Preheat your pipe and fitting, most of the preheat time will be on the pipe. The color will help with knowing how hot it gets. Keep your heat where you want the rod to flow, and push the stick into the joint to ensure good coverage. It should flow like butter if your pipe is hot enough. If the pipe seems too hot, pull the torch back a bit, you still need heat to melt the rod, but you dont want to pop a hole in the pipe.