To detect art forgeries, a scientific laboratory has four possibilities. Analysis of the material checks if it is of a type which was known at the alleged time of origin. Technological studies reveal if historic or recent techniques of manufacture have been used. Signs of aging, like a patina, sinter crusts, or the development of a craquelé, which scarcely can be imitated convincingly, provide indications of authenticity. Finally, the techniques of dating with physical and chemical methods provide further possibilities for authentication of works of art. -- AATA