Bone Glue — Frequently Asked Questions

Because reversibility is the requirement, not strength. Modern synthetic adhesives make joints stronger than the surrounding wood, so opening one destroys the material. An animal glue joint can be softened with heat and moisture, taken apart cleanly, washed off and reglued. That is exactly what furniture restoration and instrument repair need.

By degree of hydrolysis and therefore by grade. Both are collagen-derived, but bone glue is hydrolysed further, giving lower molecular weight, lower gel strength and a darker amber to brown colour. Gelatine is produced to food and pharmaceutical purity; bone glue is a technical product where colour and odour matter far less.

Because its controlled brittleness lets the wheel work correctly. A grinding wheel must release worn abrasive grit so fresh sharp grit is exposed, and that depends on the bond breaking down at a controlled rate under load. A bond that never released would glaze over and stop cutting.

By soaking in cold water until the granules swell, then warming in a water bath to around 60 degrees Celsius to dissolve. It should not be boiled, since excessive heat degrades the protein and weakens the joint, and it should be kept warm in use because it gels as it cools. It is also susceptible to microbial spoilage once made up.