WW2 Canvas Material

[rob love]

I always see the canvas described as cotton duck when I am ordering it through the supply system. Here is a chart from Wikopedia:
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:[1]

• No. 1 (18 oz): hammocks, cots, sandbags
• No. 2 (17 oz): hatch paulins
• No. 3 (16 oz): heavy-duty bags
• No. 4 (15 oz): sea bags
• No. 5 (14 oz): heavy work clothes
• No. 6 (13 oz): large boat covers, heavy work clothes
• No. 8 (11 oz): work clothes, clothes bags
• No. 10 (9 oz): work clothes, shower curtains
• No. 12 (7 oz): light clothes

Number duck classifications per square yard There is often confusion when it comes to matching up weights and the correct number duck classification. The table below accurately represents the weight and number duck classification[5] per square yard instead of linear yard 22 inches wide.

• No. 1 (30 oz/sq yd or 1,000 g/m2): floor & wall covering, sound absorption, equipment covers, heavy bags, horse packs, storage bins
• No. 2 (28 oz/sq yd or 950 g/m2): hatch paulins
• No. 3 (26 oz/sq yd or 880 g/m2): sea bags
• No. 4 (24 oz/sq yd or 810 g/m2): heavy-duty work clothes, hammocks, sand bags, director chairs, place mats, belting
• No. 5 (23 oz/sq yd or 780 g/m2): heavy work clothes
• No. 6 (21 oz/sq yd or 710 g/m2): utility bags, place mats, belting
• No. 8 (18 oz/sq yd or 610 g/m2): backpacks, painted floor cloths, tents, tarps, awnings, work clothes, clothes bags
• No. 10 (14.75 oz/sq yd or 500 g/m2): artist canvas, murals, shower curtains, painted floor cloths, hammocks, clothes
• No. 12 (11.5 oz/sq yd or 390 g/m2): stretched artist canvas, furniture slip covers, light clothes

Often the NSN description will include the term "cotton duck no. X" with X being the classification.