Sacrificial crust (croûte sacrificielle)
Thick multi-layered encrustation of organic libation residues — millet-beer, blood, fats — built up over generations of ritual use on Tellem and Dogon votive figures.
The sacrificial crust, known in French specialist literature as croûte sacrificielle, is the accretive surface deposit formed by repeated ritual libations poured over a wooden figure during active ceremonial use. On Tellem and early Dogon cliff-cave objects, the crust is typically composed of layered millet-beer residues, blood, vegetable matter, and fatty substances, consolidated over centuries into a hard, granular, dark-brown to near-black matrix that can be several millimetres thick and can entirely obscure the underlying carved forms. The crust is not merely a patina but a physical record of the object's ritual biography; its removal is irreversible and destroys primary evidence of use-life.
The crust is also the principal target of market forgery. Artificially induced crusts, created through accelerated libation application, burial in organic material, and heat treatment, can be visually convincing but differ from genuine crusts in their integration with the wood substrate. Authentic centuries-old crust penetrates micro-cracks and surface pores, shows differential density across layers that reflect intervals of heavy and light use, and is fused to the wood at a level detectable under magnification. Thermoluminescence analysis of crust-embedded organic material, combined with assessment of wood shrinkage and crack patterns consistent with long-term desiccation, provides the most reliable physical basis for distinguishing genuine from artificial accretions.