Lead Lampshade

Several years ago my mother-in-law asked if I'd try and fix an old lamp from her childhood - somewhere between 1920 and '25. When received the shade was half caved in, broken in 8 places and the paper liner ripped and stained. At first I doubted anything could be done but upon closer examination discovered the framework for the shade was made of cast lead. With a lot of careful bending, twisting and soldering the shade was returned to its original shape. Old enamel paint was chipped off with a sharp knife, repainted, antiqued back and sealed with a clear coat. The paint on the flowered portions is for the most part all original. A wooden base was made to help stabilize this rather top heavy lamp and it was rewired with period style cord and plug.

I am an antique fire extinguisher person so know nothing about lamps. An old school lamp repair person I talked to had never seen a shade made of lead which makes me curious about the background on an item like this. Would appreciate any insight anyone has on this type of item.