Acrylic picture varnish for thin stained films.

The bright pigments of cave pictures in Spain have been preserved from Paeleolithic times by the accidental formation of a surface film of calcite (Kuhn, 1952), and since then many glazes have been used deliberately for the protection of colours. The idea of varnishing glass slides is not novel, but practical difficulties concerning preparation, pH, and especially viscosity, have discouraged its use. This paper describes the easy and successful application of modern synthetic resin varnish to preserve stained microscope slides for repeated examination. I