I use the kitty litter on top of the melt to keep down the oxidation, and help maintain the heat. I use a piece of dowel to stir the mix, as it puts a carbon base completely to the bottom of the pot. No one has been able to convince me that something put on the top of molten lead and stirred around with a spoon or what-not, is going to flux the metal in the botton of the pot. Specific gravity, you know?
When melting big amounts to make into ingots, I use old motor oil, candle stubs, saw dust, and what ever is in the floor sweepings out of my shop. That works good, as I can clean the shop(hell of a mess, usually) while waiting for the WW's to melt. I dump the sweepings in the cut off propane tank with the lead to stir in. However, I think this may also be a waste of time.
Take into consideration all the tire labels, Copenhagen and Skoal spit, rubber air spiquets, dog pee, and dead mice and such that finds it's way into those buckets full of WW's.
Lotsa carbon there!