The most basic bend is the right-angle bend. The key to making a good bend is to heat sufficient glass to make the bend, and also to prevent kinking of the glass. For a right-angle bend, mark the glass tube so that the portion of the surface placed into the fire equals two full diameters of the tube. For example, if 12mm tubing is to be bent, small marks should be made on the tube 12mm in either direction from the center of the bend, creating a heating zone of 24mm (Fig. 1).
Heat the glass in the crossfire, moving it back and forth uniformly while rotating the tube (Fig. 2). As the glass softens, balance the ends of the tube in your hands to prevent twisting or stretching of the glass. Before making the bend, raise the tube higher in the fire to apply more heat on the bottom, which will be the outside of the bend. Next, bend the ends of the tube upwards while using the blowtube to prevent the soft walls from collapsing.
A second method for making right-angle bends is the miter bend technique (Fig. 3). This method is used on uncoated tubing in countries where tubes are coated after bending is completed. Heat a ring of glass on a 45