MIL-HDBK-1110
Repair of exterior coatings may not be warranted with
the first appearance of weathering, but deterioration should not
proceed to the point that damage occurs to the substrate, or more
costly surface preparation or application techniques become
necessary. If lead-containing paint is present, the costs for
paint repair or removal will be much more expensive. If the
paint can be maintained in place, a great deal of savings will
result. New restrictions on abrasive blasting and other surface
preparation techniques may also significantly increase total
costs. Thus, scheduling of repairs should be made to avoid such
costly operations.
12.2.4
Plan for Maintenance Painting. The plan for
maintenance painting includes selection of the surface
preparation, application, and inspection methods and the
materials to be used.
12.2.4.1 Selecting Materials for Maintenance Painting. For
localized repairs to an otherwise sound coating system (12.2.3
types "b" and "c"), it is wise to repair a damaged coating system
with the same coating previously used or one of the same generic
type or curing mechanism to avoid incompatibility. If in doubt
as to the compatibility of a paint to be applied to an existing
finish, apply a small patch to it and inspect it after 2 to 3
days for any bleeding, disbanding, or other sign of
incompatibility.
For total recoating (12.2.3 type "d"), select the
coating as described for new work in Section 4 or 5.
12.2.4.2 Surface Preparation for Maintenance Painting. For
making localized repairs, it is best to use the surface
preparation methods for different substrates described in Section
6. It may be more practical or necessary, however, to use hand
or power tools rather than abrasive blasting where the amount of
work to be done is small, or where abrasive blasting would
contaminate an area.
Loose and peeling coating should be removed, and the
adjacent intact coating should be sanded to produce a feathered
edge and roughened paint surface extending 2 inches beyond the
repair area. The feathered edge will produce a smoother
transition between the old and new paint and roughening the
adjacent intact paint will permit good adhesion of the new
primer.
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