There's really no need to plug or urethane the barrels if you're just doing bluing. It's necessary when you're etching Damascus, Twist, or Laminated barrels.

Dehumidifer water works as well. I suspect that water from one of those filter pitchers would work also.

Last edited by Ken61; 02/18/15 08:07 PM.
I prefer wood to plastic, leather to nylon, waxed cotton to Gore-Tex, and split bamboo to graphite.