Solvents, Solvation, Solubilization and Solution: The solubility of materials. An introduction for conservators

„How does it work?“ This is the central question of the following educational article on the effect of solvents and the solubility of materials. In order to understand dissolution processes, it is essential to know the fundamentals of solvent properties and the materials to be dissolved. These build the theoretical framework to set up conceptual strategies in restoration practice. The thermodynamics are the basis for the presented concept. A parametrisation system is introduced as a working tool to visualise the correlation of different relevant values. The most decisive dimensionis the cavi tation energy, i.e. the cohesion energy of the liquid. This determines the entropy of the dissolution process and as such is the driving force in the process of mixing. The cavitation energy is the key dimension to describe the rate of dissolution. In conservation practise the rate of dissolution can, in principle, be controlled by manipulation of the vapour pressure of the solvent. Further aspects such as “leaching” upon short-term action of solvents on oil paint will be illuminated. The last part of the text delivers the tools and strategy on how to perform solubility tests on micro-samples in practice and how to derive a sound choice for a suitable solvent, based on the presented scheme.