Hey all, I recently got this Maximinus sestertius for next to nothing. I have never worked on cleaning a sestertius before, and was wondering what the best approach is. Acetic acid, citric acid, sodium thiosulfate, sodium hydroxide? I'm not sure what to use..
Hey all, I recently got this Maximinus sestertius for next to nothing. I have never worked on cleaning a sestertius before, and was wondering what the best approach is. Acetic acid, citric acid, sodium thiosulfate, sodium hydroxide? I'm not sure what to use..
First and foremost, soak in distilled water for a few days. Then a light scrub with an old brush. And NEVER use anything with the word acid on a coin. My fear is that your coins bronze disease is still active. But again, first you need to gently clean off the remaining BD, around the mouth and possibly temple. You can see the almost purple color that is a sign of BD scaring. Does it flake off when you rub your fingernail against it? Clean that crud off and then on to the next step in cleaning off BD. Search the archive cause it's been gone over ad nauseam.
You may be able to seal it using a Dremel with a conical or cylindrical felt attachment with a tiny smear of Renwax. That can often sort of burns in the surface of the bronze disease and stop it from spreading. Plus, using the conical felt attachment and a tiny smear of Renwax brings out some details of the coin. If you feel it is hopeless anyway, you could try a teaspoonful of Natrium Hexametaphosphate in 3-4 teaspoonsful of cold water in a non-plastic saucer, small jar or similar. The mixture gets hot on its own and can melt plastic containers such as yoghurt beakers. Use tweezers to remove the coin from the mixture after a few hours or overnight and rinse very well in cold water, brush it with an old, cut-down toothbrush. Repeat if necessary. Natr. Hex. does not damage the patina of coins. Note: it is NOT the same as salt, which will eat your coin and spit out dust... Never use salt on coins!!
I’ve never heard of natrium in any context other than Egyptian mummies! I will have to find some of this
I believe this is just a language thing. In English, we call it sodium but a number of modern languages adopted the Latin natrium. In either case, the chemical abbreviation is NA.
The chemical formula for the Nat. Hexa is NaPO3. If you have a real chemist shop near you, you could ask them to make you a small batch to test. My own chemist in the town near to me makes it for me. Just make sure you keep it absolutely dry. If you use a wet spoon to measure out your spoonful, the whole lot will turn rock solid in time.
Looks like it has some details hiding under all the deposits. Use a strong base like 20% ammonia to soften all that green stuff covering up the details.
