How to Refinish Wood siding with Latex Paints by smithhaleey

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									                    U.S. DEPARTMENT OF AGRICULTURE • FOREST SERVICE
                    FOREST PRODUCTS LABORATORY • MADISON, WIS.
                    In Cooperation with the University of Wisconsin




                    U.S.D.A. FOREST SERVICE
                    RESEARCH NOTE
                    FPL - 0232
                    1976


                         HOW TO REFINISH WOOD SIDING
                              WITH LATEX PAINTS
                                             By
                                EDWARD A. MRAZ, Technician
                          Forest Products Laboratory,1 Forest Service
                                U.S. Department of Agriculture


                                                         SUMMARY
    Every homeowner with painted wood                                 face will form a satisfactory bond with latex
siding and trim at some time faces the job of                         paints, and suggestions are given on prepar-
repainting. In this Note a simple test is                             ing the surface to achieve a satisfactory bond.
described to determine whether an old sur-



                                                     INTRODUCTION
     Weathering is the action of sun, wind,                           be prevented before repainting. This water
rain, dew, snow, hail, and dust. On painted                           or moisture in walls could be from inade-
wood siding and trim, weathering gradually                            quate vapor barriers, ice dams, leaky roofs,
causes the best quality paint to wear away,                           and poor gutters and downspouts.
and the siding must be repainted. Repainting                               Repainting should be considered only
is a major job for the homeowner. Thus, it                            after previous paint has weathered so that
is worthwhile to learn how to extend intervals                        it no longer covers and protects the wood.
between paintings.                                                    Repainting too frequently can lead to a too
     The purpose of this Note is to outline the                       thick paint film that causes paint failure.
procedures to follow to attain a durable paint
surface on wood siding. However, if water or                          Maintained at Madison, Wis., in cooperation with the
moisture is getting behind siding, this must                             University of Wisconsin.




                                                                -1-
                                PREPARATION OF SURFACE
     The following six steps should be help-           surfaces.) Rinse old paint thoroughly with
ful in preparing for repainting.                       water from a garden hose.
     (1) Scrape off all loose paint.                       (4) Brush all exposed wood and joints
      (2) Sand bare spots and feather the              with a water-repellent preservative.
edges of surrounding paint.                                (5) After 2 or 3 days of sunny, dry
     (3) Remove chalk from old paint with              weather, apply an oil-base primer paint to
steel wool or with sponge and detergent                bare spots to completely obscure the gram.
solution. (A chalk-free surface ensures a good             (6) Calk all open joints and cracks with
bond between old and newly applied paint               a synthetic calking compound.




                                     TEST FOR CHALKING
    A simple, helpful test has been devised            onto the dry, freshly painted surface. With-
to determine if a surface of old paint film is         draw it quickly.
free of chalk and suitable for repainting. A               If the tape is free of paint, the latex
small area of old paint surface is coated with         paint is well bonded to the old surface, and
latex paint, and the paint allowed to dry 24           repainting can be started.
hours or more.                                             If the new latex paint adheres to the
    To test for adhesion, firmly press one             tape, this indicates the old surface is still
end of an adhesive type of tape about 2-3/4            too chalky. If this is the situation, an oil-base
inches long by 1 inch wide (like that used             primer coat should be applied.
with a gauze pad for covering minor wounds)



                                    APPLICATION OF PAINT
     After the old paint surface has been              paint is applied on hot, dry, windy days in
prepared satisfactorily, apply two coats–ac-           direct sunlight, dampen the area about to be
cording to directions given by the paint               painted by using a water-soaked sponge. This
manufacturer. Avoid painting late in the               will improve paint spreadability, and the latex
evening–about 2 hours before sunset. Heavy             paint will not dry too quickly.
dews are likely to form and cause water-                     Finally, always use a high-quality ex-
marks on the paint.                                    terior latex paint; quality iS usually related
    Avoid painting if temperature is likely            to price.
to fall below 50°F during the night. If latex




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