The metal
must be just below that point at which small sparks begin to be thrown out
of the fire and naturally this is a hard point to distinguish. At the
welding heat the metal is almost ready to flow and is about the consistency
of putty. Against the background of the fire and coal the color appears to
be a cream or very light yellow and the work feels soft as it is handled.
It is absolutely necessary that both parts be heated uniformly and so that
they reach the welding temperature at the same time. For this reason they
should be as close together in the fire as possible and side by side. When
removed to be hammered together, time is saved if they are picked up in
such a way that when laid together naturally the beveled surfaces come
together. This makes it necessary that the workman remember whether the
scarfed side is up or down, and to assist in this it is a good thing to
mark the scarfed side with chalk or in some other noticeable manner, so
that no mistake will be made in the hurry of placing the work on the anvil.
The common practice in heating allows the temperature to rise until the
small white sparks are seen to come from the fire. Any heating above this
point will surely result in burning that will ruin the iron or steel being
handled. The best welding heat can be discerned by the appearance of the
metal and its color after experience has been gained with this particular
material.
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