MIL-HDBK-1110
In some cases (e.g., with vinyl or chlorinated rubber coatings),
another generic type coating may have to be used, because the old
one is no longer permitted by many local environmental
regulations.
Before contracting any tower painting, it is necessary
to determine if any existing paint on the tower contains lead.
Lead may be present as one or more components of alkyd paints or
as pigmentation for the aviation orange color. Unless the
absence of lead is definitely known, samples should be taken and
submitted to a laboratory for analysis. Refer to NFGS-13283 or
CEGS 02090 for information on removal, containment, and disposal
of lead-containing paint. If the generic type of the existing
finish coat is not known, a compatible coating may be selected by
merely determining its solvent solubility. To do this, soak a
cloth in methyl ethyl ketone or acetone, rub it against the
existing paint, and visually check for pickup of paint. The
paint is classified as "solvent soluble" if paint is picked up,
and as "solvent insoluble" if not.
The common practice of applying paint by glove is not
recommended. It produces neither a continuous nor a uniformly
thick paint film. Roller application is also not recommended
because of difficulties in coating irregular surfaces. Spray
application by portable equipment produces the most attractive
finish but generally produces much overspray. Electrostatic
spraying can eliminate overspray, if it is available on high
platforms.
Spray cans can provide a quick cosmetic touch-up for
small damaged areas. Brushing is generally the most practical
application method to coat sharp edges, crevices, and corners.
It also can produce a relatively uniform, continuous film.
5.7.2.1
Towers With Only Cosmetic Coating Defects. Maintenance
painting to correct fading, discoloration, or limited intercoat
peeling should be undertaken when the existing aviation orange on
the upper portion of the tower fails to meet the requirement of
the color tolerance chart of the FAA (refer to Advisory Circular
70/7460-1G). Whatever the construction material, the only
surface preparation that is required is removal of loose
contaminants with a bristle brush or by washing. One or two
coats of acrylic latex finish (e.g., TT-E-2784), as required for
complete hiding of the existing paint, should be applied to the
cleaned surfaces. Normally, weathered exterior coatings are
sufficiently textured for good adhesion and general compatibility
of latex topcoats. However, severe chalking of the old coating
may present an adhesion problem for latex coatings.
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