Step 8 · Apply Solder to the Joint
Once the joint is hot enough to melt solder, remove the flame. Immediately touch the tip of the solder to the seam where the pipe and fitting meet. Do not apply the flame directly to the solder. The heat of the copper itself will melt the solder. Apply the solder to the bottom of a horizontal joint or to the side of a vertical joint. Capillary action will pull the molten solder into the small gap, completely filling the space between the pipe and fitting. For a 3/4-inch joint, feed about 3/4 of an inch of solder. You will see a thin, continuous silver ring form around the entire seam when the joint is full. Once this ring is visible, remove the solder.