GALLIENUS TETRADRACHM

[ChefStu22]

Sorry guys this is another one I am struggling to pin down, whilst I'm asking about this coin does anybody know the best way to get rid of the green and to stop it coming back, as it stands it only affects two of my coins but it keeps coming back!!!!

[shanxi]

It's a year 14 like this:

https://www.acsearch.info/search.html?id=32006


If the green material is coming back it might be bronze disease. Remove it an use BTA to avoid that it is coming back again.

[ChefStu22]

Firstly thank you with the help with the ID of the coin trays perfect, and secondly I think that's what it is, sorry for my ignorance what is bta? Cheers Stuart

[shanxi]

BTA = 1H-Benzotriazol

It's a  corrosion inhibitor for copper and its alloys. You can buy it as solution or solid.

[ChefStu22]

Excellent thank you Shanxi

[mauseus]

Hi,

Word of caution, BTA is toxic and requires care in handling it.

Regards,

Mauseus

[ChefStu22]

Evening Mauseus, yeh indeed after a quick look over the Internet its fair to it would to appear to need handling with care, have either of you guys had any experience in using it? Cheers Stuart

[shanxi]

I used it on some bronze coins after manualy removing the  bronze disease. The BD never came back.

I used a 3wt% BTA (1H-Benzotriazol) solution in pure (99.9%) Ethanol. You can also use water, but Ethanol wets the coins surface better. I simply put the coin for some minutes in the solution, then removed and dried it with some  absorbent paper. In the end the amount of BTA on the coin is so low that you don't see it.

Of course it is a good idea to use gloves and eye protection.


In winter you can also go to the next airport. BTA is one of the main agents in the solution for deicing aircrafts. 
https://en.wikipedia.org/wiki/Ground_deicing_of_aircraft

[ChefStu22]

Cheers I'll see what's available to order in the UK and take it from there cheers for the information and help