Silver-flo™ Flux Powder is a basic lower cost brazing flux suitable for use with silver brazing filler metals. As such it does not exhibit all the activity and characteristics of other brazing fluxes. It is however, suitable for use on all of the common engineering materials (copper, brass, mild steel and stainless steel), but not aluminum. JM special purpose fluxes are required when brazing aluminum bronze, certain grades of stainless steel, tungsten, molybdenum and tungsten carbide or where protracted heating is involved. Flux powder should be mixed with water and a few drops of liquid detergent to form a thick paste. Paste should then be brushed onto the joint surfaces before assembly. Further flux should then be applied externally either side of the joint mouth. It is good practice to mechanically clean and degrease the joint surface before applying flux. Heat slowly and evenly to the brazing temperature, without local overheating. Use the flux as a temperature guide - it will become clear or opaque as brazing temperature is approached. If blackening of the flux occurs this is often a sign of insufficient flux, overheating or flux exhaustion. Information provided by Johnson Matthey Metal Joining |