Do you know the basic technical parameters of a sheet of paper?

If you are familiar with words like opacity, grammage or grain direction you probably know the basic parameters of paper. In the following lines, we will explain the differences between types of paper sheets. It will help you choose the best material for you printing.

Weight of paper

One of the most important parameters is the weight, also called grammage. It defines the weight of paper per square meter (g/m²). Grammage has an impact on the physical properties of paper as well as on the quality of final printing. It means – the higher the grammage of the paper, the sturdier and thicker the paper. Papers with the lowest grammage (30 to 60 g/m²) are used for newspapers and package inserts, grammage of 70 to 90 g/m² is used for printing direct mails and office materials. Paper with grammage of 90 to 120 g/m² is used for presentations and inside pages of magazines, 120 to 170 g/m² is suitable for books and publications whereas grammage of 170 to 250 g/m² is used for magazine covers or representational materials. Cardboards have grammage of 250 g/m² and are used for the production of business cards, boxes and announcements.

Thickness of paper

Grammage often relates to the thickness of paper. It stands to no reason that higher grammage means higher thickness. It is true in many cases, but there are some exceptions. These are for example papers for printing books especially when a publication with lower number of pages should reach certain thickness and keep low weight at the same time. They are called voluminous papers.

Opacity of paper

When we use paper with low grammage for a magazine, the text printed on the opposite side of the page may have a destructive effect on the reader. To avoid this, we should pay attention to the opacity of the paper. Opacity is a property of paper, which refers to the amount of light which is transmitted through it. Usually, it is directly proportional to the grammage of the paper.

Size of sheets

From the point of view of printing, the size of sheets is very important. The paper measurements are defined by ISO 216 standard. There are three groups of sheets, A, B, C. Each group refers to a series derived from the basic format. For example, A0 (841x1189mm) is followed by smaller formats A1, A2, A3, A4, A5 which we get when folding the longer side of the previous format.

Grain direction

Grain direction is an important parameter for the further book-binding processes. When the grain is parallel with the longer side of the sheet, it is called short grain. A long grain is when the grain runs across the long end of the sheet, i.e., is parallel with the shorter side of the sheet. The grain of the paper determines how the paper reacts to folding or binding. When choosing a wrong grain, it may result in binding problems and printing defects.

Whiteness and brightness of the paper

Whiteness and brightness of the paper are the most important visual properties of paper. The unit of whiteness is CIE. Whiteness measures the reflection of wavelengths of light across the visible spectrum. The higher level of whiteness can be reached by grain whitening using calcium oxide-based fillers or by adding optical brighteners. Whiteness affects the whole visual of the print. Paper with high whiteness value is used for printed products with a short text.

Whereas Whiteness refers to the shade of paper, brightness measures the amount of reflectance of a specific wavelength of blue light. It is important for the colour perception and the right print settings.

Gloss and roughness of paper

The most important surface properties are gloss and roughness. Both parameters affect the final printing products and are inversely proportional. The higher gloss, the lower roughness and vice versa. The most commonly used method to measure the gloss of paper is the Lehmann gloss meter, which measures the amount of direct light reaching the surface at 75 degrees. To measure the roughness of paper, two methods are used – BEKK and BENDTSEN.

Wide scale of types of paper with various properties leaves space for creativity and interesting visualisations of various prints. Although paper may seem to be less important part of printing products, it affects the economic efficiency and communication to a large extent.

In cooperation with the ANTALIS company .

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