back into shape before proceeding with the work.

Tubing or pipes may be bent while being held between two flat metal
surfaces while at a bright red heat. The metal plates at each side of the
work prevent bulging.

Another method by which tubing may be bent consists of filling completely
with tightly packed sand and fitting a solid cap or plug at each end.

Thin brass tubing may be filled with melted resin and may be bent after the
resin cools. To remove the resin it is necessary to heat the tube, allowing
it to run out.

Large jobs of bending should be handled in special pipe bending machines in
which the work is forced through formed rolls which prevent its bulging.


WELDING

Welding with the heat of a blacksmith forge fire, or a coal or illuminating
gas fire, can only be performed with iron and steel because of the low heat
which is not localized as with the oxy-acetylene and electric processes.
Iron to be welded in this manner is heated until it reaches the temperature
indicated by an orange color, not white, as is often stated, this orange
color being slightly above 3600 degrees Fahrenheit. Steel is usually welded
at a bright red heat because of the danger of oxidizing or burning the
metal if the temperature is carried above this point.

_The Fire._--If made in a forge, the fire should be built from good
smithing coal or, better still, from coke. Gas fires are, of course,