Vic, thanks for your post. Soldering thin solar cells is probably one application that is more demanding than stained glass soldering. The thin glass will deform with temperature variations and in extreme cases will crack. Pressure to improve heat flow will also crack the cells on contact. Soldering at a temperature only 20 to 40 degrees C over the melting point of lead free solder eliminated these defects. I had heard that stained glass fabrication had similar problems with glass cracking during soldering due to the higher temperatures most manufacturers recommend when switching to lead free solder. I am looking for some help and determining if our assumptions are true. I am not pretending to know anything about stained glass soldering.
My guess is that the vast majority of stained glass people do not use lead free solder. If someone is cracking glass while soldering it is probibly due to their inexperence, not the soldering iron temperatures.