Hi HH-NC. I think I can help you a little. I have dug 2 breast plates myself. First thing to make note of is that no two relics are alike. Even something as minuet as a bullet can be completely different from the same exact bullet only inches away. The ground works in mysterious ways. Your plate is different in every way, shape, and form, from the one below it. The bottom plate looks to be non-dug or possibly a very early find from the 1960's. Some do come out of mud looking like that, but that is rare. I'll be honest, your plate will never look like that. Sorry that's just how it is. Your plate, however, is a beautiful piece. You should appreciate that it is 95% intact. All the details are very sharp and it is barely damaged, bent, worn, or with holes in the brass. In its self it is a "rare" piece, I am jealous. My 2 plates unfortunately didn't have as gracious owners as yours did.
When it comes to cleaning them, you must be very very careful. I only touch my plates with distilled water and Q tips. Sometimes I will use a soft toothbrush and dental picks if needed. Your plate looks clean enough to me. You don't want to over clean because you risk damaging it. It is ok to leave dirt and under clean than over clean. One of my plates I soaked in the distilled water and brushed and brushed until I was satisfied with it and the other I never even touched with water. I just picked most of the dirt off and it came out perfect although it is still covered in dirt. It wasn't worth damaging it.
All in all it is your relic and you can do whatever you want to it, but in my honest opinion that is a remarkable plate and I wouldn't do anything further to it. Buy a nice case, lock it up, and through the key away before you make a mistake on it. I think most diggers would support my opinion. If you have any questions let me know and I can show you a pic or 2 of my plates if you'd like, but you really do have a great piece. I hope you can see the rarity and beauty in it in the shape that it is in. Thanks.
