going to stores to look for alcohol grandpa? what happened to being a role model for little children?
Is there a break point in grades where cleaning - if not too extreme - really doesn't matter much. For example below what numerical grade does the luster component become diminishingly insignificant for practical purposes? ( I understand that you can hurt ANY coin).
Not really. Even in G VG grades it matters. If you are talking about luster all by itself, meaning luster that has been worn off by normal wear, (as opposed to luster that has been worn off by a harsh cleaning), then luster becomes insignificant for all practical purposes in grades below XF40. That is because for a coin to be worthy of XF40 then it needs to have about half its luster left. For above XF40, more than half. Some coins in VF35 may have traces of luster left here and there, but as a general rule there not be much. And on some, none at all. Below VF35, it's kind of unusual to find luster still on the coin, except for maybe in the most protected areas like inside an O or 0.
I never really considered luster to be much of a factor in coins in less than XF40. Coins in this category have faced lots of environmental exposure and have picked up myriad scratches, so that I could not see the harm of spreading my VerdiCare over the surface with a cotton swab.
As I see it, and imperfectly probably, there are two ways of cleaning and two pitfalls. If you scrub, rub or wipe, you are going to leave scratches (might take a high power glass to see them, but they are there) and if you dip, soak, rinse, you still might dammage the surface through destroying luster or opening up pitts in the metal. I have seen mostly nice looking copper with grainy surface that just ruins the appearance.
The reason why you don't see in an American store may well be caused by different bureaucratic regulations, compared to my location here the US is more sensitive towards the use of alcohol. And yes it's available in practically pure form. Like Kentucky said if it contains secondary substances it's mostly water, dehydrated forms are available too, bordering 100% purity. You should also consider that absolute 100% purity is nearly impossible and even acetone is more like 99,5% pure. The type of person I've hoped to chime in, very good Kentucky. You should indeed write a book about cleaning of metallic surfaces with an underlying scientific systematic approach. The only other substance listed by the safety data sheet for the alcohol solution used by me is butanone (MEK - less than 1%). What do you know about its effects? If you want dual use alcohol why not this here: http://www.amazon.de/Primasprit-Weingeist-Trinkalkohol-Ethanol-4%vol/dp/B00CBDV5MG/ref=sr_1_6?ie=UTF8&qid=1376657738&sr=8-6
Whoo...good old PGA (Pure Grain Alcohol) we used to buy this in liquor stores under the brand name Everclear. Don't know if it is out there still or not. DON'T TRY AND DRINK THIS STUFF STRAIGHT! It will dehydrate you right now. The MEK you talked about was one of the solvents we used in the last place I worked. It is similar to acetone. One other solvent we used that would probably be good for cleaning (degreasing) coins was THF or tetrahydrofuran. These solvents are hard for individuals to purchase in the US because of the potential for abuse by breathing the vapors.
I have found a couple of heavy degreasers and cleaning solutions I liked for everyday use that I would try on coins... Unfortunately all are now illegal in California. I think you can still get one or 2 in Texas though.
And thanks again for your reply. The PGA was good for some fun time, eh? In fact both xylene and tetrahydrofuran are bit harder to get compared to some of the other solvents here too, but not entirely impossible. Their benefits are just negatively offseted by health risks and are not something I must use. It's a bit amusing, high concentrated ethanol is outlawed yet xylene is easily available.
I soak my flying eagle cents in baking soda and vinegar. They come out nice and pinkish. I see no scratches on them, even with a magnifying glass.
And by doing this you took away about half the value the coin had. The use of any acid on copper is a loosing deal.
I have a slight hunch that this particular member is something that starts with a T and ends with a "roll"... And I would think if they "came out pink" that it would be more than half the value lost...
Interesting, vinegar is 5% acetic acid and baking soda is sodium hydrogen carbonate. Mixing the two of them gives sodium acetate and carbon dioxide (hence the fizz) which is like soaking coins in saltwater. Hmmmm
And what does salt water do to copper, and silver, coins ? It corrodes them, literally eats away the surface.
I have recently consulted with a museum curator who has specialized in silver artifacts and has several published books on the subject. She says that proper polishing is essential for preserving silver, especially coins.