Ethanol Versus Methanol

I purchased a container some years ago of what I think is high grade (?) clear methylated spirits to mix some shellac. Problem is the label has fallen off and even though I wrote on the container "methylated spirits" I'm unsure if it's ethanol or perhaps methanol. I carried out a burn test this evening and got a blue flame mixed with yellow. I've read mixed comments online, some state ethanol burns blue others state methanol burns blue.

Besides carrying out something like an iodoform test is there any "easy" way to distinguish the two (besides inhaling)?

Thanks.

The difference between the densities is tiny but is easily measures using a hygrometer.
Someone you know may have one.

If you can't find one they are dead easy to make - just look them up on the web.

The density of Methanol is 786.5 g/L while ethanol is 785.1, so the hygrometer will float slightly higher in Methanol than in ethanol.

Another way is to completely fill a small plastic bag with the liquid and place it in ethanol - if it sinks the liquid is methanol.
To be sure you should do the reverse - and it should all be consistent

You should be able to work it out from there.

Bob, I think with a few year old sample, and both being hygroscopic the density difference wont help to distinguish them.

Agree with Ben, also the original concentration is not likely to have been 100% unless it is laboratory grade.
I have a litre of duty paid 100% ethanol which will make a few decent liqueurs, no way am I putting shellac in it.........
Mark

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Originally Posted by benhoskin

Bob, I think with a few year old sample, and both being hygroscopic the density difference wont help to distinguish them.

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If the bottle has been near full and tightly closed it won't have picked up much water.
If it has, a hygrometer will pick that up pretty quickly i.e. density will be above 786.6 g/L.

If the liquid floats in fresh pure methanol it will still be a definitive test that it is ethanol.
If it sinks in ethanol it could be methanol (with or without water) or ethanol with or without water.
A small amount could always be redistilled :- an then tested.

Disclaimer - I am not an industrial chemist, although I am a scientist.

My understanding is that, at least here in Australia, all reasonably priced commercially available (e.g. hardware store) ethanol has a proportion of methanol added to it so it is unsafe to drink (send the drinker blind for one). That protects the alcohol industry and the tax man as they make their living & collect taxes on drinkable alcohol respectively. So, unless you especially purchased pure ethanol (very expensive) or pure methanol (from an industrial chemical supply - and why would you?) then it is most likely that you have "metho", i.e. ethanol with methanol added.

Some brands of metho can contain a fair bit of water and those are useless for shellac - the finish turns white and chalky.

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Originally Posted by Xanthorrhoeas

Disclaimer - I am not an industrial chemist, although I am a scientist.

... it is most likely that you have "metho", i.e. ethanol with methanol added.

Some brands of metho can contain a fair bit of water and those are useless for shellac - the finish turns white and chalky.

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Correct. What you get commercially is either Meths which is Ethanol with Methanol in it (to save on having to pay liquor excise and be subject to alcoholic beverage restrictions) or Iso-Propyl Alcohol. Ethanol is what is in drink and IPA is used for cleaning (I keep a spray bottle for my electronics work).

In any case it should be perfectly fine for shellac since Ethyl/Methyl/Propyl alcohol have very similar chemical properties and all should be fine for shellac. It is merely a medium for dissolving the shellac and evaporating leaving the shellac film behind and all three will do that. There is no actual chemical reaction taking place, just solution and evaporation.

The only caveat is if the water content is too high and you will soon see that. But if it was not properly sealed then it would have evaporated.

John

John

Quote:

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Originally Posted by Xanthorrhoeas

Disclaimer - I am not an industrial chemist, although I am a scientist.

My understanding is that, at least here in Australia, all reasonably priced commercially available (e.g. hardware store) ethanol has a proportion of methanol added to it so it is unsafe to drink (send the drinker blind for one). That protects the alcohol industry and the tax man as they make their living & collect taxes on drinkable alcohol respectively. So, unless you especially purchased pure ethanol (very expensive) or pure methanol (from an industrial chemical supply - and why would you?) then it is most likely that you have "metho", i.e. ethanol with methanol added.

Some brands of metho can contain a fair bit of water and those are useless for shellac - the finish turns white and chalky.

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I haven't looked at all the MSDS but I will use Diggers Brands as an examples MSDS Information | MSDS Information | Recochem - Australia because it constitutes a high volume product

Diggers
Ethanol 95 contains 95% ethanol,
Ethanol 100 Contains at least 99% ethanol,
Meths contains >99% ethanol, If there was methanol in it it would have to state it.
Ethanol CT95 contains >95% ethanol.

Adding methnol was a tactic along with Strychnine uses in the US during prohibition
It's illegal to put methanol in ethanol because making people blind constitutes GBH and is punishable by law but traces of other compounds are added to make people sick (vomit) but they are not permanently harmed.

Quote:

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Originally Posted by BobL

I haven't looked at all the MSDS but I will use Diggers Brands as an examples MSDS Information | MSDS Information | Recochem - Australia because it constitutes a high volume product

Diggers
Ethanol 95 contains 95% ethanol,
Ethanol 100 Contains at least 99% ethanol,
Meths contains >99% ethanol, If there was methanol in it it would have to state it.
Ethanol CT95 contains >95% ethanol.

Adding methnol was a tactic along with Strychnine uses in the US during prohibition
It's illegal to put methanol in ethanol because making people blind constitutes GBH and is punishable by law but traces of other compounds are added to make people sick (vomit) but they are not permanently harmed.

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Interesting. The Methylated part was due to adding Methyl Alcohol (methanol) so that has changed. Hence why they call it de-natured in the US as opposed to meths. Depending on the brand they can de-nature it (make it unpalatable) with any number of compounds including methanol, but in the case of Diggers they add about 1% bittering agent to it which is not in the MSDS sheet.

In any case more or less irrelevant since it should still be perfectly fine for shellac.

John

I thought methanol burns invisible? Thats why you occasionally see a Indy car pit crew worker jumping around as if he is on fire....because he is on fire but the bystanders can't see it. Though the flames kind of show up on TV if you look closely.

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Originally Posted by GarethR

I purchased a container some years ago of what I think is high grade (?) clear methylated spirits to mix some shellac. Problem is the label has fallen off and even though I wrote on the container "methylated spirits" I'm unsure if it's ethanol or perhaps methanol. I carried out a burn test this evening and got a blue flame mixed with yellow. I've read mixed comments online, some state ethanol burns blue others state methanol burns blue.

Besides carrying out something like an iodoform test is there any "easy" way to distinguish the two (besides inhaling)?

Thanks.

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if you're using it to dissolve shellac flakes or as a solvent, as Xanthorrhoeas said it doesn't matter.

If you're proposing to use it for some other purpose, like fortifying or increasing teh alcohol content of home made wine, then I'm not sure any of us should be helping. :rolleyes:



as a bye-the-bye
some years ago there was a fatal explosion and fire at one of the Hunter Valley wineries involving a large tank of ethanol.
What I found intriguing was that no one, including the coroner, ever publicly asked or commented on what a winery was doing storing large quantities of ethanol. I, and I'm sure most others, have been lead to believe that the alcohol in wine and beer is the product of fermentation of the grapes, barley or wheat, and not a bulk industrial chemical added at the end of the process.

Thanks guys.

Realise either would be fine to dissolve shellac flakes, my concern was if it's methanol I'd rather not deal with it due to the toxicity.

Might just get rid of it responsibly and purchase some ethanol.

A little while back I made my first forays into using shellac. I took advice from the most expert person I knew: Ubeaut.

He explained to me that the supermarket methos contain vast amounts of water. He was right.Around about half. He explained that to achieve good results with shellac I needed IMS which is Industrial grade Methylated spirits. If I couldn't get that the Diggers brand at 95% purity was passable but not ideal.

I did have some trouble sourcing the pure stuff but finally did find Toowoomba Woodworks could supply it.

I think it would be easier to find suppliers in the major cities. I know this is a slight digression from the distinction between methanol and ethanol, but it does identify that with such a small difference between the two in density, differentiation may be difficult particularly outside of laboratory conditions.

Regards
Paul

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Originally Posted by ian

as a bye-the-bye
some years ago there was a fatal explosion and fire at one of the Hunter Valley wineries involving a large tank of ethanol.
What I found intriguing was that no one, including the coroner, ever publicly asked or commented on what a winery was doing storing large quantities of ethanol. I, and I'm sure most others, have been lead to believe that the alcohol in wine and beer is the product of fermentation of the grapes, barley or wheat, and not a bulk industrial chemical added at the end of the process.

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They probably knew that Drayton's made fortified products........

In Australia it's very unlikely you have purchased " methanol" unless you have specifically saught it out as either racing fuel or a laboratory product.

We have not for a very long time, If ever added methanol to ethanol to make metholated spirit.
It is denatured by adding a bittereing agent.

Methanol is pretty toxic and has very few ligitimately necessary uses.

cheers