Vacuum leak question

[prestonbarrows]

Very good post but I suggest avoiding methanol- that stuff is rather toxic for people and bad for the environment; rubbing alcohol or even high proof alcohol can be used (yes, they have water.) But dust off works as well for me and has the advantage that electrical connections can be sprayed safely.

Yes, this is a good point for the uninitiated.

Methanol is fairly toxic, you should not make a habit of lathering it over your skin. However, it is quite safe with modest procedures centered around wearing gloves and avoiding contact.

Ethanol is much better from a functional/safety standpoint. unfortunately, due to silly laws in the US, pure ethanol is difficult/impossible to come by. The average DIYer will find it impossible. At best, the average citizen will be able to purchase ethanol spiked with methanol to the point that it is poisonous, aka denatured alcohol.

Of course, it is well within the means of anyone technically minded enough to construct a fusor to construct an apparatus which produces laboratory grade pure ethanol. But that is a topic for another corner of the web.

[Dan Knapp]

You can buy 95% (190 proof) ethanol in many liquor stores as "Everclear," although you're paying the tax to be able to drink it. The other 5% is water. The 95% concentration is the highest you can get by simple distillation, because the 95% ethanol/5% water azeotrope boils lower than pure ethanol. The 95% ethanol is fine for cleaning purposes. To get absolute (100%) ethanol, you add some benzene and distill off the benzene-water-ethanol azeotrope to get rid of the water. The remaining ethanol contains traces of benzene, which is why one never should drink absolute ethanol unless you are certain it has been further processed to remove traces of benzene. This is probably more than you wanted to know; but the point was that producing pure ethanol by the amateur is not as simple as it might appear, and that 95% ethanol is readily available (to those of legal age) if you're willing to pay the taxes.

[Richard Hull]

Another way to get to absolute ethanol is to bake some Copper Sulfate crystals in an oven to chase off the water. (they go from a beautiful blue to snow white). Immediately transfer the baked material to a tightly stoppered small bottle of everclear. The copper sulfate will turn blue rapidly. Leave it overnight. Decant the now water reduced everclear to another tighly stoppered small bottle. Rebake the copper sulfate until snow white again and drop it into the new bottle of higher ethanol and if that sees the copper sulfate turn blue or bluish then repeat until the baked copper sulfate remains snow white in the bottom of the bottle of ethanol. The white copper sulfate in the bottom remains as a great indicator of the state of your absolute ethanol into the future. Absolute ethanol sucks water from the atmosphere. It is up to you to keep it absolute by quickly opening and closing the storage bottle and seeing that the copper sulfate remains white over time.

Note: the above is an old microscopist trick and works great. For our purposes, straight everclear would do fine by itself.

I have had to go to Maryland or North Carolina to buy everclear as the ABC stores here stopped handling it after some 3 or 4 darling little collegiate "cup cakes" at UVA killed themselves drinking purple passions some years ago at some frat party. Fortunately, I make regular trips to those states yearly on other business.

Richard Hull