Originally Posted by
cyccommute
Methanol is highly toxic and easily absorbed through the skin. Used by someone who has no knowledge of what it is or how dangerous it is, it could cause a great deal of harm especially if they don't take proper precautions.
So, no, it's not FINE to use. It may work but you should be knowledgable about what you are using and how to use it as with any solvent.
Highly toxic? I think that this needs a more complete description. Methanol is definitely toxic if you drink it an amount of it. But methanol is present naturally in the blood at levels ranging from 1.7 to 3.4 mg/liter (which is the about the same as parts per million). The body processes methanol to produce formaldehyde, which is processed to produced formic acid (formate). Formaldehyde and formic acid are also present normally in the body. The body and tissue are not damaged by methanol or byproducts at normal levels, and the body can clear (process) these compounds at normal physiological levels. The problem is when you ingest or absorb more methanol than the body can process, and you get build-up of formaldehyde and formate. This messes up the blood chemistry severely and this causes blindness and death. You want to limit your body's uptake of methanol is below the point where formaldehyde and formic acid processing is overwhelmed.
Methanol can be produced in making up moonshine and this is the cause of blindness from moonshine. BTW, My grandfather was a baker in the Navy, and his shipmates always were trying to steal bread to filter the bathtub gin they produced on board. Not sure how well that worked removing methanol, but I remember him telling me about it. Anyway, I wouldn't intentionally ingest any methanol, but one source specified a half milliliter as safe for ingestion. As little as 10 ml (two teaspoons, or about a third of an ounce) can give you significant trouble (eye damage or blindness), whereas 30 ml to 100ml (rougly 1 to 4 ounces) can prove fatal. So don't drink any quantity of methanol.
Absorption through the skin is another issue. It takes a heck of a dermal exposure to absorb the equivalent of an oral 10ml dose. The source below had folks stick one hand in pure methanol for up to 16 minutes. That source is flawed (it should have reported any adverse effects, but only stated that some subjects hands were white and dried after the test). But still, the rise in blood methanol after 16 minutes of the entire hand being immersed were still below levels considered toxic (for the record, the max avg methanol concentration ranged from 8.1 - 16.5 mg/dl and the total amount absorbed was estimated by various methods as between 166 and 1506 milligrams. This is about 0.15 to 1.5 ml of pure methanol. The upshot is that this extreme exposure did not give rise to toxic levels.
That said, I'd agree that I'd wear gloves if I was cleaning bike parts with it. But again, I'd prefer isopropanol or ethanol-based rubbing alcohol. The larger molecules might be better solvents for hydraulic fluid. And even methylated spirits (ethanol with a squirt of toxic methanol added so you can't drink it) has a lower concentration of methanol than pure methanol, and you'd absorb less methanol. And again, my opinion is that propanol or ethanol would work better.
*Time-resolved cutaneous absorption and permeation rates of methanol in human volunteers.
Batterman-SA; Franzblau-A, Int Arch Occup Environ Health 1997 Nov; 70(5):341-351