolve shellac flakes. Note that the "metho" I got from Bunnings was really ethanol -- which if I understand your question correctly is the "same" as the Everclear available in the US.


Just remember that commercial "metho" can contain up to 50% water.
Dissolving shellac flakes in fluid containing more than about 5% water is problematic.

[Bushmiller]

Section1

You probably cannot do much better than refer to the Ubeaut website in the Shellac area. My understanding is that if possible you should use IMS, which is 100% Ethanol, and stands for Industrial Methylated Spirits.

This was in the hard shellac section.

HARD SHELLAC - New improved formula finish. (http://www.ubeaut.com.au/hardshell.htm)

Regards
Paul

[Mobyturns]

Just remember that commercial "metho" can contain up to 50% water.
Dissolving shellac flakes in fluid containing more than about 5% water is problematic.

Bunnings supplied Diggers "Metho" contains 5% demineralized water according to the MSDS. "METHYLATED SPIRITS - Other Names Ethanol, Ethyl Alcohol, IMS"

Diggers also produced a "Stove Fuel" which was nearer to 100% Ethanol, but I can no longer find it listed on their site.

[Chesand]

Specialist paint shops should also have 100% Methylated Spirits. Sceneys is another brand.

[BobL]

"Metho" is an abbreviation for methanol -- it is not ethanol (although ethanol plus a bittering agent is mostly sold as "metho"). I'm not entirely sure how methanol is produced, but importantly methanol is poisonous which is why it is mixed with a bittering agent to make it taste horrible. Drinking methanol tends to send people blind.


Virtually all product sold today as Meths is Ethanol.

Extracted from Wikipedia.
True methanol is used mainly in industry and as a racing vehicle (eg drag racers and monster trucks) fuel. Methanol fires have an advantage in that they can be put out with water but a major disadvantage that it burns invisibly.
Drinking 10mL can send you blind and 60-100mL is enough to kill.
Meths was in the past made from coal or heating wood, these days it's produced synthetically using meths or by combining CO2 and Hydrogen, or Biosyntheically using bugs.
Meths can be produced cheaply (c/litre) compared to $/L for ethanol and there have been attempts to use it as a major component in vehicle fuel. Whatever is used it still produces CO2 The EU allows a max 3% meths in vehicle fuel

[derekcohen]

I have always mixed shellac flake or Ubeaut Hard Shellac liquid with Bunnings “meths”. Never had a negative issue.

https://i.postimg.cc/DwsP1D9b/28a.jpg

Regards from Perth

Derek

[ian]

Diggers also produced a "Stove Fuel" which was nearer to 100% Ethanol, but I can no longer find it listed on their site.I thought Diggers "stove fuel" was actually "white spirit" which is Naphtha.
Though with recent changes in Australia to product sourcing, there is some confusion as to whether "white spirit" is the same as mineral turps (which is sold as "white spirits" in the US) or naphtha (Australian practice) or a benzine based paint thinner.

[Lappa]

I believe it’s Shellite, same as Colemans Stove Fuel.

[ian]

I believe it’s Shellite, same as Colemans Stove Fuel.
In Australia, Shellite and naphtha are one and the same.

From the Diggers MSDS
Chemical Entity -- Solvent naphtha (petroleum), light aliphatic -- approximately 100%
other components (should this be "possible contaminants"?) -- n-Hexane -- less than 30%
stated benzene percentage < 0.1%

[malb]

99.x% Isopropyl is available from electronics stores like Jaycar and Radio Parts, it used to be used for cleaning tape heads etc but is also used for cleaning printed circuit boards and such. Evaporation is quite fast for mist applications as per electronics, but I have no comparative information about evap rates relative to other alcohols, and haven't tried mixing shellac using it.

My understanding is that most alcohols will absorb moisture from their surrounds and effectively dilute themselves unless they remain completely sealed in their container, i.e open the container to decant a small amount and recap the container and you are no longer completely sure of concentration.

[section1]

Thanks guys for all your input, you really are very much informed. I went out on a limb and bought Isopropyl 100% and would you believe it the whopping 20L drum because I could find nowhere local anything smaller. Sounds like throwing money down the tube but believe me this is my final spend and knowledge never came cheaply. To cut a lengthy story short, Isopropyl is great for beginners who want to apply shellac with a brush. It does not dry instantly as denatured alcohol even though it may appear dry on the surface but smear your finger or even a rag over the brushed surface you’ll see that’s still very much wet. How long does it take to fully dry? I don’t know because I went to bed disappointed. Isopropyl dissolves the flakes just as quickly as denatured alcohol, but nothing will dissolve outdated shellac.

Derek said that he’s always mixed flakes with metho from Bunnings, which we all know contains a certain percentage of water. I’ve heard this before from an old timer who used to work as a finisher back in his day, and I dismissed it as rubbish. Now, I hear it again and I wonder if I’m the one who has been fed all these years of rubbish. I would like to know why using metho with water in it works with no adverse affect since there is so much emphasis on using IMS100?

[ian]

To cut a lengthy story short, Isopropyl is great for beginners who want to apply shellac with a brush. It does not dry instantly as denatured alcohol even though it may appear dry on the surface but smear your finger or even a rag over the brushed surface you’ll see that’s still very much wet. How long does it take to fully dry? I don’t know because I went to bed disappointed. Isopropyl dissolves the flakes just as quickly as denatured alcohol, but nothing will dissolve outdated shellac.
Ethanol has a molecular weight of 46, so, while not "flashing off" like acetone, will evaporate faster than isopropanol (molecular weight about 60). Under some conditions, water will evaporate faster than isopropanol.


Derek said that he’s always mixed flakes with metho from Bunnings, which we all know contains a certain percentage of water. I’ve heard this before from an old timer who used to work as a finisher back in his day, and I dismissed it as rubbish. Now, I hear it again and I wonder if I’m the one who has been fed all these years of rubbish. I would like to know why using metho with water in it works with no adverse affect since there is so much emphasis on using IMS100?there's three different alcohol involved here.

Methanol is methanol. It is very poisonous. It is still available commercially, but it is not the "metho" sold by Bunnings, et al.

Ethanol is sold by retailers who don't hold a liquor licence (e.g. Bunnings) in denatured form. It's "denatured" with a bittering agent and may, depending on the supplier, contain up to 50% water.
The ethanol sold by Bunnings, et al, is commonly known as "metho" or "meths" and according to the MSDS "methylated spirits" as supplied through Bunnings by Diggers is >= 95% ethanol, water is <= 5%.
Note that Ethanol is also available at 100% concentration for use when making fortified wine.

Isopropanol -- evaporates slower than ethanol and on occasion slower than water. It will work to dissolve shellac, but I wouldn't recommend it.

[Lappa]

In Australia, Shellite and naphtha are one and the same.

White spirits and Shellite are two different things but both use naphtha as their base. Coleman state their stove Fuel is Shellite. White spirits is not used due to some of its constituents. It’s mainly used as a dry cleaning fluid and turpentine substitute.


477824
As you can see, Diggers sell both

when I go to the shop I look for the label on the bottle. It says Shellite. It is still naphtha but it’s easier to call it by it’s common name that people see rather than having to peer at the ingredients.

[Ironwood]

I just finished reading a thread over on the IAP forum along similar lines to this one.
one bloke from the US said that he buys Everclear from a food store and costs $20 a litre compared to a couple of dollars for denatured alcohol. He said it is high strength clear ethanol.

[section1]

I just finished reading a thread over on the IAP forum along similar lines to this one.
one bloke from the US said that he buys Everclear from a food store and costs $20 a litre compared to a couple of dollars for denatured alcohol. He said it is high strength clear ethanol.

$20 a litre is expensive just to dissolve shellac and I really don't know how it's viable for Chris to keep using it since he goes through quite a bit of it.
I had to try the Isopropyl otherwise it would have bugged me indefinitely. I will say one thing though, buying the magnetic stirrer on Chris's advice was the best advice. It really does help with dissolving the flakes quickly and completely whether you crush them or not because I have experimented using both methods. A two hour dissolve time is better than a 24hr without the stirrer and with particular matter still left undissolved.

[jack620]

I also use Diggers metho to dissolve flakes. No issues.

[Ironwood]

$20 a litre is expensive just to dissolve shellac and I really don't know how it's viable for Chris to keep using it since he goes through quite a bit of it.
I had to try the Isopropyl otherwise it would have bugged me indefinitely. I will say one thing though, buying the magnetic stirrer on Chris's advice was the best advice. It really does help with dissolving the flakes quickly and completely whether you crush them or not because I have experimented using both methods. A two hour dissolve time is better than a 24hr without the stirrer and with particular matter still left undissolved.
I just went back and read that thread, he said it was $20 a quart and was drinkable.

The thread was started as a concern about using hand sanitizer with methanol in it, if you would like to read it, post #14 has the bit about the Everclear.
Denatured alcohol | The International Association of Penturners (https://www.penturners.org/threads/denatured-alcohol.166236/)

[jack620]

If you really want 100% ethanol it’s available for under 5 bucks a litre if you buy 20L:

Industrial Methylated Spirits (IMS 100) – EnviroChem Online (https://envirochemonline.com.au/products/industrial-methylated-spirits-ims-100?variant=11026135220266)

$6.60/L if you buy 5L.

[justonething]

Some say that Isopropyl isn't that great for shellac due to it not evaporating as quickly as denatured alcohol. Is this true? This statement totally derives from the yanks and they all make mention of the Isopropyl that's contains 70% isopropyl and 30%water, which in my books shouldn't be used at all. I am wondering though is the 100% or 98.99% Isopropyl just as good as Denatured Alcohol?


Some preparation of rubbing alcohol is 70% isopropyl and 30% water, but rubbing alcohol shouldn't be used. We can buy 99% isopropyl here quite easily. I would agree with you that isopropyl would dissolve shellac more readily than ethanol because of the extra Hydrocarbon chain in its molecular constitution. One can always further dilute the dissolved shellac with 95%+ ethanol, which would allow it to dry more readily.

The reason all ethanol will gravitate towards 95% once opened is that ethanol is hygroscopic until it is 95% proof.

Methanol is not a suitable solvent really, for the opposite reason that isopropyl is. It's best to leave it as a fuel in the racing industry.... It makes your car go fast.

[ian]

I just went back and read that thread, he said it was $20 a quart and was drinkable.

The thread was started as a concern about using hand sanitizer with methanol in it, if you would like to read it, post #14 has the bit about the Everclear.
Denatured alcohol | The International Association of Penturners (https://www.penturners.org/threads/denatured-alcohol.166236/)
Hi Brad

'cause we're discussing chemicals it would pay to be a bit more precise with what posters on foreign forums say

Nebraska is one of the 36 states where you can still buy both,
95% Ethanol poisoned with Methanol,
Denatured in the home improvement store for about $5/quart and
95% Ethanol drinkable, Everclear in the grocery store for $20/quart (my punctuation)
now why any sane person would deliberately "poison" ethanol with methanol is beyond me, but we are talking about post-prohibition era Yanks.

Denatured alcohol from the home improvement store will most likely be 95% ethanol plus 5% ethyl acetate to "render the mixture unsuitable for drinking".
Everclear, presumably a brand name, contains 95% ethanol plus water, and as stated is drinkable. Although at $20 per quart, why wouldn't you buy the home center's $6 per quart denatured stuff?

In the EU, ethanol is "denatured" in accordance with the following formula
"Per hectolitre (100 L) of absolute ethanol: add 3 litres of isopropyl alcohol, 3 litres of methyl ethyl ketone and 1 gram denatonium benzoate (https://en.wikipedia.org/wiki/Denatonium_benzoate)."
(denatonium benzoate is a really effective bittering agent, with dilutions as low as 10 ppm being unbearably bitter to most humans.)


BTW
the volume of a US quart is about 946 ml -- i.e. about 1.5 US fluid ounces less than a litre.

[Mobyturns]

I thought Diggers "stove fuel" was actually "white spirit" which is Naphtha.
Though with recent changes in Australia to product sourcing, there is some confusion as to whether "white spirit" is the same as mineral turps (which is sold as "white spirits" in the US) or naphtha (Australian practice) or a benzine based paint thinner.

I have taken a photo of the bottle for the non-believers "Diggers Bio-Flame" & found a copy of the MSDS.

Please note Diggers no longer list it on their website. Why? Now that's a good question as the MSDS for their Metho and Bio-Flame ingredients are identical. Yet the product container for Bio-Flame states "Contains: min 99% ethanol." MSDS are unreliable for "exact" %'s as they state a range & do not list some "proprietary" chemicals.

Chemical Entity CAS Number Proportion (%)
Ethanol 64-17-5 >= 95
Demin. Water 7732-18-5 <= 5

[Mobyturns]

If you really want 100% ethanol it’s available for under 5 bucks a litre if you buy 20L:

Industrial Methylated Spirits (IMS 100) – EnviroChem Online (https://envirochemonline.com.au/products/industrial-methylated-spirits-ims-100?variant=11026135220266)

$6.60/L if you buy 5L.

Funny how we all think! Woodturners want 100% IMS yet the cleaners want economy "Is soluble in water and hence can be extended with water to provide economy in cleaning tasks." So why don't the cleaners just use "Metho?"

[RossM]

...The reason all ethanol will gravitate towards 95% once opened is that ethanol is hygroscopic until it is 95% proof...
Just to clarify - 95% alcohol by volume (ABV) would be 190 proof, or 95 proof would be 47.5% alcohol by volume. (Using the seppo definition of proof).

The term "proof" came from a 16th century test for purity of alcoholic spirits for taxation purposes. If the spirit would burn, it was deemed to be above proof and taxed at a higher rate. Some tests also used the ability of gunpowder soaked in the spirit to burn as the "proof". These tests defined 100 proof; being about 57% ABV.

The seppos later defined 100 proof as being 50% ABV

[justonething]

If you really want 100% ethanol it’s available for under 5 bucks a litre if you buy 20L:

Industrial Methylated Spirits (IMS 100) – EnviroChem Online (https://envirochemonline.com.au/products/industrial-methylated-spirits-ims-100?variant=11026135220266)

$6.60/L if you buy 5L.

If you click on the link. The picture says its 95% Ethanol Solution. Same as Diggers Methylated spirit.

[RossM]

99% Ethanol at $4/litre:

Ethanol 5 Litre | Denatured Alcohol | Sydney Solvents (https://www.sydneysolvents.com.au/ethanol-5-litre)

[jack620]

The picture says its 95% Ethanol Solution.

So it does. I’ll give them the benefit of the doubt and assume they’ve used the wrong photo, as they also sell IMS95. I’ll check though.

[jack620]

99% Ethanol at $4/litre

$8 per litre by my calculations.

[Slave]

Metholated spirit can leave an oily type of residue on glass which can be quite difficult to remove

[Lappa]

Are you sure it’s metho?
We used metho to do a final clean on brake hydraulic components because it DOES NOT leave a film.

[ian]

Are you sure it’s metho?
We used metho to do a final clean on brake hydraulic components because it DOES NOT leave a film.
ah, the confusion between
pure methanol -- CH3-OH
methyolated spirits -- CH3-CH2-OH , plus up to 50% water and an additive to make the mixture non-drinkable
and drinkable ethanol -- CH3−CH2−OH (a.k.a. grain spirit)
continues


so which type of "metho" are Lappa and Slave refering to ??


BTW
methanol (single carbon atom, plus an -OH), ethanol (two carbon atoms, plus an -OH), propanol (three carbon atoms, plus an -OH) are all miscible in water.
Miscible means 100% soluble.
Butanol (four carbon atoms, plus an -OH) is the first of the alcohols considered non-miscible.

[BobL]

There's a good reason most meths is typically 95% (by meths I do mean ethanol :))

Again from Wikipedia

Fractional distillation (https://en.wikipedia.org/wiki/Fractional_distillation) at atmospheric pressure can concentrate ethanol to 95.6% by weight (89.5 mole%). This mixture is an azeotrope (https://en.wikipedia.org/wiki/Azeotrope) with a boiling point of 78.1 °C (172.6 °F), and cannot be further purified by distillation.

Addition of an entraining agent, such as benzene (https://en.wikipedia.org/wiki/Benzene), cyclohexane (https://en.wikipedia.org/wiki/Cyclohexane), or heptane (https://en.wikipedia.org/wiki/Heptane), allows a new ternary azeotrope comprising the ethanol, water, and the entraining agent to be formed. This lower-boiling ternary azeotrope is removed preferentially, leading to water-free ethanol.At pressures less than atmospheric pressure, the composition of the ethanol-water azeotrope shifts to more ethanol-rich mixtures, and at pressures less than 70 torr (https://en.wikipedia.org/wiki/Torr)(9.333 kPa), there is no azeotrope, and it is possible to distill absolute ethanol from an ethanol-water mixture. While vacuum distillation of ethanol is not presently economical, pressure-swing distillation is a topic of current research. In this technique, a reduced-pressure distillation first yields an ethanol-water mixture of more than 95.6% ethanol. Then, fractional distillation of this mixture at atmospheric pressure distills off the 95.6% azeotrope, leaving anhydrous ethanol at the bottom

In other words to produce more than 95.6% Meths costs $$

IPA is even worse as purifying IPA by simple distillation only leads to 88% IPA.

You can always make your own real methanol by heating wood chips in a sealed container and condensing the output vapour - it will contain a heap of water (and other crap) so will need secondary distillation. Because Methanol has a significantly lower boiling than ethanol it can be better separated from water,
WATCH OUT for fires. :D

[Mobyturns]

Bob, so when a manufacturer says their product contains "Min 99% Ethanol" they are probably telling a Furphy! :rolleyes:

[Lappa]

ah, the confusion between
pure methanol -- CH3-OH
methyolated spirits -- CH3-CH2-OH , plus up to 50% water and an additive to make the mixture non-drinkable
and drinkable ethanol -- CH3−CH2−OH (a.k.a. grain spirit)
continues


so which type of "metho" are Lappa and Slave refering to ??


BTW
methanol (single carbon atom, plus an -OH), ethanol (two carbon atoms, plus an -OH), propanol (three carbon atoms, plus an -OH) are all miscible in water.
Miscible means 100% soluble.
Butanol (four carbon atoms, plus an -OH) is the first of the alcohols considered non-miscible.

No confusion in my mind.
I’m talking about the common, everyday “metho” that you buy at Bunnies, Coles, Woolworths, Hardware stores labelled as Methylated Spirits.

477973

BTW - never heard of Methyolated Spirits - must be a Canadian thing :rolleyes:
Also, which of the above would leave an oily film on glass?

[ian]

never heard of Methyolated Spirits - must be a Canadian thing :rolleyes: I don't believe that I ever claimed to be able to spel :rolleyes:





which of the above would leave an oily film on glass?I really don't know, but suspect that once the ethanol percentage drops below 100 proof (i.e. the water content exceeds 50%) the water might lead to observed streaking (I'm not sure that I've correctly spelled "streaking")
BobL may have a better handle on the issue.

[jack620]

Bob, so when a manufacturer says their product contains "Min 99% Ethanol" they are probably telling a Furphy! :rolleyes:

Unlikely. They'd be opening themselves up for prosecution.

I rang the supplier in the link I posted above. They have used the wrong photo. He confirmed his IMS-100 is 100% ethanol.

So, if anyone wants 100% ethanol at a reasonable price it is available in Melbourne and Sydney from the links above. If you want to make your own poisonous methanol from wood, well you could do that too I guess.

[Lappa]

Just noted an interesting spec. on the picture I posted.

I normally buy Coles Brand Methylated Spirits which states >95% ethanol. Due to a run on Methylated Spirits (by people making their own hand sanitiser), Coles have had no stock for months.
It only came back in to my local store about 3 weeks ago and now it’s Glendale brand which I see states <95% ethanol.
Thank goodness for this thread as I was just about to make a new batch of shellac and I never use Metho with less than 95% ethanol and the Coles brand has always been successful. BTW, I always open a brand new bottle when dissolving the flakes or buttons and use the remainder for cleanup etc.

[BobL]

Bob, so when a manufacturer says their product contains "Min 99% Ethanol" they are probably telling a Furphy! :rolleyes:

No - it probably just means they have paid to have it purified.
Like bottled water the cost of the ethanol in a bottle of ethanol is the minor component.
Ethanol costs very little to make - it's the packaging, storage, distribution and marketing/advertising that costs.


But claiming 100% purity for anything is a complete crock.
That's one thing I heavily trained in and practiced at work ie the the nominal level of impurities in any material..

And don't forget that water is not the only contaminant.
The highest purity lab grade ethanol I have seen from a specialist lab supplier was >99.8% pure and that was about $200/L
At work we further purified this by a process know as evaporative distillation - not to get the water out (in fact this process added water as we didn't care about the water) but to reduce the trace metal contaminants which were in the sub microgram per gram range. we used to lose about half the ethanol in the process

We also used to produce some of the cleanest lead free water on earth.
Starting with tap water, sediment and charcoal filters, reverse osmosis, double deionisation, triple sub boiling distillation.
At this point the lead concentration was around 10 femtograms per gram.
That's 6 orders of magnitude less that micrograms per gram (micro, nano, pico, femto)
Yet we did not claim 100%

[BobL]

I don't believe that I ever claimed to be able to spel :rolleyes:
I really don't know, but suspect that once the ethanol percentage drops below 100 proof (i.e. the water content exceeds 50%) the water might lead to observed streaking (I'm not sure that I've correctly spelled "streaking")
BobL may have a better handle on the issue.

Not sure- there are lots of other organic materials in unpurified ethanol which are also likely to produce the streaks.

[RossM]

No - it probably just means they have paid to have it purified.
Like bottled water the cost of the ethanol in a bottle of ethanol is the minor component.
Ethanol costs very little to make - it's the packaging, storage, distribution and marketing/advertising that costs.


But claiming 100% purity for anything is a complete crock.
That's one thing I heavily trained in and practiced at work ie the the nominal level of impurities in any material..

And don't forget that water is not the only contaminant.
The highest purity lab grade ethanol I have seen from a specialist lab supplier was >99.8% pure and that was about $200/L
At work we further purified this by a process know as evaporative distillation - not to get the water out (in fact this process added water as we didn't care about the water) but to reduce the trace metal contaminants which were in the sub microgram per gram range. we used to lose about half the ethanol in the process

We also used to produce some of the cleanest lead free water on earth.
Starting with tap water, sediment and charcoal filters, reverse osmosis, double deionisation, triple sub boiling distillation.
At this point the lead concentration was around 10 femtograms per gram.
That's 6 orders of magnitude less that micrograms per gram (micro, nano, pico, femto)
Yet we did not claim 100%
I suspect they can get away with saying that because it would be considered +/- 1% (Well - minus really :), given the claim) The number of significant digits in the claimed measurement impacts precision of the claim.
They probably won't get away with 100.0%

[RossM]

Methanol should not be considered for use with shellac. It causes the shellac to become very brittle and crazed.

The confusion some have is the term "methylated spirits". Be confused no more. "Spirits" is an old term for highly distilled grain alcohol, in other words ethanol. The longer term is "rectified spirits". The process of "methylating" it involved adding a small quantity methyl alcohol to poison it so it would not be consumed. The authorities wanted to ensure anyone consuming alcohol paid taxes, and the seppos did not want anyone to drink alcohol. Another term is denatured alcohol. These days we add bittering agents, rather than adding methanol to poison it, and sometimes an agent to induce vomiting.

You can substitute 2-propynol for ethanol when mixing shellac. It will marginally affect drying time, but otherwise works well.

[BobL]

I suspect they can get away with saying that because it would be considered +/- 1% (Well - minus really :), given the claim) The number of significant digits in the claimed measurement impacts precision of the claim.
They probably won't get away with 100.0%

Technically speaking, to claim the default +/- 1% they would need to state it as "100. %"
Implied +/- 1 only applies to rightmost non-zero digit on the left hand side of a number with no decimal point.
Technically 100 (no decimal point) is considered as +/-100.
So 110 implies +/-10, 101 +/-1
This does not apply to digits on the RHS of a decimal point, ie 100.0 does imply +/- 0.1

This is about as nerdy as this gets because nobody actually writes 100. +/-1
We had a few debates about such minutiae on that International Science panel I served on for a couple of decades.

[Chesand]

"Spirits" is an old term for highly distilled grain alcohol, in other words ethanol. The longer term is "rectified spirits".

When some Latin terms were still used in pharmacy it was known as SVR - Spirit Vini Rect - Rectified Spirit of Wine. Showing my age now.

[RossM]

Technically speaking, to claim the default +/- 1% they would need to state it as "100. %"
Implied +/- 1 only applies to rightmost non-zero digit on the left hand side of a number with no decimal point.
Technically 100 (no decimal point) is considered as +/-100.
So 110 implies +/-10, 101 +/-1
This does not apply to digits on the RHS of a decimal point, ie 100.0 does imply +/- 0.1

This is about as nerdy as this gets because nobody actually writes 100. +/-1
We had a few debates about such minutiae on that International Science panel I served on for a couple of decades.
Now getting off topic, but - the treatment of trailing zeros in whole numbers varies and does not always follow the convention noted above, and is a real can of worms. For complete disambiguation where it matters, these numbers should really be written in scientific notation, where the number of significant digits is completely defined. Eg 1 x 10 to power 2 vs 1.00 x 10 to power 2 (the first being 100 with one significant digit and the second having three significant digits.)

However for the 100% ethanol above, there is wiggle room for the claim made; much more so if you interpret the number as having only one significant digit.