Using natural sulfite chemical wood pulp or cotton pulp, it is beaten and sizing without filler (material), and is made on a Fourdrinier paper machine. The base paper is impregnated with a swelling agent (concentrated zinc chloride solution or copper ammonium solution) to swell and gelatinize the cellulose. It is then bonded layer by layer on the gelling machine, and then aged and matured, water-immersed, desalted, and dried to shape it. Into steel paper. Usually red or gray is added. It is used in the electromechanical, textile and other industries to make various tool gaskets, insulation materials and other parts.

Steel paper is a special paper treated with a special process and is often used as insulation and heat-insulating materials.

Steel paper is made of cellulose and its derivatives. It uses a metal salt-zinc chloride solution that has strong swelling and gelling properties for cellulose as a treatment agent. Modified processed paper made by processing and laminating is also called hardened paper. Cellulose and its derivatives are chemicals. Sheets made from chemicals must be classified as plastics in Chapter 39. Please refer to the article provisions of this chapter. Non-foam plastic boards, sheets, films, foils and flat strips are classified into heading 3920. Check the subheadings under this heading and classify them into code 39207900 according to the specific name (original text is 39207200, this article is in the 2011 Customs Code does not exist in the manual).