Picked up a very nice Caracalla from our very own Victor.
Caracalla. AR Denarius, A.D. 214 (17x19mm 3.2g) ANTONINVS PIVS AVG GERM; laureate head right.
P M TR P XVII COS IIII P P; Jupiter, bare to the waist, standing l., holding thunderbolt and scepter: at feet, eagle. RIC IV Rome 240
I went ahead and cleaned it:
1. Three - 15min soaks in Ammonia and then lightly brushing with a used soft toothbrush (I used a waterpick brush - nice and small and easy to use on small areas..
2. Soaks in a lemon and distilled water mix and picking with a wet blunt toothpick and a cleaning Pencil (Le Crayon a Andre -Fiberglass Coin & Artifact Cleaning Pencil) . I also use a Q-tip (cotton ear swap to remove the debris. While doing this, the coin should always be wet. I dip my finger in the mixture and put a a dab on the coin before touching. I also used straight lemon juice on some spots.
Notes: I don't recommend using the toothpick and cleaning pencil unless you know what you're doing and have had some practice. I use a tripod magnifier (It's like a mini-microscope) and only touch the encrustation and I mean touch - NOT scrape. It's a long process, but it's relaxing and satisfyng for me anyway.
I'm happy with the overall results, but have issues that I knew were going to come up. The toning in the heavily encrusted area is lighter than the unaffected areas. The "rust" stains on the reverse are stubborn and I guess can be removed with further effort. But, I'm leaving it for now.
Thanks for looking and if you have some before and afters - please share.