Author: mschmidt
Date: 2009-01-04 00:39
OK--time for the PhD chemist to step in and clear the air.
In the above discussion, there seem to be varying assumptions of what "rubbing alcohol" is; in the U.S.A. it is most commonly isopropanol, but ethanol may also be used, and ethanol is the alcohol in mouthwash. As Dutchy correctly stated, pH is only meaningful in aqueous solution, and both isopropanol (pKa=17.1) and ethanol (pKa=15.9) are too weakly acidic to affect aqueous pH, as anything with a pH greater than 14 won't acidify water. (For those who care, this means it is not an Arrhenius acid. It is, however, a Bronsted-Lowry acid, and can donate H+ to sufficiently strong bases, but that is irrelevant to reeds, saliva and the like.)
(If you add ethanol to distilled water, however, the pH will not be 7, because distilled water in contact with air has dissolved CO2, which is a weak acid, so the pH is likely to be below 6. It is, however, poorly buffered at this pH, and exposure to hard tap water or saliva (pH 7.4 in healthy individuals) is likely to counteract any acidic tendencies.)
But a liquid doesn't have to be an acid to cause damage. In fact, carbohydrates such as cellulose are probably more susceptible to hydrolysis by bases than damage by acids. So whether or not "rubbing alcohol" is an acid is probably not even relevant!
Alcohols are far more likely to cause damage because they are more hydrophobic solvents than water--more likely to dissolve "oily" sorts of things, as vboboe pointed out. And you don't have to steep them for hours--you can feel the "drying" in your skin when you rub alcohol on it for less than a minute, as it very quickly dissolves away the natural "oils" (sebum) in your skin.
BUT--this doesn't mean that reeds are necessarily damaged by alcohols. It all depends on what sort of oily substances are in cane, and whether these are in a position to be dissolved away by a brief dip in alcohol. Vegetable cells have cell walls of cellulose, and oily substances within the cells may not be effectively dissolved by the alcohol.
Mike
Still an Amateur, but not really middle-aged anymore
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