This Oatey 1-7/10 oz. No. 5 Lead-Free Solder Paste is a smooth, non-runny paste that applies easily and spreads evenly. The paste cleans and fluxes copper piping to help provide uniform solder flow. This paste is safe for potable water applications. The self-cleaning formula is good for soft solder applications of copper tube and fittings in plumbing, HVAC, fire sprinkler and other systems.