just found this thread. Is it by choice that you use 3/16 Wayne, or is that so it more closely replicates the original lamps?
Joan, I gave Rebecca a generalized reply based on most of the people working on or selling Tiffany reproduction shades. 3/16" foil works well with most forms of art glass but not very well with good rolled glass like Kokomo and others. But that is just the tip of the iceburg.