Page 662 - Corrosion Engineering Principles and Practice

616 C h a p t e r 1 4 P r o t e c t i v e C o a t i n g s 617

typically used as a postproduction treatment to provide cost-effective,
temporary corrosion protection and to control existing corrosion on
any metals. CPCs may be useful in providing supplementary
protection for paint systems that have deteriorated or become
damaged in service. They are applied as fluids by wiping, brushing,
spraying, or dipping. These compounds are usually immiscible with
water but may contain some water displacing components to remove
water from surfaces and crevices.
A number of these fluids are based on lanolin and contain
various solvents and inhibitors. The evaporation of the solvents
leaves either thin soft films, semihard films, or hard resin films that
provide varying degrees of short-term protection. There is a large
range of CPCs that are commercially available ranging from water
displacing to non-water displacing soft film and water displacing to
non-water displacing hard film. The exact compositions of CPCs are
not known due to their proprietary nature however information

(a)
FIGURE 14.6 Two steel washers exposed to a daily mist of water containing
3 percent sodium chloride (a) without CPC after two days and (b) with
a commercial CPC after fifty days.