This section is from the book "Soldering For Workshop, Farm And Home", by John Bonert. Also available from Amazon: Soldering For Workshop, Farm And Home - Information On Soft And Hard Soldering - Projects For The Workshop Explained And Illustrated.
The usual method for joining lead pipe is by wiping a joint. This is an art which the average craftsman has not mastered. Lead pipe can be joined by soldering as well as by wiping. This soldered joint on lead pipe is called a "cup joint" and Figure 8 shows how the work is prepared.
The male end of the joint must fit tightly into the flared end to prevent solder running through into the pipe. The flare must be large enough at the end to receive a fairly heavy body of solder. The flare can be made by hammering as the pipe is revolved or a top may be used. A piece of hardwood can be pointed on the end and used the same as a top. The male end is best tapered with a blacksmith's or wood rasp. When tinning this cup joint it is best to use the copper in a more vertical position so the point will go down into the flare. After the tinning has been done and the joint is to be floated don't forget that touch of tallow candle over the joint which gives the solder that smooth bright finish. Be careful not to have the copper so hot that it will melt the lead.
The drawing shows the use of ordinary shoe blacking as a guide instead of pasters. Pasters may be used but it will be a little difficult to apply them to the lower edge of the joint on account of the curved flare. While this soldered joint is not as heavy as a wiped joint it will be just as pressure-tight.