I thought I would post a few images of
Chinese cash coins in the process of being cleaned.
Like ancient
Roman and
Greek coins the
patina on
Chinese cash coins is important and can add substantially to the value.
Chinese collectors in particular can greatly value the esthetic qualities of the various colour combinations - cash patinas can include colours seldom seen in western ancients such as blue,
red, orange and purple.
However, it is also more common to find
Chinese cash that have been chemically cleaned, often done to a very high
standard, revealing the original metal. And interestingly, this is not considered by many to be as heinous a "crime" as it is with say
Roman coins.
It is also very common to find
Chinese cash where the raised surfaces - the calligraphy characters and the rims - are cleaned, sometimes even to shiny metal, while the fields
still have a
patina or even a thick crust.
As such, in many loads of
bulk Chinese cash few if any coins require much cleaning beyond a nylon brushing or picking the dirt out of the characters.
However, sometimes you encounter real "crusties" among the
bulk coins and this can be very exciting as they are truely unsorted - they can not be identified until cleaned. These coins have a very hard, but usually smooth, crust on them. It can be quite thick.
Most websites I have seen that address cleaning
Chinese cash recommend chemical cleaning. However, being primarily a cleaner of LRBCs, I like to attack them mechanically.
Scalpel/x-acto knife is of some use but may main weapon is the steel pin - usually a sewing needle - which I keep
sharp with a whetstone.
Below is a before picture of four Northern Sung Dynasty (my guess based on
fabric and rest of the
bulk lot)
Chinese cash. Note the very thick, hard
patina.