Electrical insulation paper

Pressboard, a board made by compressing layers of paper together and drying them, has been used for installation purposes in many of the first electrical machines.

In the late 1920s, Hans Tschudi-Faude became the director of H. Weidmann Limited and began developing a type of pressboard that would meet the higher standards needed for the newer, more powerful transformers.

Unlike older methods of pressboard production, Transformerboard was not based on used paper or cotton waste but was made with high-grade sulfate cellulose.

The new product was made purely out of cellulose without a resin or binder, improving electrical insulation capabilities and could be completely dried, degassed, and oil impregnated.

Electrical insulation papers are made from well delignified unbleached kraft pulp.

The wet sheets are hot- or cold-press dried and finished on separate machines.