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 a. Before using, rinse brushes with paint thinner. Brushes that are to be reused the following day need
to be marked for white light colors, or dark colors. Brushes should be suspended by the handle in a
closed container, with the bristles immersed in paint thinner or linseed oil to just below the bottom ferrule.
The weight of the brush should not rest upon the bristles.
b. Brushes that are not to be reused immediately shall be cleaned with thinner or some other solvent (at
least three cleanings), and then washed with detergent and water. Brushes shall be stored suspended
from racks by the handle or wrapped in paper and stored in a flat position.
4-4. Paint Rollers. The selection of a paint roller for a job depends upon the type of paint being used and
the surface to be coated.
a. Roller Description. A paint roller is a cylindrical sleeve or cover, which slips onto a rotatable cage.
The inside diameter of the cover is 1 1/2 to 2 1/4 inches. In length, covers are 3, 4, 7 and 9 inches.
Special rollers are available in lengths from 1 1/2 to 18 inches.
b. Types of Roller Covers. Proper paint application depends upon the selection of a cover with the
desired fabric and fabric thickness (nap length). Selection is based on the type of paint to be used and the
smoothness or roughness of the surface to be painted. The fabrics used in roller covers are:
(1) Lambs Wool (Pelt) is the most solvent-resistant type of material used and is available in nap
length up to 1 1/4 inches. Lambs wool is recommended for application on semi-smooth and rough
surfaces; it mats badly in water and is not recommended for water-base paints.
(2) Mohair is made primarily of angora hair. It is solvent-resistant and is supplied in 3/16 to 1/4-inch
nap lengths. Mohair is recommended for synthetic enamels and for use on smooth surfaces, and can be
used with water-base paints.
(3) Dynel is modified acrylic fiber which has excellent resistant to water. It is best for application of
conventional water-base paints and solvent-base paints, except those, which contain strong solvents
such as ketones. Dynel is available in a range of nap lengths from 1/4 to 1 1/4 inches.
(4) Dacron is a synthetic fiber, which is somewhat softer than Dynel. It is best suited for exterior oil or
latex paints. Dacron is available in nap lengths ranging from 5/16 to 1/2-inch.
(5) Rayon roller covers are not recommended. Rayon mats badly in water and generally produces
poor coating results.
4-5. Paint Thickness Gages. Paint thickness is measured in terms of wet film thickness (WFT) and dry
film thickness (DFT). The WFT measurements are useful in monitoring on site paint applications. The
DFT measurements determine the final barrier film obtained for preservation. The gages used for the
measurements of WFT and DFT are described below.
a. Minimum Film Thickness Requirements: When a measurement of paint thickness is specified, a
minimum of five DFT measurements shall be recorded for every 1,000 square feet of painted surface. The
average of these readings shall be the official recorded value.
b. Wet Measurements. WFT gages are used to check freshly applied coatings. The WFT multiplied by
the decimal equivalent of the percentage of solids by volume gives an estimate of the DFT, which will
remain after the solvent has evaporated. Wet film gages to be used are described below.
(1) Interchemical WFT Gage. The interchemical WFT consists of an eccentric center wheel attached
to two concentric running wheels. Rolling of the gage results in the central measuring wheel dipping into
the coating. The point at which the film touches the center wheel measures the thickness of the film,
which can be read on the mil scale provided on one of the running wheels. The range of the particular
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