"mypublicident," "me," and "werecow" are precise. Glass isn't a liquid...and this is not crystal. Glass has a crystalline diffraction trend, regardless of the undeniable fact that it's not crystal. in accordance to window glass viscosity, it is going to in basic terms pass some nanometers over a century -- not adequate to reason the thickness you notice on the backside of a window pane of an previous development. back then, domicile windows have been made with the help of spinning a disc of glass, inflicting the middle to be thicker than the outer rims. whilst the glass became shrink, the window makers might place the thicker side down for stability. additionally, any vertical striations you additionally can see in the comparable previous window pane is not greater data that cup is unquestionably a liquid. As rainwater fell around the brick, it might substitute right into slightly alkaline and then run down the fringe of the development onto the glass...and progressively etch the glass. desire this enables!