Due to differences in microenvironments and corrosion products, it is necessary to consider at least four distinct stages in the history of marine iron artifacts. These stages are 1) initial immersion, 2) concreted with residual metal, 3) concreted with no residual metal, and 4) postexcavation. In the second and fourth stage, characterization of the corrosion products is complicated by their reactivity with the atmosphere, thus necessitating the use of specialized sampling and measurement techniques. The formation, occurrence and reactivity of sodium chloride, basic ferrous chloride, ferric oxyhydroxide and hydrocarbons in marine iron corrosion products are discussed. See also AATA 15-1703.