Grammage and basic weight , in pulp and paper and in the fabric industry, is the density of paper or cloth products, ie their mass per unit area. Two ways of expressing grammage are commonly used:
- Expressed in units of grams per square meter (g/m 2 ), paper density is also known as grammage . This is a measure used in most parts of the world.
- Expressed in units of mass (expressed as weight) per number of sheets, this is known as base weight . The conventions used in the United States and some other countries that use US paper sizes are 500 pound rim (or in some cases 1000) sheets of the given base size (raw, still cut). Japanese paper is expressed as weight in kg of 1,000 sheets.
Video Grammage
Grammage
In metric systems, the mass per unit area of ​​all types of paper and paperboard is expressed in grams per square meter (g/m 2 ). This quantity is commonly called grammage in English and French (ISO 536), although printers in most English-speaking countries still refer to "heavy" paper.
Typical office paper has 80 g/m 2 , therefore a typical A4 sheet ( 1 / 16 m < soup> 2 ) weighs 5 g. Unofficial "gsm" unit symbols instead of the standard "g/m 2 " are also widely found in English-speaking countries.
Usually grammage is measured in an on-line paper mill with a quality control system and verified by laboratory measurements.
Maps Grammage
Weight base
In countries that use US paper sizes, the less direct measure known as weight is used in addition or in lieu of grammage. The basic weight of paper is the density of paper expressed in the dimension of the given dimension rim and the number of sheets. In the US system, the weight is determined in pound avoirdupois and the number of reams of paper is usually 500 sheets. However, the specified mass is not the mass of reams sold to customers. Instead, it is an unreleased "base mass" mass in which the sheet has a larger size. Often, this is a measure used during the manufacturing process before the paper is cut to the dimension in which it is sold. So, to calculate mass per area, one should know
- rim base mass,
- the number of sheets in the ream, and
- dimensions of the "cut" sheet on the ream.
The standard dimensions and number of rim sheets vary according to the paper type. This "uncut" base size is usually not labeled on the product, not formally standardized, and therefore should be guessed or inferred from trading practice. Historically, this convention is a product of pragmatic consideration such as the size of a printed sheet.
Using the same base sheet size for the same paper type, consumers can easily compare papers from different brands. Twenty-pound bond paper is always lighter and thinner than 32 pounds bond, no matter what the cut size is. And 20 pound bond letter size and 20 pound bonds are legal sizes are paper weighing the same size as different pieces.
However, a piece of general photocopy paper with a base weight of 20 pounds (9.1 kg) does not have the same mass of paper as the same size of coarse paper (newspaper). In the previous case, the standard ream was 500 sheets of 17-by-22-inch paper (432 x 559 mm), and the last, 500 sheets of paper 24-by-36-inch (610 x 914 mm). Here are some basic measures for different types of paper. Units are inches unless noted.
The 17 x 22 inch (432 x 559 mm) sheet can be cut into four 8.5 x 11 inch (216 x 279 mm) sheets, a standard for conventional business stationery as letter-size paper . Thus, the 17-by-22-inch (432 x 559 mm) rim becomes commonly used. The 25-by-38-inch (635 by 965 mm) rim-paper book is developed because such sizes can be easily cut into sixteen by 9-inch (229 mm) booklets without significant waste.
The original newspaper press printed a 2 to 3 foot (0.610 x 0.914 m) sheet in size, allowing the dimension of the rim for the mold to be 24 x 36 inches (610 x 914 mm), with 500 sheets to the ream. Newspaper paper is made of wood pulp, and wooden paper (wallpaper) paper is made on newsprint presses. Newspapers are used as wrapping paper, and the first paper bags are made from newsprint. Standard newsprint is also standard for packaging papers, although in packaged paper kraft and non-wood pulp are used for greater strength.
Paper weight is sometimes expressed using the symbol "#". For example, "20 #" means "20 pounds per 500-sheet bottom rim". When paper ream density is given in pounds, it is often accompanied by "weight M". Weight M is the weight (in pounds) of 1000 pieces of pieces. Paper suppliers often fill with M weight, as it is always consistent in a certain paper size, and therefore allows simple weight calculations for shipping costs.
For example, a 5-by-11-inch (216 x 279 mm) 20-inch rim paper can be determined "10 M". 1000 pieces of cut (or two reams) will weigh 10 pounds (4.5 kg), half of the four reams of paper cut out of a 17-by-22-inch (432 x 559 mm) baseline paper base sum.
Caliper
The thickness of the paper, or caliper, is the general size that is determined and required for a particular printing application. Since paper density is usually unknown or directly determined, the thickness of each sheet of paper can not be calculated by any method. Instead, it is measured and determined separately as a caliper. However, paper thickness for most general business papers may be similar across comparable brands. If the thickness is not specified for the paper in question, it must be measured or guessed based on comparable paper specifications.
Caliper is usually measured in micrometers (Ã,Âμm), or in the US also in miles (1 million = 0.001 in = 25.4 Ã,Âμm). Generally, the 20-lb bond ranges from about 0.0038 to 0.0045 inches (97 to 114 m) in thickness.
See also
- Density
- Area density
- Linear density
References
External links
- Paper Weight - Conversion Chart
- Understanding the Weight of Paper
- Understand paper weight (Staples, Inc.)
- M-weight Calculator
- Paper Weight Calculator
Source of the article : Wikipedia
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