English: Welding two glass tubes together. The tubes are made of lead glass and are used as filling tubes for neon lighting. The OD is 5mm and the ID is 3mm. The torch is a simple, handheld propane-torch, and the tubing is held right at the tip of the flame to avoid overheating the glass (which causes the lead to conglomerate at the surface, making the glass appear metallic). The welding is accomplished by heating the glass to red-hot while spinning the tubes to prevent cracking. Holding then at a slight angle, the edges are touched together and rotated to seal it together around the circumference. Then pressing to fatten the weld and pulling to thin the weld to the necessary 1 mm thickness, all while blowing slightly to maintain a tubular shape. This photo was taken the moment the two tubes touch.