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Class I: Exterior Surface Conditions Generally Requiring No Paint
|beyond maintenance/painting: repair and replacement
detergent (non-ammoniated) + bleach + TSP (phosphate-free)
Dirt, Soot, Pollution, Cobwebs, Insect Cocoons, etc.
Cause of Condition
Environmental "grime" or organic matter that tends
to cling to painted exterior surfaces and, in particular,
protected surfaces such as eaves, do not constitute a paint
problem unless painted over rather than removed prior to repainting.
If not removed, the surface deposits can be a barrier to proper
adhesion and cause peeling.
Most surface matter can be loosened by a strong, direct
stream of water from the nozzle of a garden hose. Stubborn
dirt and soot will need to be scrubbed off using l/2 cup of
household detergent in a gallon of water with a medium
soft bristle brush. The cleaned surface should then be rinsed
thoroughly, and permitted to dry before further inspection
to determine if repainting is necessary. Quite often, cleaning
provides a satisfactory enough result to postpone repainting.
| moist, mildered areas
bleach test fro mildew
one cup non-ammoniated detergent, one quart household
bleach, and one gallon water, bristle brush (photo of ingredients)
Cause of Condition
Mildew is caused by fungi feeding on nutrients contained
in the paint film or on dirt adhering to any surface. Because
moisture is the single most important factor in its
growth, mildew tends to thrive in areas where dampness
and lack of sunshine are problems such as window sills, under
eaves, around gutters and downspouts, on the north side of
buildings, or in shaded areas near shrubbery. It may sometimes
be difficult to distinguish mildew from dirt, but there is
a simple test to differentiate: if a drop of household
bleach is placed on the suspected surface, mildew will
immediately turn white whereas dirt will continue to look
Because mildew can only exist in shady, warm, moist areas,
attention should be given to altering the environment that
is conducive to fungal growth. The area in question may be
shaded by trees which need to be pruned back to allow sunlight
to strike the building; or may lack rain gutters or proper
drainage at the base of the building. If the shady or moist
conditions can be altered, the mildew is less likely to reappear.
A recommend solution for removing mildew consists of one
cup non-ammoniated detergent, one quart household bleach,
and one gallon water. When the surface is scrubbed with
this solution using a medium soft brush, the mildew should
disappear; however, for particularly stubborn spots, an additional
quart of bleach may be added. After the area is mildew-free,
it should then be rinsed with a direct stream of water from
the nozzle of a garden hose, and permitted to dry thoroughly.
When repainting, specially formulated "mildew-resistant"
primer and finish coats should be used.
Cause of Condition
Chalking or powdering of the paint surface
is caused by the gradual disintegration of the resin in the
paint film. (The amount of chalking is determined both by
the formulation of the paint and the amount of ultraviolet
light to which the paint is exposed.) In moderation, chalking
is the ideal way for a paint to "age," because the
chalk, when rinsed by rainwater, carries discoloration and
dirt away with it and thus provides an ideal surface for repainting.
In excess, however, it is not desirable because the chalk
can wash down onto a surface of a different color beneath
the painted area and cause streaking as well as rapid disintegration
of the paint film itself. Also, if a paint contains too much
pigment for the amount of binder (as the old white lead carbonate/oil
paints often did), excessive chalking can result.
The chalk should be cleaned off with a solution of l/2
cup household detergent to one gallon water, using a medium
soft bristle brush. After scrubbing to remove the chalk,
the surface should be rinsed with a direct stream of water
from the nozzle of a garden hose, allowed to dry thoroughly,
(but not long enough for the chalking process to recur) and
repainted, using a non-chalking paint.
| rust-inhibitive primer
countersunk, spot primed, and the holes filled with
a high quality wood filler
denatured alcohol and water
stainblocking primer (Kilz)
Cause of Condition
Staining of paint coatings usually results from excess moisture
reacting with materials within the wood substrate. There are
two common types of staining, neither of which requires paint
removal. The most prevalent type of stain is due to the oxidation
or rusting of iron nails or metal (iron, steel, or copper)
anchorage devices. A second type of stain is caused by a chemical
reaction between moisture and natural extractives in certain
woods (red cedar or redwood) which results in a surface deposit
of colored matter. This is most apt to occur in new replacement
wood within the first ten to 15 years.
In both cases, the source of the stain should first be located
and the moisture problem corrected.
When stains are caused by rusting of the heads of nails
used to attach shingles or siding to an exterior wall or by
rusting or oxidizing iron, steel, or copper anchorage devices
adjacent to a painted surface, the metal objects themselves
should be hand sanded and coated with a rust-inhibitive
primer followed by two finish coats. (Exposed nail heads
should ideally be countersunk, spot primed, and the holes
filled with a high-quality wood filler except where exposure
of the nail head was part of the original construction system
or the wood is too fragile to withstand the countersinking
Discoloration due to color extractives in replacement wood
can usually be cleaned with a solution of equal parts denatured
alcohol and water. After the affected area has been rinsed
and permitted to dry, a "stainblocking primer"
especially developed for preventing this type of stain should
be applied (two primer coats are recommended for severe cases
of bleeding prior to the finish coat). Each primer coat should
be allowed to dry at least 48 hours.