From: William Levak (wlevak_at_grex.cyberspace.org)
Date: 2005-06-22 20:18:46
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. Message was sent through the cbm-hackers mailing list
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