Examination of Firearms Review: 2007 to 2010 - Interpol

6. Marine and Protective Coatings
In their article “Anticorrosive coatings: a review” Sorensen and coauthors provide
an excellent description of the utility and composition of anticorrosive coating
systems.[127] This reference is particularly helpful to the forensic paint examiner
because these types of coatings are not routinely encountered in case work. The
authors’ review includes approximately 350 references as well as comprehensive
descriptions and examples of the binders and pigments utilized in these coatings.
In addition, protective mechanisms of barrier, sacrificial, and inhibitive coatings
are described in detail.
In their research, Naderi and Attar evaluated the effectiveness of zinc aluminum
phosphate in comparison with zinc phosphate as an inhibitive pigment.[128]
Modification of the cationic constituent resulted in superior performance as
compared to zinc phosphate.
Silicone-organic resin systems, particularly silicone-epoxy resins, have
established a market segment in the protective coatings industry. Compared to
the industry standard of three- to four-coat 2K urethane systems, silicone-epoxy
hybrid technology offers reduction in VOCs, elimination of isocyanate health
effects, and improved durability against weathering, corrosion, and chemical
attack.[129;130]
Antifouling coatings are used to prevent organisms such as barnacles from
growing on a ship’s surfaces, which can increase fuel consumption by as much
as 40%. In addition to fuel savings, a reduction in millions of tons of CO2 and
SO2 emissions can also be realized.[131] Currently, cuprous oxide (Cu2O) is the
antifoulant most widely used. Organic biocides are also applied to supplement
the antifouling effect. As copper prices continue to rise, marine coatings
companies have launched a number of new products that are more
environmentally friendly and increase fuel efficiency. International Paint
introduced Intersleek ® 900, a biocide-free fluoropolymer foul release coating in
2007. They have since introduced a number of high volume solids (78-80%)
primers.[132] Hempel (Kongens Lyngby, Denmark) has introduced Hempasil X3
which uses hydrogel silicone to prevent fouling on a vessel’s hull.[133] The
water absorbent hydrogel forms a polymeric network over the surface such that
organisms perceive the hull as a liquid, not as a solid surface. As a result, the
organisms do not try to latch on.[134] Nippon Paint Marine Coatings, Co.
(Nagata-Ku, Japan) has developed a marine paint that contains a proprietary
polymer compound that turns to a gel when it comes into contact with water. The
resulting smooth surface causes a significant reduction in drag.[135]
Sherwin-Williams Industrial and Marine coatings has introduced SeaGuard 6200,
a high solids (80%) epoxy that is free of heavy metals.[131;134] Researchers in
Denmark are also evaluating the potential use of peroxides of magnesium,
131