Can I still save these or are they already gone.
I have read already the 2 threads on zinc coins and searched the web for some ideas, but I'm still not sure if I can save these coins in the picture.
Any help would be appreciated, someone who has already tested some cheap coins.
Can I still save these or are they already gone.
I have read already the 2 threads on zinc coins and searched the web for some ideas, but I'm still not sure if I can save these coins in the picture.
Any help would be appreciated, someone who has already tested some cheap coins.
Thanks
I'm always interested in old zinc coins, may you want to swap some just let me know.
I have tried an experiment with two other zinc coins i soaked them in vinegar for about an hour then rinsed them after rinsing them i soaked them in olive oil and the results are not bad i will post pictures later.
I really would like to salvage / preserve as many as i could of the above 5 coins as they are good dates
I have a number of the same coins, dug up from the battlefields of Eastern Europe and as such in similar poor conditions. I think I shall try your acid bath on a couple and see what happens, these are now too expensive to just bin (currently retailing in the UK for about £1 each).
Okay, the problem of using acid to remove zinc bloom is that zinc dissolves in acid. Which may not be a problem for cleaning zinc dustbin lids and similar items (it has long been a household hint that zinc utensils etc can be cleaned by rubbing with a freshly cut slice of lemon).
Zinc bloom (that white encrustation) is susceptible to heat. Initial experiments suggest that heating it over a hot flame cause the bloom to blacken and can then be rubbed away with a finger nail or stiff nylon brush. Bearing in mind that one does not wish to overly scratch the underlying zinc, but equally that this is an attempt to revitalize an otherwise seriously damaged coin, and as such some counter damage is not going to matter, its a matter of getting a balance.
WARNING! Zinc is a metal and conducts heat! DO NOT hold a zinc coin with the fingers directly while heating - use a metal clamp like 'helping hands', and cool off the hot coin in clean cold water immediately after heating!!!!
Remember also, that zinc reacts with both air and with water quickly to form a thin layer of non-water soluble oxidation (zinc bloom), and as such any cleaned zinc coins will soon tarnish if re-exposed to the atmosphere or damp conditions.
Quote: Matt_Probert... WARNING! Zinc is a metal and conducts heat! DO NOT hold a zinc coin with the fingers directly while heating - use a metal clamp like 'helping hands', and cool off the hot coin in clean cold water immediately after heating!!!!
...
Matt
Since zinc reacts with water to form zincoxide, I think it might be a better idea to cool the coin in oil. (This is standard procedure for hardening steel alloys). This may cause some colour changing, but so does the heating...
Something to try on low value coins...
Another hint : do not use an Industrial type of burner : coins will fall apart...
Tony
Quote: tony.cSince zinc reacts with water to form zincoxide, I think it might be a better idea to cool the coin in oil. (This is standard procedure for hardening steel alloys). This may cause some colour changing, but so does the heating...
Something to try on low value coins...
LOL!
You were joking weren't you? Very hot metal+combustible material=Fire
And the heating doesn't change the colour of the zinc coins, unlike bronze coins and steel coins.
No, I wasn't joking about cooling in oil. Yes, it may cause a little flame, but if there is enough oil, that's no problem !!
I also tried heating coins with a roofing-burner (don't know if that's the correct English name : device used by roof workers to melt bitumen roof coating ) : this caused my coins to simply disintegrate...
