grizzly 2
But for the life of me, unless a bronze brush is already dirty, I cant see how it will create dirty patches unless there is still something there to clean out.
There black residue you see is from a reaction of the to metal rubbing against each other. It really is quite common, switching from the bronze/brass brush to a Synthetic Brush we stop that reaction...
These brushes work very well in lieu of the brass brush...
http://www.montanaxtreme.com/product...roduct=Brushes