I am looking for a good copper and brass pickle. Is Sparex good? Or is it better to use Sulfuric acid and water? I have the articla by bu Bill Seely. He says to use a basic sulfuric acid solution prio to using hs formulas. %5 to %10. I assume that means a solution of 5 to 10 percent sulfuric acid and water. Is that correct? Is that the best pickle? or is there a better and safer method?