Many people rinse the brush frequently, either in a bottle of something like paint thinner or acetone, or spray it off with brake cleaner. Same end result being to clean the brush. Rinsing the brush has the added benefit of longer brush life, as copper solvents really eat at cleaning brushes. Keep in mind, if you have copper cleaner in the bore or on the brush, it will look like copper on a patch.A couple of decades back, I started brushing after short stroking several solvent laden patches through the bore. The idea is to only use the brush for what a patch will not remove, and thereby significantly reduce the amount of abrasive particles carried by the bristles as they do their work. When I am finished brushing, I draw that rod, and the brush mounted on it through a wadded up paper towel to remove residue from both. It actually works pretty well. It takes off of most of the solvent which contributes to brush life. After brushing I run a couple of more solvent patches, and then let the barrel sit wet for a while, before running another pair, and then drying.









