Go into a gunstore and look at the price of a brass wire brush. Close to $1. Look at the price of an acid brush (25 cents?) at any hardware store. Just went to a woodworkers' show in San Mateo (CA) and saw brass wire brushes at one dozen for $5.95. That's 50 cents each. Acid brushes (great for applying solvent and washing down parts) were packs of 72 for $5.