The Kester 275 no-clean flux for cored solder wire was developed to provide superior wetting performance for hand soldering in the electronics industry. The chemistry is based on some of the same principles that have been safely used for years in mildly activated rosin fluxes. - The use of 275 no-clean flux results in an extremely clear post-soldering residue without cleaning. The unique chemistry in 275 was also designed to reduce spattering common to most core fluxes. 275 can be used for both lead bearing and lead-free soldering. 275 is classified as ROL0 per J-STD-004.