So, there is a Very cheap Denarius of antoninus pius selling, but its Very dirty and i was wondering if i could Clean in and How, and If It Will turn out great.
I would soak it in acetone, and after that distilled water. You may also try to gently roll (not rub) a Q-tip over the encrustations on the portrait. You may find that it need several rounds of soaking in distilled water.
Acetone will do nothing for this coin; it is only good for removing stuff like adhesives or PVC gunk. I would soak this in ammonia or citric acid and scrub and rinse and repeat as needed.
I've had great success with Sodium Thiosulphate and warm water, you just scoop 2 teaspoons of the Thiosulphate salt crystals into a glass bowl and add warm or hot water, leave the coins in there for 30 minutes to an hour then try to rinse the coin with water at your kitchen faucet. If only some of your deposits wash off right away, reheat the glass bowl with the solution in the microwave wave again to make it warm or hot. Place the coin back into the solution and repeat the same process again. If this process fails. Use a bowl of warm water and dampened and softened worn end of a toothpick to gently prick at the deposits (DO NOT APPLY MUCH PRESSURE) do it softly and slowly. Everytime you think you removed some deposits just swish the coin around in the bowl of water and try again. The longer you soak the coin in the Sodium Thiosulphate solution, the more the deposits will weaken and soften into a clay or dirt like texture. Afterwards use faucet water to flush the coin to get more deposits off. If you still can't get the deposits off, you may soak the coin in Sodium Thiosulphate for a few days to a week. Or you may have to resort to using a weak acid like heated lemon juice/citric acid to eat away the deposits.
Sodium thiosulfate will dissolve horn silver. Since this is a reaction product of the silver of the coin, it might leave a divot when removed. Before trying that, I would try a soak in water (start with it boiling) and brushing with a stiff bristle tooth brush and perhaps some picking with a toothpick.
Yes you are totally right, there may be some consequences for the Thiosulphate method, but so far I've had very good results on several coins I have worked on, not much in terms of pitting spots in the areas. Chemically it seems Thiosulphate does react a little with these reddish deposits (iron oxides ect.) even if it's not horn silver, the red deposits seem to soften up a lot after exposure to the Thiosulphate solution as opposed to just boiling water. The tooth pick method does work but you have to be very patient and extremely be careful otherwise there is a risk of scratching the coin. Instead of scraping with the toothpick, tapping very lightly with the tip is better and the tip has to be dampened and slightly flattened so it won't be too sharp. Here is an example of a before and after on a coin I worked on, I'm very happy with the results of this one. The toning is hard to photograph but it wasn't affected by the process, the toning is still there under better lighting.
