MIL-HDBK-1011/1
exterior coating and vapor barrier enters the air conditioned space and does
not remain trapped within the insulation and wall material. Use vinyl wall
covering in air conditioned buildings when a vapor barrier is installed as
recommended in Section 7.
Substrate Preparation. In the tropics water infiltration and
9.8.3
mildew growth are both problems where concrete masonry units are used,
include explicit instructions for surface preparation for both new and
existing concrete and masonry surfaces.
On new masonry surfaces, specify a latex block filler. The filler
coat must be thoroughly brushed in, otherwise leaking will occur. Two finish
coats of acrylic emulsion paint with mildewcide is recommended for both
masonry and concrete surfaces.
In tropical areas, take care to assure that wood, concrete and
masonry surfaces are dry before painting. Latex paints may be more tolerant
of damp surfaces but they are also slow drying where the humidity is high.
Efflorescence (white to gray powdery products) may occur on concrete surfaces,
especially on interior walls of air conditioned buildings. Include the
appropriate requirements for efflorescence removal. Where moisture migration
through concrete or masonry walls from the outside to the inside presents a
problem, seal the outside with a surface conditioner or concrete primer to
correct the problem. If interior concrete walls are continuously damp, cracks
in roofs that allow the entrance of rainwater must be suspected. Repair these
and cracks around the windows before painting. Do not paint interior steel
that will be fireproofed.
9.8.4
Repainting.
Localized repairs to a coated surface are ordinarily
best made by cleaning exposed substrate, spot priming and topcoating with the
same type of material existing on the surface. Topcoating of a weathered
paint is generally done with a similar type of topcoat. In tropical areas,
paints must be mildew-resistant. Microorganisms may utilize the oils in
oleoresinous or alkyd paints as a source of food. Dirt, pollen or other
surface contamination may also accelerate the growth of microorganisms.
Softgel coatings and textured coatings permit more rapid pick-up of mildew.
Thus, it is desirable to obtain hard, smooth, inert paint films and keep them
free of contamination. Because of the high temperatures and rainfalls in
tropical areas, store all materials indoors, out of direct sunlight. Procure
no more paint at one time than can be used in one year.
In topcoating weathered paint, remove all mildew, dirt, grease,
chalk or other contaminants that might deter good bonding along with loose
paint. Dirt, mildew and other airborne contaminants collect rapidly in
protected areas such as under the overhangs of roofs; remove them by
appropriate cleaning prior to repainting.
46
Previous Page
