ASTM D3776-09 pdf free download.Standard Test Methods for Mass Per Unit Area (Weight) of Fabric.
11 .2 Report the following information:
11.2.1 Option used to measure fabric mass per unit area.
11.2.2 Fabric mass in ounces per square yard. or ounces per linear yard. or in yards per pound. to three significant figures.
11 .2.3 Fabric mass in grams per square metre, or grams per linear metre, or metres per kilogram. to three significant figures.
1 1.2.4 Fabric width if mass is reported as mass per linear metre (yard) or metres per kilogram (yards per pound).
11.2.5 State whether the fabric weight includes or does not include selvages, and
11.2.6 Atmospheric conditions under which the tests were conducted and whether the specimens were conditioned as directed in Practice D 1776.
12. Precision and Bias
12.1 Swnmarv—In comparing two averages of four observations when using Option B of Test Methods D 3776, the difference should not exceed the following amounts in 95 out of 100 cases when all of the observations were taken by the same well-trained operator using the same piece of equipment and specimens randomly drawn from the same sample of material:
Larger differences are likely under all other circumstances. The procedure in Option B of Test Methods D 3776 has no known bias and is used as a referee method.
12.2 Interlaboratory Test Data—An interlaboratory test was run in 1981 in which randomly drawn specimens of four materials were tested in each of four laboratories using Option B of Test Methods D 3776. Two operators in each laboratory each tested two specimens of each material for mass per unit area. The first fabric was a 65 % polyester and 35 % cotton seersucker type basket weave. The second fabric was a 65 % polyester and 35 % cotton gingham check. The third fabric was an 88 % cotton and 12 % polyester corduroy. The fourth fabric was a 100 % cotton denim. The components of variance for fabric mass per unit area expressed as standard deviations were calculated to he as follows:
NOTE I—The square roots of the components are being reported to express the variability in the appropriate unit of measure rather than as the square of those units of measure.
12.3 Precision—For the components of variance reported in
12.2, two averages of observed values should he considered significantly different at the 95 % probability level if the difference equals or exceeds the critical differences in Table 1.
NOTE 2—The tabulated values of the critical differences should be considered to he a general statement, particularly with respect to between- laboratory precision. Before a meaningful statement can be made about two specific laboratories, the amount of statistical bias, if any. between them must be established with each comparison being based on recent data obtained on specimens taken from a lot of material of the type being evaluated so as to be as nearly homogeneous as possible and then randomly assigned in equal numbers to each of the laboratories.
12.4 Bias—Option B in Test Method 1) 3776 for measuring mass per unit area (weight) of full width samples has no known bias and is accepted as a referee procedure. The accuracy of the other procedures in Test Method D 3776 has not been established. Weights of unconditioned fabric will he affected by the past history of the product.
13. Keywords
13.1 fabric; mass per unit area; weight.ASTM D3776 pdf download.