When soldering or brazing it is important that the technician does NOT melt the solder with the flame; USE THE HEAT IN THE TUBING TO MELT THE FILLER MATERIAL. Because _______ must be allowed to fill the space in the joint. When soldering or brazing it is important that the technician does NOT melt the solder with the flame; USE THE HEAT IN THE TUBING TO MELT THE FILLER MATERIAL. Because _______ must be allowed to fill the space in the joint. the wicking action capillary attraction natural at