Step 7 · Heat the Joint
Unroll about 8-10 inches of solder from its spool and bend the first inch at a 90-degree angle for easier application. Light your propane or MAPP gas torch with a spark lighter. Adjust the flame to have a blue inner cone about 1-2 inches long. Begin heating the joint by applying the tip of the blue inner cone to the middle of the fitting. Do NOT heat the pipe directly. Move the flame around the entire circumference of the fitting to heat it evenly. The flux will begin to bubble and smoke, which is normal. In about 30-60 seconds, the copper will be hot enough to melt solder. You can test the temperature by briefly touching the solder to the joint on the side opposite the flame. If it melts instantly, the joint is ready.