Duck is classified according to weight in a numerical system, with grade 1 the heaviest and grade 12 the lightest variety. Besides this, traditional names exist, which are rarely used today. The classification system used today dates from the 1920s. A numbered duck classification system was put into effect by the Cotton Duck Association and the
United States Department of Commerce when discrepancies came about with various specifications and qualities of material. In a technical paper titled "Development of the Standard Numbered Cotton Duck Specification", the Department's
National Bureau of Standards established a set of specifications acceptable to manufacturer and consumer. ;Number duck classifications per linear yard, 22 inches wide Numbered duck is nominally made in weights from 1 to 12, but numbers 7, 9, and 11 are no longer used. Some typical uses of various grades (with weights in ounces) are: per square yard instead of linear yard 22 inches wide. • No. 1 (): floor & wall covering, sound absorption, equipment covers, heavy bags, horse packs, storage bins • No. 2 (): hatch paulins • No. 3 (): sea bags • No. 4 (): heavy-duty work clothes, hammocks, sand bags, director chairs, place mats, belting • No. 5 (): heavy work clothes • No. 6 (): utility bags, place mats, belting • No. 8 (): backpacks, painted floor cloths, tents, tarps, awnings, work clothes, clothes bags • No. 10 (): artist canvas, murals, shower curtains, painted floor cloths, hammocks, clothes • No. 12 (): stretched artist canvas, furniture slip covers, light clothes == See also ==