A good solder joint starts with the right flux. This collection of Water Soluble Soldering Fluxes are designed for use in the assembly of printed circuit boards (PCB's) and electronic components using wave solder machines, selective solder machines, dip solder pots or hand soldering. Alpha's 870-25 Touch-Up Flux is our top-selling flux for hand-soldering and allows for cleaning in either water or solvent.