Method to retard moisture absorption in pressboard structures

This paper discusses a technique for retarding moisture absorption by pressboard cylinders, used as winding tubes for transformer coils. The PARA-SEAL process involves treating the pressboard cylinders with paraffin wax. Since moisture absorption is markedly reduced, the cylinders do not grow and, therefore, maintain their as manufactured dimensions. The cylinders can then be used to wind transformer coils as received without redrying. This saves both process time and the associated costs since the cylinders can go directly to the coil winding machine from the receiving floor (outside vendor) or tube manufacturing section (in-house production). This benefit is especially favored with the 'just in time' concept of manufacture.