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The Cranberry Corner No. 10

Paper Basis Weight/Grammage

From the earliest days of papermaking in Europe the "Basis Weight" of paper for various grades has been measured by the weight in pounds of a given number of sheets of a given dimension, which is called a "Ream". ( "rame" in French, "Ries'' in German, "resma" in Spanish, from "rizmah" ( a bundle of paper ) in Arabic. (1)

Each grade of paper had it's own name, end-uses and ream size, such as the following examples used in England: ( 2 )

Other countries had their own ream names and sizes.

The number of sheets in a ream also varied according to the grade and was normally 480 or 500 sheets. The 480 number is equivalent to twenty quires of 24 sheets each. (1)(3)

The ream size of modern art papers is 22" x 30" - 500 sheets.

In recent times with the more widespread adoption of the metric system, (more correctly known as the "S.I." or "systeme internationale") except for certain fine art and handmade papers "Basis Weight" has been replaced by "grammage" as the unit of measurement of the weight per unit area of paper.

Grammage is simply the weight in grams of one square metre of paper, and is expressed as "grams per square metre" or "gsm".

To convert to grammage in grams per square metre from Basis Weight in pounds per ream of 22"x30" - 500 sheets multiply by 2.1305. Each ream size has it's specific conversion factor.

References:

( 1 ) Papermaking by Dard Hunter, Alfred A . Knopf Inc. New York, 1947

( 2 ) The Paper Trade Diary Directory of Great Britain, Trade Journals Ltd., London, 1935.

(3) Modern Papermaking by Robert H. Clapperton and William Henderson, Basil Blackwell, Oxford 1941

Edward H. Snider (c) 1998

CRANBERRY M I LLS Handmade Papers, 613 - 387-1021

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