Is This Constantine The Great?

You are correct with Constantine the Great
Obv:- CONSTANTI-NVS MAX AVG, Rosette-diademed, draped, cuirassed bust right
Rev:- GLORIA EXERCITVS, Two soldiers with two standards etc.
Minted in Nicomedia (SMNS in exe)
RIC VII Nicomedia 188 rated r1 by RIC

I would agree that you have overcleaned the coin. The olive oil will typically not penetrate the patina but will soften any dirt. It would appear that you have been slightly too aggressive with your brushing. Did you use a nylon, brass or steel brush? Most people will use a nylon or a soft brass brush (as used for brushing velvet).

Regards,
Martin

As a long time uncleaned ancient coin cleaner, I strongly recommend that you stop using olive oil (OO) and switch to distilled water (DW). If you can get de-ionized water, that's even better, but you can get DW at any grocery or department store and it will work fine. Do not use tap water, spring water or bottled drinking water--make sure it is distilled.

DW is much cheaper than OO, much less messy, does not leave an oily film, is more effective, and, most importantly, will not harm your coins or turn them black. OO is very slightly acidic. For short term use this is not a problem, but if you are letting the coins soak for 6 months, the acid in the OO will eat away your patina, which is what happened with your coin. Have you ever noticed the OO turning green or blue after the coins have been soaking in it for a while? That's copper that has entered the OO and changed its color. Guess where the copper came from. That won't happen with DW; I've left coins soaking in it for over two years--okay, the encrustations were really stubborn, and I have no life--without any ill effects. Save yourself a lot of money and mess and switch to DW.

Glenn Simonelli
http://mysite.verizon.net/gsimonel/

Thanks for the tips guys...

Glenn....I did notice the OO changing colors,but never thought much of it...Im going to take your suggestion and TRY DW on the next batch of uncleaned coins I get...

I just thought that oil would soften the dirt and grime better than water did!

Ditto on the homepage..nice