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 (3) Aluminum Surfaces. Aluminum should be cleaned by light abrasive blasting, power wire brushing,
or orbital sanding. Only stainless steel wire brushes, scouring pads, or aluminum oxide abrasive sanding
disks shall be used. None of these materials shall have been previously used on other metal, or for the
removal of copper-pigmented paint, prior to being used on aluminum.
(4) Surface Preparation of Coated Metal. Brush blasting may be used instead of blasting to bare
metal in those instances where an epoxy coating is in good condition and has been applied over a well-
prepared surface. This method should result in a surface retaining all paint films, but free from all rust,
scale, and foreign matter.
(5) Touchup painting. When only localized areas or spots requiring painting, it is essential that
removal of the old paint be carried back to an area of intact and adhering paint film. The edges of the
tightly adhering paint remaining around the area to be recoated shall be sanded to a smooth slope
(feathered) to allow proper blending and prevent laying new paint over loose or cracked paint. Areas of
intact paint to be over coated shall first be roughened. A tack coat shall then be applied prior to final
coating.
(6) Bilges and Sumps. Structures and fittings below floor plates in machinery spaces (bilges, bilge
wells, and sumps) may require special cleaning methods. Bilges on surface ships will be cleaned at
shipyards using the hand cleaning method (or equivalent) described in paragraph 3-22, Hand Cleaning of
Ships' Bilges.
(7) Wet Spaces. In wet spaces, remove corrosion products and cracked or loose paint by mechanical
means. Retain tightly adhering paint. Edges of paint film around the area to be recoated must be tapered
(feathered). Remove stains on old paint by solvent cleaning, detergent cleaning, or both. Rinse with clean
freshwater and dry before repainting. Apply primer to the bare metal areas so it overlaps the intact paint.
Apply topcoats over the spot-primed areas and the remaining intact painted surfaces. Intact painted areas
do not require priming.
d. Mixing Epoxy-Polyamide Coatings.
(1) Mixing ratios of epoxy coatings are 1:1 by volume; for example, 5 gallons of component 'A' mixed
together with 5 gallons of component 'B'.
(2) Mixing Procedures. Each individual component shall be thoroughly stirred prior to mixing the
components together. After mixing equal volumes of the two components, this mixture shall again be
thoroughly stirred until well blended. The induction or stand-in time shall be adhered to. Induction time is
defined as that time immediately following the mixing of components A and B during which the critical
chemical reaction period of these components is initiated. This reaction period is essential to ensure the
complete curing of the coating.
(3) Epoxy Primer Induction Times. The approximate temperature of the paint components in storage
should be estimated to judge the amount of induction time and the pot life that might be expected. The job
site application temperature will affect the time required for the paint to cure, and must be considered in
estimating induction time, cure time, and the effect of batch size on these functions.
(a) To ensure that the reaction proceeds uniformly, the paint should be stirred periodically during its
induction period. This action prevents localized overheating or hot spots within the paint mixture.
e. Epoxy-Polyamide Coating Application. Epoxy-polyamide coatings may be applied by brushing,
spraying, and rolling or dip coating. Application is described below.
(1) Thinning. Up to 1 pint of ethylene glycol monoethyl (EGM) ether for each gallon of mixed paint
may be added if the paint has thickened appreciably during cold temperature application, or when
necessary to improve application characteristics. When applied at the proper thickness, without thinning,
these paints have no tendency to sag.
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