Old bronze coin turning green. Is there a way to stop the green from coming back?
Research bronze disease and archaeological preservation of cupreous metals.. simply covering the coin with Renaissance wax won't stop the progression..
It is my understanding that the British Museum uses Renaissance Wax to slow bronze disease, so it must be of some help. It may be something that cannot be completely halted.
You really need to research actual bronze disease..it can be stopped..but the wax definitely won't..there is more than one method..there is a method using zinc..and a method using cancerous agents as well.. I urge you to just start by reading about bronze disease to understand what it is..
If this is Chloride corrosion then it can NOT be stopped until ALL the Chloride is removed.
That is why it is called a disease. Sealing the object does not stop it.
Read the "Conservation of Archaeological Resources" PDF, section on "CUPREOUS METAL CORROSION" in this thread for details of what and how.
https://metaldetectingforum.com/showthread.php?t=263378
Thanks for the info guys!
I like sodium carbonate in my set up...and you can combine it with sodium bicarbonate to make your own sodium sesquicarbonate for artifacts..
I am in the process of soaking a bridal rosette and a clock part in a sesquicarbonate solution at the moment as well as some copper pieces. I figure a few days in that should help. I am going to try soaking in Benzotriazole and ethanol (some Everclear) mix for a few days as well to soak into the cracks and add a protective layer. Any thoughts for the last coat? I am going to post a thread in a few minutes as I am not sure if I should add an acrylic lacquer (water based) or clear enamel from Rustoleum (oil based) for the final of these bronze, copper, or brass pieces that are getting bronze disease from being dug up in a marsh/ sodium heavy area. Any thoughts?
I have Renn Wax but hate how much it costs. I plan to save and use only on colonial coppers and flat buttons. Just the little really old stuff.