I am no expert in lead, and I certainly wouldn't put it on any of the functional work that I do. Its just not worth thinking about from a liability standpoint, and the lawyer in me says "Who knows what some kid would do, even with a sculpture?" That said, I have read some older ceramics books that contained extensive discussion on using lead in glaze. At some point I read The Potter's Craft by C.F. Binns, and I recall that he discusses in detail the chemical formulas and differences in red lead and white lead. I believe he had a variety of recipes for lead glazes. You can get electronic copies through google play.