MIL-HDBK-1110
pass should overlap the previous one by 50 percent. Proper
techniques should also be used for brushing, rolling, or other
application procedures. Refer to Section 6. Special safety
requirements for paint application are described in Section 13.
9.6.8.2
Ventilation. The ventilation of tanks and other
enclosed areas where paint is to be applied and cured must meet
the requirements of OSHA's Confined Space Regulation, and the
contractor's safety plan required by contract specification.
Good ventilation is also necessary for proper coating cure.
9.6.8.3
Mixing/Thinning. Paints must be properly mixed as
described in Section 7. Paint solids often settle out during
storage and must be completely blended into the paint vehicle,
resulting in homogeneous mixture. For multi-component paints,
the inspector should ensure that all components have been mixed
in the proper proportion, that the mixing is thorough and that
the resulting paint is uniform in appearance. Required induction
times must also be met to obtain satisfactory application and
film properties. Although the paint manufacturer prepares paint
to produce a consistency for brushing, rolling, or spraying,
sometimes additional thinning is permitted in the specification.
Thinning of the paint must follow manufacturer's instructions for
both type and amount of solvent. A thinned paint will cover more
surface area but the dry film thickness will be less and may not
meet the requirements of the specification.
9.6.8.4
Film Thickness. Contract specifications may require a
minimum and/or a maximum dry film thickness for each coating
application. Wet film thickness measurements made at the time of
paint application are used to estimate dry film thickness so that
appropriate adjustments in the application procedure can be made
to meet the specification. Wet film thicknesses are not used in
meeting contract requirements because of the many factors
(solvent evaporation, wetting energies) that affect the
measurement. Procedures for making wet film thickness are
described in ASTM D 4414, Wet Film Thickness by Notch Gages and
in Section 10. The dry film thickness is estimated from the wet
film thickness according to:
Dry Film Thickness = Wet Film Thickness x Percent Volume Solids
100
The percent volume solids is available from the coating
manufacturer's data and should be part of the inspector's
records. Dry film measurements are made after the coating has
hardened. For steel surfaces, thickness measurements can be made
according to SSPC PA 2 or ASTM D 1186 or ASTM D 1400,
Nondestructive Measurement of Dry Film Thickness of Nonconductive
Coatings Applied to a Nonferrous Metal Base. (There are some
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