Gelatin, a natural binder derived from animal protein, has been used as an adhesive long before the introduction of modern materials. Largely replaced by synthetic adhesives, gelatin conservation treatments have attracted new attention in response to the need for identifying more technically and culturally compatible materials for the stabilization of detaching, delaminating and blistering earthen finishes at Mesa Verde National Park (USA). The dry, protected climate of these ancient alcove sites allows re-consideration of the use of gelatin as an adhesive for the reattachment of earthen finishes with the added benefits of re-treatability, non-toxicity, versatility in viscosity and rheology, and low cost. Gelatin’s susceptibility to bio-deterioration and brittleness has prompted its substitution with synthetic adhesives, especially for easel and panel painting; however, these properties alone are not necessarily detrimental on earthen materials and can be controlled if understood. In order to advance the re-consideration of gelatin as a viable adhesive for earthen materials, laboratory testing and field evaluation over a ten year period are presented with a focus on critical properties related to its conservation use on earthen finishes.