Chris it's just a standard fire assay using a full electric oven. As far as sulfides we preroasted a batch for 2 hours and very little change or sulfur smell came out. That is when we put it under a high powered microscope and saw it more resembles metal compared to sulfides. No nails were used in assay. We double checked to make sure all lead was removed by recovering the metal in lead for a 2nd time using a new cuppel it only lost .1 grams from a 18+ gram button. The lead should of removed any impurities. When we hit it with a hammer it didn't shatter it more had a small dent.