Structural adhesives fall into four main categories according to whether they set because of change in temperature alone; Change of temperature accompanied by loss of solvent; Loss of solvent alone; Or chemical reaction. The author discusses the chemical and physical factors influencing adhesion and describes individual synthetic resins in the thermoplastic and thermosetting groups. Consolidants are used to restore mechanical stability to fragile objects. Those described are wax (synthetic and natural), polyesters, ethoxyline (epoxide) resins (e. G. Araldite), and polyethylene glycol synthetic waxes.