This is the coin I am working on now. The first photo is the before. The second is the current status. I still have a little work to do. Valentinian I, AE3, Siscia. AD 364-373. 2.63 g. DN VALENTINI-ANVS PF AVG, pearl diademed, draped, cuirassed bust right. SECVRITAS-REIPVBLICAE, Victory walking left, holding wreath and palm. Star over P in left field, M in right field. Mintmark: Gamma SISC. RIC IX Siscia 15a, type xvii (a)
Is it safe, value-wise, to clean Roman, biblical coins of the green patina? If not, should you clean Roman coins of environmental damage? If so, how?
Thanks. I soak a couple of days in Acetone and/or Peroxide 40 Vol. Lightly brush between soakings. Then I put it under my stereo zoom microscope and very gently clean it with various tools. Diamond tip, light brush, etc. Then soak some more. I keep doing this until an image appears that I can identify. Even slight identification so I can continue knowing where the devices of the coin are. When I have an idea of what I am dealing with I can continue with some assurance that I am not going to remove any detail.
There are many posts on the Ancient Forum as to cleaning the bronze rot (green). There are also many posts on preserving and protecting a coin when you have finished. I have only been doing this for about 2 years. Every time I clean one and post here I learn more. Therefore, I don't want to give "expert advice" as yet. Get into the Ancient Forum and learn from the real experts. Welcome aboard.