this solution is non toxic, and can be used both for cleaning copper and brass,but also as a toilet/diaper pail/litter box etc cleaner/deodoriser. it can also be used to patina carbon steel knifes. You'll need White Vinegar, preferably the pickling one (7%), and plain old salt. that's it. go for a 70:30 ratio Vinegar to Salt. mix as needed, in whatever amount you like. the results are instant. dip your piece into the solution, remove , rinse and towel dry with soft cloth. once you've cleaned all your copper or brass, use the solution to clean toilets, diaper/compost pails, or to darkly patina carbon knives.