Rectorseal 14010 4-Ounce Nokorode Regular Paste Flux Cleans and fluxes in one operation saving time and money Special oil base protects the solder joint against corrosive attack It's non-aggressive formula is ideal when used on copper and brass fittings Lead free and acid free-safe to use on potable water systems When heated, it reduces surface tension and allows the solder to flow easily and uniformly into the joint