There are many varieties of paper; the classification methods are also inconsistent. There are three ways to classify habits. ① According to the production method, it is divided into handmade paper and machine-made paper. Handmade paper is mainly made by hand, using a curtain net frame and manually fishing it out one by one. It has a soft texture and strong water absorption, and is suitable for ink writing, painting and printing, such as Chinese rice paper. Its production accounts for a small proportion of the total production of modern paper. Machine-made paper refers to the general term for paper produced by mechanization, such as printing paper, packaging paper, etc. ② According to the thickness and weight of the paper, it is divided into paper and cardboard. There is no strict distinction between the two. Generally, those weighing less than 200g per square meter are called paper, and those weighing more than 200g are called cardboard. Cardboard accounts for about 40-50% of the total paper production and is mainly used for commodity packaging, such as box cardboard, packaging cardboard, etc. Internationally, paper and cardboard are usually counted separately. ③ Divided by use: newsprint, which is a special printing paper mainly used for news publication. Due to its large proportion, it is customary to be listed in a separate category; printing paper and writing paper, which are used for printing and writing and include painting and drawing. Paper; packaging paper; technical paper (industrial and agricultural technical paper); sanitary paper; processed base paper for further manufacturing and processing of paper; cardboard; processed paper, etc.
Paper is widely used, including industrial paper, packaging paper, household paper, and cultural paper. Cultural paper includes writing paper, art painting paper and printing paper. Printing paper is generally divided into five types: newsprint, letterpress paper, offset paper, coated paper and special paper.
Newsprint. Also called white newspaper. It has a soft texture, strong ink absorption, and a certain tensile strength, but has poor water resistance and is prone to yellowing and brittleness. Mainly prints newspapers and periodicals.
Letterpress paper. It is a special paper for letterpress printing. The texture is uniform, the color is white, slightly water-resistant, and not easy to turn yellow and become brittle. Mainly prints books and magazines.
Offset paper. It is a higher-grade printing paper. The texture is tight, the paper surface is smooth, the opacity and whiteness are high, and the water resistance is strong, making it suitable for lithographic printing. It mainly prints books, periodicals and covers, magazine inserts, pictorials, trademarks and labels, etc.
Coated paper. Also known as coated paper, it is a high-grade printing paper that is coated with a layer of white paint on the surface of the base paper and then calendered or super-calendered (the base paper is non-coated paper such as offset paper and letterpress paper). It has high surface smoothness, white color and strong water resistance. Suitable for printing higher-end picture albums, book inserts, calendars, greeting cards, etc. In recent years, Yuanguang coated paper has been widely used in printing. Matt coated paper is made by lowering the gloss and processing it into coated paper with a smooth surface. Albums and magazines printed with it often give people an elegant feeling. It is most suitable for long-term reading because there is no stimulation from high light, so the eyes will not feel tired. Print prints with ornamental value.
Specialty paper. Refers to paper that has certain special functions and is suitable for special uses. Some of them are made by applying chemical reagents to the slurry and then processed, and some are made by secondary processing of the original paper.
The appearance of special paper is significantly different from that of commonly used coated paper and offset paper. Most papers have stripes or patterns on the surface. Some papers are very smooth, and some papers have excellent transparency. There are also paper surfaces that show fluffy color changes. Usually used to print business cards, invitations, exquisite greeting cards, menus for restaurants and hotels, etc. Its prints are rich, luxurious and sophisticated.
In recent years, with the rapid development of the chemical industry, the use of synthetic paper in printing has continued to increase. The so-called synthetic paper is a paper made of synthetic polymer substances as the main raw material, which is processed to give the paper printing properties and is used for printing. It has the characteristics of light weight, folding resistance, wear resistance and moisture resistance. The manufacture of synthetic paper does not require natural fibers and is conducive to environmental protection. It is a promising printing paper.