Hi Josh,
I have tweeked your photos a little to bring out more detail...
There are several options you can take with your coin, ( which I have no doubt will clean up nicely with some patience and hard
work!)
The best option would doubtless be to attack it with either a
dental pick, scalpel , pin or my favorite tool , which is a length of stainless TIG welding rod sharpened to a point on one end and a chisel blade at the other end... The trick is to only
work the tool up and away from the coin, thus ensuring you don't scratch the
patina..
If you are unsure about your skill then why not buy yourself a few
cheap uncleaned
Romans from fleabay and practise on them... ( or enter the never ending coin cleaning contest....
Cheap and very cheerfull!! ).... Chances are you won't find anything wonderfull , but even if you can remove the crud from a slug without damaging the surface then you will feel more confident attempting this job, and while you are practising this coin can soak in DW for a few weeks more, making your eventual job even easier..
If you realy don't want to go this route you could try
buying bamboo kebab spears, they are tougher than the nylon brush, but
still soft enough not to damage the
patina..
You might also try
Gringotts conservator mix.. I think Joe used to have this for sale in the coin store, but I know a quick
google search will throw up a truted supplier, and this does a wonderful job of softening hard encrustations without damaging
patina... I cannot personally recommend this product too highly!! It is much speedier than DW ( and I am currently using it on my
man faced
bull coin which I
hope to post progress pix of later today..)
Whichever route you choose, please post photos and keep us updated with your progress, and the best of luck to you!!