Volvo VN Service Manual page 12

Group 18 Rustproofing Design and Function
Application
Rust is iron oxide (Fe O ). Rust forms in the presence of
2 3
water (H O) on an unprotected iron surface or where the
2
primer and top coat is damaged. Cavity wax works on
the principle that if air and moisture cannot reach the
material surface, there cannot be any oxidation of the
material. The liquid wax dries to a semisoft coating that
will slowly dry out. Depending on the manufacturer and
product, the drying period is typically between three to
five years.
The rustprotection applied when the cab was produced,
is adequate for normal use and service. If an extention
of the cab rustprotection is desired or if the vehicle is
used in a severe application, it is recommended that
cavity wax is re-applied every 3rd year.
The wax should flow easily when applied but not so easy
that it runs off without forming a good coat. Wax consis-
tency can be adjusted with mineral spirit if too thick. It
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should flow and spray easily. Retreatment or new appli-
cation should be to specification. However, since it is
hard to measure the thickness of the coat, apply enough
to cover the surface but not so much that it starts to run.
Run-off does not harm the finished result, however, it is
wasted material.
Application is typically done with an air gun and a flexi-

ble wand. The wand should have a 360 spray nozzle.
The wax is applied by inserting the flexible wand into a
profile and operating the air gun while slowly pulling the
wand out. Before application of the cavity wax, test the
spray pattern and coverage on a piece of cardboard. For
complete coverage, note the speed at which the wand is
moved. Try to simulate the same or slower application
speed when performing the application procedures. This
is especially important when treating areas (such as the
bottom rails) that can not be visually monitored during
the application.
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Before reapplication, the surface must be clean and dry.
If there are areas of rust, remove the rust and apply
primer before the wax is applied. Use Sherwin Williams
wash primer JBP 980 and allow it to dry thoroughly. Ap-
ply Sherwin Williams repair primer P6A47 and allow to
dry thoroughly.

The cab and wax should have a temperature of 18 C

(70 F) or above to get the right penetration into joints
and corners. If the surface must be cleaned before appli-
cation of wax, use water and let dry before applying the
wax.
In applications where rustprotection must be used in ar-
eas that are subject to abrasion (like wheel spray), there
are heavier rustprotection waxes available that are made
for exterior application.
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