Historically:
* Animal parts like hooves, bones, and hides were used to make gelatin, a protein-based substance used in adhesives. This process involved boiling these materials to extract collagen, which formed the basis for the glue.
Modernly:
* Most glues today are made from synthetic materials like polyvinyl acetate (PVA) or polyurethanes. These materials are more readily available, cheaper to produce, and often have better performance characteristics than traditional animal-based glues.
* While some specialized glues might still use gelatin for specific applications (like food-grade adhesives), the use of animal products in glue making is largely a thing of the past.
So, while horse hooves were once used in glue production, they are not a common ingredient in modern adhesives.