The Kester 959T is a no-clean, non-corrosive, liquid flux that is designed for the wave soldering of conventional and surface mount circuit board assemblies. 959T was developed to minimize the formation of micro-solder balls during wave soldering operations. 959T leaves evenly distributed residues for the best cosmetic appearance. - This flux contains a small percentage of rosin (0.5%), which improves solderability, heat stability and surface insulation resistance. 959T offers the best wetting and the shiniest solder joints of any no-clean, solvent-based chemistry.