TB 43-0213
(1) "Rustproofing" and "undercoating" are not
(6) Vehicles and trailers treated with rustproof-
ing materials should not be steam cleaned or cleaned
the same. Rustproofing is the application of a rust
with solvent. Such cleaning may damage or dissolve the
resistant and rust preventive material. This material is
protective rustproofing materials.
not undercoating. Undercoating is a tar-like, sound-
deadening material usually sprayed on the underside of
(7) When rust is found on equipment, the
a vehicle at time of manufacture. The word also applies
rusted area should be promptly treated to prevent
to the action of applying the tar-like material itself.
further corrosion. Sand or grind the rusted area until
Undercoating is sometimes used to refer to the
rust is removed from the metal. Then treat metal with
application of primer paints on metal bodies prior to
any of the metal conditioners and/or rust removers
painting the final coat. In neither instance is
described in paragraphs 2-19 through 2-28 of this TB, if
undercoating to be confused with rustproofing or
the surface will not be either painted or rustproofed
rustproofing materials.
immediately after cleaning. Spray cleaned metal with
primer and CARC paints and/or rustproof cleaned
(2) Rustproofing is not permanent. The materi-
metal, as appropriate.
al can be lost or destroyed. Tactical vehicles and trailers
treated with rustproofing materials should not be steam
{8) If possible, park trailers on a slope to allow
cleaned or cleaned with solvents. Such cleaning may
drainage of water from the trailer. If operating a dump
damage or dissolve the protective rustproofing
truck, tilt the dump bed before vehicle shutdown to
materials.
allow drainage of excess water.
(3) Rustproofing should never be applied over
(9) Vehicles with areas of Stage 1 or Stage 2
undercoating. In such instances, the material will be
rust should be cleaned of all existing rust. The cleaned
lost as the undercoating flakes and falls from the
area should also be treated immediately with any of the
underside of the vehicle.
metal conditioners and/or rust removers described in
(4) Army policy requires that all accessible
surface areas should then be primed and painted.
under surfaces to be rustproofed must be cleaned,
primed, and painted. This policy differs from
b. The following is a list of common misunderstand-
commercial practices. However, the additional barrier
ings regarding rustproofing materials, applications, and
of paint will provide greater protection to the metal.
techniques:
Section Il. OTHER TYPES OF CORROSION
2-8.
Galvanic Corrosion.
2-7.
General.
a. Whenever two different metals come in contact
a. Rust accounts for the majority of corrosion
with each other, a potential exists for the corrosive
damage on U.S. Army vehicles, but other types of
destruction of the atomically weaker of the two metals.
corrosion also limit the useful service life of equipment.
The further away these two metals are in terms of their
Notable among these additional types of corrosion are
atomic structure, the greater their potential for galvanic
galvanic corrosion, pitting, poultice, and the effect of
corrosion. Table 2-1 provides a list of common metal
the sun and ozone. These and other types of corrosion
and metal alloys. In this table, carbon is the hardest of
are discussed in this section.
metals and magnesium alloys are atomically the
weakest. The closer the different metals are to one
b. Two additional types of destructive factors are
another in this table, the less is the potential for galvanic
mildew and acid rain. While neither can be defined as
corrosion. The actual galvanic corrosive process is
forms of corrosion, they both contribute to corrosion.
similar to rusting to the degree that weaker metals
Both are destructive to Army equipment and,
become negative areas and lose electrons to the
therefore, fall within the objectives of the CPC
stronger positive atoms of the other metal.
Program. A better understanding of the causes and
b. The element carbon is included in the galvanic
prevention of these factors will also assist in
table of metals because this element is used to
accomplishing the overall goal of this technical bulletin.
2-8
