Pressboard is a special product based on the purest cellulose, extracted from long-fibered coniferous trees. These are formed into a non-woven material without using any additional binding agents and then pressed. The high chemical purity means pressboard is an extremely suitable insulation material for electrical machines (impregnated with resin), capacitors (impregnated with oil or resin) and particularly oil-filled transformers. The material properties allow classification in insulation class A (105° C) and are manufactured in accordance with the IEC standard.
Depending on the thickness of the material, a distinction is made between sheet and rolled press board.