What type of glue is made from animal hides, is water-soluble, and can be reactivated by adding water?

Hide glue is made from the collagen found in animal hides, and its unique properties make it a traditional choice in woodworking and cabinetry. Being water-soluble means that it can be easily cleaned up with water when still wet, and it allows for adjustments or repairs by simply reactivating the glue with moisture. This characteristic is particularly beneficial when working on intricate or fine wood projects, allowing for parts to be repositioned if necessary before the glue sets completely.

The other adhesives listed, such as PVA glue, are synthetic and do not offer the same reactivation feature, while contact glue and epoxy provide different bonding methods suitable for various applications but lack the water solubility and reactivation property of hide glue. Overall, hide glue is valued for its ease of use, historical significance, and suitability in fine woodworking applications.