Gip, what's the difference in alcohols?

Good question Mike
I was wondering the same thing after seeing both kinds of Alcohol (Ethyl & Iso) in the store.

Mike,
Alcohols belong to a class of organic compounds that contain oxygen.

CH3OH is methanol. It's used in racing fuels, and windshield washer fluids, among other things. It's also called wood alcohol, wood naphtha, and Columbian spirits.
CH3CH2OH is ethanol. It's used in the production of gasohol, is the alcohol found in alcoholic beverages, and is the functional ingredient in waterless hand cleaners--like Purell and other manufacturers make. Ethanol causes bacterial cell walls to break apart (lyse), thereby killing them. It also goes by the name "grain alcohol".
(CH3)2CHOH is 2-propanol-- better known as isopropyl alcohol-- is the stuff you get at the grocery store called "rubbing alcohol". Normally, rubbing alcohol is about 70% isopropyl alcohol in water. Isopropyl is also used industrially as a cleaning agent in concentrations of about 99%, and is also used as the wipes you get before you get a shot at the doctor's office. This stuff is called IPA, isopropyl alcohol, and 2-propanol.

There are other alcohols (butanol, pentanol, etc.), but I'll just stick to the more common.

Because alcohols can interact by hydrogen bonding with water, they are quite soluble in water. As a matter of fact, methanol, ethanol and propanol are soluble in water in all proportions (i.e., infinitely soluble). They also have higher boiling points than their constitutional isomers. For example, ethanol (CH3CH2OH) has a higher boiling point (78 degrees C) than dimethyl ether (CH3OCH3) does (-24 degrees C). Alcohols can also act as very weak acids or bases.

Toxicity is different for each alcohol.
Methanol has an allowable 8-hour exposure of 200 ppm, and a short term exposure limit (15 minutes) of 250 ppm. This material can also be absorbed directly into the bloodstream through intact skin. It affects the central nervous system and can cause neuropathies, vision problems, etc.
Ethanol has an allowable 8-hour exposure of 1000 ppm. Studies have found ethanol to be teratogenic (affects developing fetuses). Maybe you've heard of fetal alcohol syndrome.
Propanol has an allowable 8-hour exposure of 400 ppm, with an allowable short term exposure (15 mins.) of 500 ppm. It cause irritation of the mucous membranes, and like the other alcohols can cause defatting of the skin.

These alcohols are also flammable.
Methanol--flash point = 52 degrees F
Ethanol--flash point = 55 degrees F
Propanol--flash point = 53 degrees F

Any of the alcohols can be used to clean the acrylics from an airbrush, or thin acrylic enamels, although I think IPA is the best choice. I've never heard of ethyl rubbing alcohol, although I see no reason why it shouldn't exist; however, I'm not sure why it would contain acetone.

What else you wanna know?

Hope this helps a little, my friend.
Gip

thank you i just learned something new

QUOTE: Originally posted by styrene Mike, I've never heard of ethyl rubbing alcohol, although I see no reason why it shouldn't exist; however, I'm not sure why it would contain acetone.

Gip,

The bottle says it is ethyl alcohol 70%.
The other inactive ingredients are: acetone, denatonium benzoate, methyl isobutyl ketone, and purified water.

Thanks for that very imformative post also. You are a storehouse of information my friend.

Mike

Rubbing alchohol with acetone is made for the slight warming effect on the skin of the alcohol dilating the peripheral blood vessels as it enlarges the surface capillaries, then the immediate cooling effect of the two substances evaporating VERY quick.. (although different chemical makeup, think Icy Hot)

wonder if it evaporates too quick for the paint to settle right? It would probably be easier to use ISO, the ethanol one would probably require a retarder which defeats the cause...

Gip
Thanks for that very informative explanation it is great to have so many good people here that know what they are talking about

What about denatured alcohol???

Gip,

That is pornography for nerds. I find my self slightly titillated.

I implore you, write up an article on solvents for FSM along with the other info you have posted. This is something we could all use; beginner to advanced.

Another example of the level of expertise found in the boards that I would like to have in print for the archives.

QUOTE: What about denatured alcohol???

Found this explanation at an organic chemistry site. Hope it helps.

In order to reduce the need for strict control and heavy taxation on industrially produced ethanol, the alcohol is denatured. Denaturing is a process of adding other compounds to the ethanol to render it unfit for consumption. Denaturants are selected to give the ethanol a disagreeable taste or odor and in some cases a distinctive color. In some cases the substances added are toxic and produce gastric disturbances upon ingestion and/or other unpleasant symptoms. A large number of different "denaturants" are utilized dependent upon the use for which the ethanol is intended. These denaturants include methyl isobutyl ketone, pyronate, kerosene, acetone, turpentine, amyl alcohol, methyl alcohol, and various butyl alcohols. In some cases more than one denaturant is utilized.

QUOTE: The bottle says it is ethyl alcohol 70%. The other inactive ingredients are: acetone, denatonium benzoate, methyl isobutyl ketone, and purified water.

QUOTE: Rubbing alchohol with acetone is made for the slight warming effect on the skin of the alcohol dilating the peripheral blood vessels as it enlarges the surface capillaries, then the immediate cooling effect of the two substances evaporating VERY quick.. (although different chemical makeup, think Icy Hot)

Based on the definition above, I would tend to believe that acetone and MIBK are used more as a denaturant than to provide any warming characteristics. But that's just my opinion.

Gip Winecoff