Baking Pot Codex Restoration Project, Belize

Ground Layer Composition

The cream, white and brown grounds all contained significant quantities of various calcitic minerals, clay minerals and quartz, similar to those detected in the paints. Grain size of the component minerals, generally larger than the paints, varied with each type of ground, but all were less than 100µm (considered microcrystalline). "Cryptocrystalline calcite" was a significant component, as with the paint layers. In general, the rough cream and the smooth cream were the most homogenous and finely textured of all the ground types. The white ground with red flecks had less finely ground grains. The brown ground was the coarsest, least homogenous and crumbly. The red ground, found occasionally as an intermediate layer with the brown ground, contained hematite as a colorant, ground more coarsely than the same mineral used in the paint.

FTIR analysis detected no organic component within the ground layers that might indicate use of organic binders, such as have been found elsewhere [Magaloni et al. 1995b]. As with the paint layers, it is more likely that slaked lime functioned as a binder, cementing the ground particles. The clay minerals detected in the ground layers may have been part of the calcareous or pigment raw materials, or deliberately added later to modify certain properties of the mixture [Hansen 2000].

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