So I grabbed my bottle of Metalizer burnt iron off the shelf a few days ago and was surpised to find a big hard rock inside, sort of resembling a real fat penny. It made a heck of a racket rattling around in their too! I wondered what would happen if I fill the jar half way with lacquer thinner and let it sit. Well to my surprise it came back to life. Looks new. Have not tried to airbrush it yet, but it looks fine. I did add a few drops of metalizer sealer to the bottle to give it some adhesion help -- not sure if that was smart or not at this point.. I'll give an update in a few days after I test it out...