Today I disassembled my Iwata HP-CS for thorough cleaning. The last time I disassembled it was February and since then I've had at least 10 painting sessions with it. I've been using Don's pump action method for a couple months.
There was hardly any paint inside the AB. After wiping the needle with lacquer thinner, I only noticed a faint line of paint residue on the cotton pad. Before using the pump action method, I saw a thick line of paint residue. I'm totally impressed. Kudos to Don Wheeler for coming up with his brilliant pump action idea!