The author had picked up Irwin pipe clamps and galvanized pipes from Anawalt Lumber on their first visit. They had since learned that pipe clamps call for black bar and had tested the difference between using galvanized and black pipes with the clamps. They found that the galvanization on the pipes breaks and flakes into serrated teeth when pressure is applied, creating a rough surface that damages the wood. The author switched to using black pipes to avoid further deterioration and will find another use for the galvanized pipes.