A liquid solution for oxidizing the surface of metal. It is not an acid and not considered a hazardous material, but it does STINK so use in a well ventilated area.Best for copper. Also works on silver and silver filled. Does not work with brass, nickel silver, gold-filled or aluminum.Learn how to work with Liver of Sulfur in a safe manner as well as more about storage, disposal, protective equipment, and spill-handling procedures by clicking on the Materials Data Safety Sheet. I really prefer the liquid Liver of Sulfur over the solid rock form because you don't have to wait for it to dissolve. Also, every time I have purchased the rock form, it has expired before I had a chance to use it all. Liquid Liver of Sulfur will weaken over years but if you keep it super airtight and in a cool dark place, it will extend the shelf life. Personally, I haven't seen it happen (my bottle has lasted a long time) but in theory, there is the potential that it could weaken over time.This is a 4 ounce bottle of liquid concentrate. You will be diluting only a small amount with water . The bottle has instructions for using it with copper, so we have included our own instructions with the bottle for using it with silver.