Bonding varnishes EB 548 and Remisol EB 549 are used for dry adhesive bonding of electrical steel sheets. Coated sheets or stampings are bonded under heat and pressure. Thus, riveting or welding of the magnetic cores is not necessary and core losses are reduced. The bonded stacks provide optimum thermal conductivity and prevent frequency humming. They do not breathe under temperature changes which prevents interlaminar corrosion. At the same time, they ensure that the steel laminations are insulated.