In trying to identify a piece of metal by its surface
the material to a guessing game as to what type of
appearance, consider both the color and the texture of
material it is. Granted, it is best to make out a tag with
the surface. Table 6-3 gives the surface colors of some
all the important information as to the type of material,
common metals.
of that material. Even then, tags are subject to being
lost. Therefore, let us look at the various ways to
IDENTIFICATION TESTS
identify the material according to surface appearance
and identification tests.
If the surface appearance of a metal does not give
enough information to allow adequate identification,
IDENTIFICATION BY SURFACE
metal identification tests are necessary. A number of
APPEARANCE
such tests are used. Some of these tests are complicated
and require equipment that you are not likely to have.
Others, however, are relatively simple and quite reliable
It is possible to identify several metals by their
when performed by a skilled person. The following tests
surface appearance. Although examination of the
are the most common for shop use:
surface does not usually give you enough information
to classify the metal exactly, it will often give you
Spark test (with the power grinder)
enough information to allow you to identify the group
to which the metal belongs. Even this much
Oxyacetylene torch test
identification is helpful since it will limit the number
of tests required for further identification.
Table 6-3.--Surface Colors of Some Common Metals
6-14