I heated up the Dutch oven and began to fish through 1/2 pail of WW last night. I have always spent a lot of time sorting through all of the weights, looking for Zinc and trash. After about five minutes of examining each weight, I made a drastic decision.
I kept the heat on low, just enough to melt a lead WW when placed in the pot. I carefully picked enough lead WW out to fill the pot with about 1/4" of melt. There were lot’s of rubber grommets and valve stems in the pail, so I tested a piece of rubber to see how fast it would melt, but it didn't - amazing!
After that, I held my large ladle over the bucket and filled it with a handful of WW, picking out only the tape on weights, and whatever rubber grommets, valve stems, etc. were on the top and easy to pick off. (Using the ladle is an easy way for me to add weights to the melt without any splash.)
After each two or three ladles full, I skimmed off the garbage, including the unmelted zinc weights and unmelted rubber stuff.
I was a bit paranoid during the process about the possibility of melting Zinc, and would occasionally put a known Zinc weight and a lead weight into a ladle full of melted lead and let the ladle float on the melt. The lead would melt, and the Zinc would just float around.
Before long, the half pail was all melted, and I had a pile of debris. After cleaning up, I poked through the debris and found a nice selection of Zinc WW and unmelted rubber parts.
My yield was 60 lbs of clip on ingots, in record time. I stuck the 10 lbs of stick ons into my stick on pile for another day. Not too bad for a free WW pickup