How do I clean a clogged spray gun?

I waited too long to clean my spray gun, and now the lacquer I was using has hardened inside it. Can this gun be salvaged?
—Frank Pruitt, Wichita Falls, Texas

In most cases, you can rescue your spray equipment, Frank. First, disassemble the gun and wash the parts in the appropriate solvent (lacquer thinner for lacquer, mineral spirits for polyurethane or varnish, denatured alcohol for shellac). Professional painters often soak their guns in lacquer thinner or methyl ethyl ketone (MEK) to loosen paint. If any of these fails to do the trick, try a dedicated spray-gun cleaning solution. Spray-gun cleaner softens oil and latex paint, polyurethanes, and other finishes, and it starts to work in a few minutes. (Don't soak O-rings, gland nuts, or other soft parts.)

What if you were using a catalyzed finish that crosslinks as it cures? At that point, says Bill Boxer of Apollo Sprayers, "Kiss the gun goodbye."