On this one - flush with water, preferably hot water several times, let stand for a few minutes with the void full of water to give it a liitle time to work (dissolve the caustic) then remove the water tracies by flushing with acetone ( acetone loves water), warm barrels and flush with a light oil. Remeber acid will remove hot bluing and that is why it it not used as a neutralizing flush after a hot blue. JMTCW ---John Can.