(3) Pour the vehicle into the pigment in small quantities; never add the pigment to the
vehicle. Stir each quantity thoroughly before more vehicle is added. Use 10 percent in the first
addition, 10 percent in the second, 20 percent in the third, and then add the remaining amount to the
pigment. Stir thoroughly to ensure the complete wetting of the pigment.
(4) Box the material by pouring it from one container to the other several times.
(5) Strain the material through double- or triple-thickness cheesecloth to ensure that no
(6) Stir the material occasionally during application. Stirring should be moderate and only
enough to keep the pigment in suspension. Too much agitation may cause darkening and the loss of
leafing power. Prolonged storage of mixed aluminum-coating materials may also destroy leafing power,
so carefully estimate the quantity to prepare.
PART C: PREPARING THE SURFACE
2-9. Surface Preparation. Good surface preparation is essential. Different surfaces, such as a nail
hole in wood trim or cracks in a plaster wall, require different treatment and materials. Several materials
are available to improve the surface before painting. They are undercoat, sealer, primer, size, wood
filler, plastic wood, caulking compound, putty, texture paint, spackling compound, joint cement, and
paint and varnish remover.
a. Undercoat. An undercoat is the coat applied prior to the finishing or the final coat. On old
work, the undercoat is the first coat applied; on new work, the undercoat is applied after the primer and
before the final coat. Undercoat is essential for its hiding power, and it provides a smooth surface for
the final coat.
b. Sealer. A sealer fills the pores of absorbent surfaces in preparation for painting. By
preventing the absorption of oil from the paint, a sealer reduces the number of coats of paint required
and ensures a stronger film. Some sealers are used to protect the final coat from chemicals that are
present in the surface. Sealers are usually applied as the first coat. There are many commercial sealers.
One type that you can easily make is a mixture of shellac and alcohol. Reduce the shellac with alcohol,
4 to 1 if it is to be used over a filler and 7 to 1 if it is to be used over stain. Then, pour the mixture into
an equal amount of lacquer to make a sealer.
c. Primer. A primer is a film-forming material used as the first coat of paint. It provides
adhesion for the following coats and prevents undesirable chemical reaction to the surface. It may be a
thinned first coat of paint or a specially prepared product. Different types of primers are available for
different types of surfaces. Exterior wood primer, epoxy primer, phenolic-resin primer-sealer, wash
primer, zinc-chromate primer, and metal primer are discussed below:
(1) Exterior wood primer. A wood primer is usually a thinned coat of the paint to be used or
a specially prepared coat.