Last time I cast zinc WW didn't exist . Now reading here about them & how to spot them, I was going thru a 80 lb bucket of nice clean & new looking WW. Using the scratch test was easy to find std WW. However many with square ends that seemed very hard when dropped on cement , don't have a ringing sound. They seen to have a frosty/shiny coating of some sort on them . I am running about 60%+ reject rate. This seems a bit high. Will try to remove the coating & see whats there tomorrow. Has anyone else ran into this ??? Tks for any help. Russ.