This section is from the book "Applied Science For Metal Workers", by William H. Dooley. Also available from Amazon: Applied Science For Metal Workers.
The joints most commonly used by plumbers are the wiped and screw joints. The wiped joint is made by scraping and fitting the parts together and then pouring molten solder upon the place of joining. This solder, while still in a plastic condition, is wiped around the joint, with a moleskin or cloth pad. Thus a neat and reliable connection is made. The screw joint is made by cutting threads upon the pipes with stock and dies, painting the threads with white or red lead to make the joint tight, then turning each piece of pipe half through a coupling by means of pipe wrenches.
 
Continue to: