b. Electric iron. The electric soldering iron is a more convenient tool to
use if a 110-volt alternating or direct current is available (fig 22). This iron
is obtainable In different sizes (100-, 200-, 300-, and 500-watt). The 100- and
200-watt sizes are used for light work, the 300-watt for medium work, and the 500-
watt for heavier work. A variety of tips are also available for use on special
jobs. The electric iron heats quickly and remains uniformly hot until the current
is turned off, thereby permitting faster work than with externally heated irons.
If the electric iron becomes too hot for a given job, the current can be turned off
for a few minutes to allow the iron to cool to a suitable soldering temperature.
Automatic electric soldering irons also have been developed that have a
thermostatic unit, similar to that found in electric flatirons, to limit and
control the temperature.
a. General. The gasoline blowtorch (fig 23) is commonly used as a means of
heating the flame-heated soldering iron. However, with proper adjustment of the
flame, it may also be used as a soldering torch.