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.
At some time a job may come along where a seam would have to be covered with a heavier body of solder for additional strength or weight. Or sometimes a seam is run where appearance counts and a decorative effect would be desired. For this purpose a bead seam is very good and it is not difficult to run if the following instructions are carefully carried out. For this seam a flat piece of sheet metal can be used and it must be very level to procure good results. It may be tried on galvanized iron, tinned iron, brass or copper which ever may be at hand. It will not be necessary to seam up the metal as this seam will be run for practice only. It should be 6" or 8" long but of course it may be longer if desired. The metal will have to be cleaned thoroughly. Clean a strip the length of the seam and about wide. After this cleaning is finished be very careful not to let the ringers or any other object come in contact with the surface. In order to run this seam with straight edges it will be necessary to use some sort of a guide. For this purpose a very good material is gummed paper which can be bought at most stationery stores. If there is some mucilage at hand the pasters, as they are called, can be cut from ordinary paper and coated with mucilage. These will serve as well as the commercial gummed paper. The paper should be cut into strips about 11/2 wide. Take one of these strips the length of the seam, and if gummed paper is used moisten the gum and very carefully place the strip up to one edge of the seam. This must be done in such a way as not to get any of the gum on the cleaned surface. If this should happen it will be impossible to tin where the glue has touched the surface. If mucilage is used apply it to the paper very sparingly to avoid any of it getting on the cleaned surface.
It will have to be decided now how wide the seam is to be made. It can be from up to 5/8" wide to suit the job. For this practice seam it can be made wide. Mark off 1/4" from the paster which has been applied and place the paster on the other edge. Be sure these paster edges are parallel or the appearance of the seam will be very poor if one end is wider than the other. A short piece of paster is put across the seam at each end.
No flux should be applied before the pasters are in place because the pasters would not hold on the flux. The heat of the copper would curl the paper up and they would fall off. Put the flux on after the pasters are in place. Be sure to use the proper flux for the metal which is used. The seam will now have to be tinned. Use a heavy enough soldering copper for this kind of a seam because it will have to carry enough heat to pass over the entire seam without reheating. If there is a pause it will leave a ridge across the seam. The tinning is done as it was in Lesson 1, using the flat side of the copper. Under the subject "Methods of Tinning Copper" it will be remembered that when filing the copper the edges of the point were not to be sharp. This precaution is taken for work where pasters are used. Moving the copper over the pasters would soon tear them if the edges were sharp. It can be seen that tearing the pasters will leave a very ragged seam.
The tinning can now be done. Only enough solder is put on to tin the surface. If it is put on too heavy some untinned spots may be covered and the seam if it were a real one would not be tight. When the seam has been perfectly tinned more solder is put on to make the bead. Hold the copper over the seam without touching it but not high enough so the solder will splash. Now touch a bar or strip of solder to the point. As the solder melts let a drop fall about every 1/4" all along the seam. The amount of solder that will be required can only be known by experience. This will soon be learned after a few seams have been run. Of course the wider the seam the more solder it will require. A drop about every 1/4" should be enough for a seam wide. The seam now looks very rough. Place an edge, not a flat side of the copper on the seam at one end and as soon as the solder melts move the copper along as fast as the solder will melt. .