As many may have already assumed from the name, in native metal soldering, the process of fusing parts together is accomplished without solder, or without the use of another, more easily melted metal. It occurs either by fusing the molten ends and edges of the parts to be soldered, or by using molten pieces of the same metal.
Soldering Procedure:
Nugget soldering is the strongest, both because the fusibility and expandability of the metal from heat are the same everywhere, and because no galvanic currents are formed here, which often spoil the solder when using dissimilar metals. Therefore, metal vessels intended for storage of various chemical substances or exposed to the action of constant heat, dampness, acids, etc. should be soldered by native soldering. After the introduction of hydrogen flame into use, it became possible to melt and therefore to solder all metals in general, but it is still practically suitable only for iron, platinum and lead.
Native soldering, or iron welding everyone has long known is usually done by blacksmiths.
For joining pieces of platinum:
Their soldered edges should be heated with a soldering tube and hydrogen flame to a bright red glow; sprinkling the joint with a small amount of any antimony salt accelerates the connection; to remove the excess antimony, the joint is then heated to white.
For soldering lead:
To solder lead, such as two sheets of lead, the edges of the sheets are cleaned and scraped to brightness, smoothed with a wooden hammer, overlapped one on top of the other to a width of 1/4 inch, pressed against each other with blows of the same wooden hammer, and then heated with a blowpipe and hydrogen flame until soldered.
If you want to solder a cylinder from sheet lead (for example, for a vessel), it is better to do it this way:
- roll the sheet into a cylinder of the desired size;
- clean the edges of the future seam and overlap them as above;
- For binding, glue (glue) along the seam on the outside with a strip of thick wrapping paper 2…3 inches wide (if necessary, two strips – one on top of the other);
- inside the cylinder, glue two strips of the same paper, 1 inch wide each, along the seam, so that in the middle between the strips, a space of 3/8 inch wide is left above the seam, at the edge of the inner joint.
When the paper is dry, place the cylinder seam-side down on a heap of dry sand on a slightly inclined plane, i.e., so that one (upper) end of the seam is a little higher than the other (lower) end. Then select a flat and smooth block of wood 3/8 inch thick, 3/4 inch wide and the length of the seam of the cylinder, lay it on the free space between the strips of paper, along and along the edge of the inner joint; as the width of the block ( 3/4 inch) is somewhat greater than the width of the gap (3/8 inch), the edge of the inner joint will be slightly covered by the edge of the block. Cover the bar tightly with damp clay sand, 3 inches wide on each side; pressing the sand down well, remove the bar and clean the groove from the sand.
At the lower end of the groove (and the seam) make a hole in the sand on which the cylinder is lying. Sprinkle a fine powder of rosin lightly over the joint; melt a piece of lead in an iron ladle and, when the molten lead is heated to redness (visible in the dark), pour it into the groove at the upper end for a few seconds, with the excess lead flowing into the hole in the sand. Try a smooth stick: if the edge of the inner joint on the feeling is uneven, continue to pour lead, as said; when the edge of this will become smooth (a sign that it is well heated), seal the lower end of the groove with a piece of clay and fill the groove with molten lead to the top; let solidify, remove sand and paper, cut, scrape off excess lead, level, smooth. In general, it should be said that nugget soldering is very difficult and requires great skill.
