Furniture Finishing, Refinishing, & Restoration
Q&A Forum - Dangers of methanol?
greentree - Mon Mar 31, 2008 3:22 am
Post subject: Dangers of methanol?
Lately, I have been experimenting with shellac as a finish. During the process of dissolving the shellac into the alcohol, by accident, I came into contact with methanol on my hands and I would like to know how much effect this short exposure may have on my health. I wasn't aware of the dangers, but I rubbed methanol onto my hands to remove shellac off my hands. I later read the MSDS sheet on methanol and it indicates it is fairly toxic to breath and to absorb into your skin. Must wash hands for 15 minutes after exposure! And so I am somewhat concerned. - Next time I will use the correct type of alcohol - ethanol.
Does anyone know how dangerous it is to have methanol spill onto your hands? Should we wash our hands for 15 minutes? Both my daughter and I were not wearing gloves for about a minute while we were applying methanol-thinned shellac. Will there be any long-terms effects for her? After an hour of research into the dangers of methanol (after the incident) we washed our hands - but is it too late at this point? (Next time I will surely wear gloves or find a safer alcohol.)
I suppose the trouble all began with a trip to my local wood supplier where a couple of people advised me that any alcohol would work with shellac - and so to go with the least expensive - methanol (it actually reads "methyl hydrate" on the label - its the same thing as methanol). I looked all over my city (New Westminster, BC) for ethanol and couldn't find a source - except for an expensive product custom mixture at Lee Valley Tools. In retrospect, I should have bought this mixture - I think it was mostly ethanol.
Does anyone know of a good source here in western Canada for ethanol for safely dissolving and using shellac?
I read many books about shellac and they must all be american books because they all recommend a product called "denatured alcohol" - but here in Canada I can't seem to find any - or any alcohol to use to safely dissolve shellac.
According to what I have read, there are 4 types of shellac: methanol, ethanol, butanol and propanol. Methanol is toxic, butanol has a strong odor and propanol (the alcohol in rubbing alcohol) has too much water content. This leaves ethanal as the best choice for mixing shellac. But it is difficult to find here in Canada. Any suggestions?
KaiB - Mon Mar 31, 2008 10:31 am
Methyl Hydrate is a synonym for methanol. Denatured alcohol is ethanol which has been rendered "undrinkable" be other agents...mostly methanol.
The limited exposure you have had to the alcohol should not be an issue at all. MeOH is indeed a poison, but at these levels, I personally would not be concerned.
KaiB - Mon Mar 31, 2008 11:02 am
Now that I think of it, "methylated spitits" is denatured alcohol...perhaps this is what it is sold as in your neck of the woods. It should be inexpensive.
greentree - Mon Mar 31, 2008 1:38 pm
Thanks very much Kai for your comment,
That sounds re-assuring.
Next time I will use neoprene gloves and the proper mask (for Volatile Organic Compounds - VOC) when using methanol. Better yet, I will use ethanol instead of methanol. Due to the fact that denatured alcohol still has a small amount of methanol in it, I wonder if isopropyl alcohol is a safer choice as a shellac thinner? I am aware I would sacrifice some performance (isopropanol has a little water in it and isopropanol will dry the shellac slower) but for the sake of your health that might be a good choice. Or am I being too critical of denatured alcohol (mostly ethanol with a little bit of added methanol)? Any thoughts anyone? Basically I am very concerned about the dangers of methanol - even in small amounts as there often is in denatured alcohol.
KaiB - Mon Mar 31, 2008 1:46 pm
While this forum is public internet and I may be wrong, I will say you are a bit over-concerned (I do human health risk assessments for a living...so pay no attention to me).
I for one love the smell of shellac and varnishes-they bring back fond memories. Of couse, I washed my hands in gasoline for years on the farm...don't do it now as it dries them a bit much.
Perhaps others will chime in...
Zeeman - Mon Mar 31, 2008 5:56 pm
Your fears of chemical exposure are valid. You made a mistake in washing with the alcohol, but it was a short term issue. The big risk is continued exposure. When you use any solvent, simply protect your skin and eyes, and wear a respirator if the fumes are present indoors. Using standard denatured alcohol for your shellac thinning is fine. . .
greentree - Thu Apr 03, 2008 7:59 pm
Next time I will avoid methanol (methyl hydrate is the same thing) and use ethanol instead (which is what is mostly in denatured alcohol plus sometimes a very small amount of methanol unfortunately - but its only a small amount) Thanks for these helpful points of view. I'll probably use denatured alcohol and use it outside so as to not breath it in and I will be sure to use gloves as an extra safety measure. Thanks!
I might be overly cautious with this but better too safe than not safe enough.
dave_the_woodworker - Fri Apr 04, 2008 8:30 am
One product that you might consider is a shellac solvent from Wood Finishers Depot (woodfinishersdepot.com). They offer a 200 proof alcohol that has no water or methanol (item LT200-Q). Their description:
"Excellent solvent blended specifically for dissolving shellac. Store-bought denatured alcohol is almost always 190 proof or lower. There can be as much as 7-8% water and 10% Methanol in there with the balance made up of Ethanol. This alcohol contains NO WATER OR METHANOL. This mixture of sub-micro filtered alcohol will evaporate at a slower rate than other denatured alcohols because it does not contain methanol or volatile ketones such as acetone. This alcohol is extremely low odor, making it very suitable for spray applications. A perfect alcohol for all types of shellac reduction."
This is what I use for all my shellac work now. I find that it dissolves shellac flakes faster than regular denatured alcohol or Behlen's BEKHOL. Remember to keep the container tightly closed or it will absorb water from the air (all alcohols have a high affinity for water) and the claim of having NO WATER will no longer be true! It's a bit more expensive, however, at $8.95/quart or $28 for four quarts. But getting rid of the nasty stuff in cheaper alcohols is worth it to me.
Hope this helps,
greentree - Thu May 01, 2008 7:51 pm
This was exactly the kind of product I was looking for - something safer than what I have now. Really appreciated! Good luck with your wood working!