Processes that have failed, or had little or no effect
1) Biox (see my biox experiment)
2) Soaking in straight hydrogen peroxide.
Some people have had success with this, usually
with the high concentration that can't readily be found
locally. I tried the typical 3%. It has very little effect.
Distilled water provides better results. The high
concentration can be painful if exposed to skin.
3) I must place German Baths in this category (Lye).
I have tried it a few times, with different concentrations.
When 1 in 20 coins comes out "nice", I must call it
a failure. I also ran into problems when encrustations
dissolved, and left hideous orange colorations
on the coins, which was quite difficult to remove.
Also, it can be painful if any lye comes into
contact with skin. It also will reveal pits and porousness,
and most likely eat away any patina. Short, less concentrated
soaks may provide decent results, but I gave up after
a large blister erupted on a finger from contact.
Someone has perked my interest in this, so shall be running another trial on it soon.
4) Cleaning chemicals such as CLR, the Works,
Orange Power etc. Little or no effect found. On a couple
coins that were affected, it ate through the patina quite quickly.
5) Oxy clean. I really haven't had any bad experiences with
this, used for soaking coins. I have had a couple coins
that the patina was removed, but was most likely due to
weak or fake patinas. If the water is heated, the results
are better. Also, a bit of lemon juice seems to clean the coins
better, when added to the oxyclean. They react together...
but lemon juice can easily eat away the patina, as well
as damage bronze. Short soaks are necessary with lemon juice.
But, soaks in distilled water and washing soda seem to yield
better results than oxyclean, and is much chepaer