I have a couple batches of cast bullets with a white powder on them. I tried just ignoring it, but my customer noticed and made an inquiry, so I went back and scrubbed, the stuff was stubborn. The best way I found to get it off was CLR and a brush, but it was still stubborn. Any recommendations? I just opened two more boxes and I have more of this white dust on the fixtures. The boxes were sealed well, I assume it's from the foundry.