If you want to etch metal clay, this is the way to go. Etching with ferric chloride or nitric acid is impossible with metal clay as the chemicals are absorbed by the clays and continue to etch after removal. With the E3, the etching process stops when the power is turned off. It is also safer, cleaner and more economical, in the long run. The copper sulfate used with the E3 is reusable and can be re-hydrated over and over again. The E3 produces crisp lines and the resist doesn't lift off like with ferric chloride. I've etched multiple pieces at one time and they have come out perfectly. Time wise - it's similar to ferric chloride but the clean up is much, much easier. Copper sulfate is less toxic and less hazardous than both ferric chloride and nitric acid. In my opinion, the E3 is the best way to etch copper, brass, silver and metal clays.