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Grammage and basis weight, in the pulp and paper industry, are the area density of a paper product, that is, its mass per unit of area. Two ways of expressing the area density of a paper product are commonly used: Expressed in grams (g) per square metre (g/m 2), regardless of its thickness [1] (known as grammage). This is the measure used in ...
Set-off is measured at two different time intervals, 0.35s and 3s. A freshly printed surface is pressed against a paper after 0.35s and after 3s. Then the set-off density is measured. The idea behind selecting these two timings is to know what will be the set-off when the materials are used in a high-speed press and a low-speed press.
The density can be calculated by dividing the grammage of paper (in grams per square metre or "gsm") by its caliper (usually in micrometres, occasionally in mils). [1] The "ISO 534:2011, Paper and board — Determination of thickness, density and specific volume" indicates that the paper density is expressed in grams per cubic centimeter (g/cm ...
The weight of an A-series sheet of a given paper weight can be calculated by knowing the ratio of its size to the A0 sheet. For example, an A4 sheet is 1 ⁄ 16 the size of an A0 sheet, so if it is made from 80 g/m 2 paper, it weighs 1 ⁄ 16 of 80 g (2.8 oz), which is 5 g (0.18 oz).
Similarly, two sheets of A4 can be scaled down to fit one A4 sheet without excess empty paper. This system also simplifies calculating the weight of paper. Under ISO 536 , paper's grammage is defined as a sheet's mass in grams (g) per area in square metres (unit symbol g/m 2 ; the nonstandard abbreviation "gsm" is also used). [ 5 ]
The paperboard sector is mainly looked at in conjunction with the paper industry. The Paper & Paperboard market size (2007) had a value of US$630.9 billion and a volume of 320.3 million metric tons. [5] Of that market 40.1% is European. About 50% of all produced paper is used for packaging, followed by printing and writing. [5]
In the US, paper density is usually measured in "pound per reams" (of 500 sheets). Typical Letter paper has a basis weight of paper of 20 or 24 pounds (9.1 or 10.9 kg) – the weight of 500 sheets (a ream) of 17-by-22-inch (431.8 by 558.8 mm) paper at 70 °F (21 °C) and at 50% humidity. [ 3 ]
Machine-finished coated paper (MFC) has a basis weight of 48–80 g/m 2. They have good surface properties, high print gloss and adequate sheet stiffness. MFC papers are made of 60–85% groundwood or thermomechanical pulp (TMP) and 15–40% chemical pulp with a total pigment content of 20–30%. The paper can be soft nip calendered or ...