Re: Rubbing Alcohol

From: David Wood (
Date: 2005-06-22 20:54:30

While we're on the topic of rubbing alchohol as a cleaner, I suggest adding a single drop of soap for cleaning things, as the soap will help the alchohol break some things down that it normally couldn't. ;-)


On Wed, 22 Jun 2005, William Levak wrote:

> It has been said here, and other places, that if you buy Isopropyl
> Alcohol, and the label on the bottle says "Rubbing Alcohol", that means
> that it contains 1 per cent mineral oil.
> This is nonsense!
> Being a chemist myself, I can tell you that the terms "rubbing alcohol"
> and "isopropyl alcohol" mean exactly the same thing.  In the off chance
> that pharmacists do things differently, I asked my local pharmacist.  He
> agreed with me.
> I can also tell you that, by law in the United States, ingredients must be
> listed on the label.  If it does not say that it contains mineral oil on
> the label, it does not contain mineral oil.
> ---------------------------------------------------------------------------
> The usual concentration of isopropyl alcohol is 70 per cent in water.
> This makes a good cleaning agent for many things that do not come off in
> water alone.  The drawback is that it will leave water behind when it
> evaporates, not a good idea on circuit boards.  For circuit boards, 90 per
> cent isopropyl alcohol is better.  It will not leave water behind, and
> will actually remove water.  This is because 90 per cent isopropyl alcohol
> is above the azeotrope of 78 per cent. ( I throw in that big word because
> I spent a lot of time and money learning enough chemistry to know what
> that means, and I occasionally like to get some use from it. )
> For things that do not come off in isopropyl alcohol, lighter fluid is a
> good bet.  It is a light petroleum fraction and makes a good non-polar
> solvent, while isopropyl alcohol is a polar solvent.  ( These some are
> more of those chemical terms. )
> -----------------------------------------------------------------------
> OK, chemistry class for today is dismissed.  You can return to what you
> were doing before.
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