Kester 24-7068-1402, 48 Activated Rosin Flux for cored solder wire was developed for lead-free applications to enable soldering of most common metals. 48 has performance characteristics far exceeding standard RA fluxes. 48 builds on the performance of its predecessor Kester 44 with “instant-action” wetting to provide fast and reliable solder joints. 48 is classified as ROM1 per J-STD-004.