The longest lasting finish, but slower to darken than the liquid blues. Easy to use, it reacts slowly with the metal but builds up a denser finish that will outlast the liquid blues. Excellent for touch up or complete reblueing. Metal must be clean and free of rust and sealed with rust protection to enhance and protect the finish. A dark blue color may require three or more applications, but each coat takes only 30 to 60 seconds of work. Complete instructions on each tube. Apply with swab or Q-tip.