Staining Stained Glass?

Paint used to be made out of crushed glass and something like urine. Stained glass wasn't actually stained until the thirteenth century. They came up with this idea of kind of painting it with this paint they made. And all that does is add thes ding, which i didn't realize stained glass involved. The black lines that you see that create the kind of textures and all the shading which makes a lit more realistic. All just in brown and brown and gray.