MIL-HDBK-1110
Even a second coat of paint may leave the total coating system
with thin and uneven areas that may lead to premature failure.
Brushes are made with either natural or synthetic
bristles. A drawing of a typical paint brush is shown in Figure
8. Chinese hog bristles represent the finest of the natural
bristles because of their durability and resiliency. Hog
bristles are also naturally "flagged" or split at the ends. This
permits more paint to be carried on the brush and leaves finer
brush marks on the applied coating. Horsehair bristles are used
in cheaper brushes but are an unsatisfactory substitute for hog
hair. Nylon and polyester are used in synthetic bristles or
filaments. The ends are flagged by splitting the filament tips.
Synthetic bristles absorb less water than natural bristles and
are preferred for applying latex paints. However, synthetic
bristles may be softened by strong solvents in some paints.
Thus, natural bristles are preferred for application of paints
with strong solvents.
Brushes are available in many types, sizes, and
qualities to meet the needs for different substrates. These
types include wall, sash and trim (may be chisel or slash-
shaped), and enamel (bristles are shorter). It is important to
use high quality brushes and keep them clean. Brushes with
horsehair or with filaments that are not flagged should be
avoided. The brush should be tapered from side to center (see
Figure 8).
7.5.2.1
Procedure for Brush Application
a) Shake loose any unattached brush bristles by
spinning the brush between the palms of the hand and remove the
loose bristles.
b) Dip the brush to cover one-half of the bristle
length with paint. Remove excess paint on the brush by gently
tapping it against the side of the can.
c) Hold the brush at an angle of about 75 degrees to
the surface. Make several light strokes to transfer the paint to
the surface. Spread the paint evenly and uniformly. Do not
press down hard but use a light touch to minimize brush marks.
If there is time before the paint sets up, cross-brush lightly to
eliminate excessive brush marks.
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