Behaviour of moulding sands with hydrophilic binders in dry air

The work presents results of research on changes of elasticity and durability properties of moulding sands with a hydrophilic binder. The research concerns the surface layer of a mould. The presented loss of durability in the layer can be caused by too fast dehydration of the binder. The course and degree of changes depend on air temperature and moisture, grain size of the moulding sand, and amount of the binder. An ultrasonic method developed by the author allows observation of kinetics of the changes. Results obtained from the method have practical meaning for the mould technology.