I was wandering the aisles of WalMart and stumbled across the stiffest plastic brush I have ever seen. The bristles are plastic so they should not harm your coin and the brush is a great size. See the accompanying photo above. The overall length of the brush is 7" and the brush head is 2 and 3/8" in length. The bristles measure 3/4" in width.
I have never seen a plastic brush this stiff. The item is called a "Grout Brush" and as I indicated I found it at WalMart. The price is .97 cents. It is large and very comfortable to hold. Please rush out, buy one and share your opinions with us. Thanks for reading and God Bless.. Jerry..