How Do You Use Flux With Solder?
When soldering copper pipe, proper preparations must be made to ensure the solder adheres properly. The most important preparations are sanding the pipe and applying flux. For solder to properly bond to copper pipe, you need a clean surface. The combination of sanding and applying flux provides that surface. Fluxes generally contain acid, which removes any residue from the copper pipe. It is applied in paste form, which helps keep it where you want it. Clean the end of the copper pipe thoroughly with sandpaper. This will etch the copper and leave it nice and shiny. Brush out the inside of the copper fitting with your fitting brush. Unscrew the lid to the soldering flux and pull it off. Notice there is a brush attached to the inside of the lid. This is for brushing the flux to the outside of the pipe and the inside of the fitting. Coat the brush with an ample amount of flux. Brush the flux on the outside of the pipe and the inside of the fitting. The flux should coat the pipe thoroughly
