There has been some debate among archaeologists about whether the dark blue-grey of Gunmetal Columbia Plain was an intentional attribute, or one that occurs as a post-depositional consequence on sherds submerged or buried in substances high in iron or manganese. Some cross-mended archaeological examples show that this latter situation does, indeed occur (see Columbia Plain Type Index Specimen # 2885), however the presence of Spanish museum examples with this kind of coloration (see Lister and Lister 1987:109), suggests that the gunmetal enamel also comprises an intentional variety of Columbia Plain.
Light cream to buff, occasionally pink, paste color, with a soft, chalky clay texture. Medium to dark grey or blue-grey tin enamel covering the vessel, produced by the addition of iron oxide or manganese to the tin glaze. Otherwise undecorated.