ASTM D3776-96 (2002) pdf free.Standard Test Method for Mass Per Unit Area (Weight) of Fabric.
1 Report the following information:
1.1 Option used to measure fabric mass per unit area.
1.2 Fabric mass in ounces per square yard, or ounces per linear yard, or in yards per pound, to three significant figures.
1.3 Fabric mass in grams per square metre, or grams per linear metre, or metres per kilogram, to three significant figures.
1.4 Fabric width if mass is reported as mass per linear metre (yard) or metres per kilogram (yards per pound).
1.5 State whether the fabric weight includes or does not include selvages, and
1.6 Atmospheric conditions under which the tests were conducted and whether the specimens were conditioned as directed in Practice D 1776.
2. Summary- -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: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.
Precision- For the components of variance reported in 12.2, two averages of observed values should be considered significantly different at the 95 % probability level if the difference equals or exceeds the critical differences in Table 1.
The tabulated values of the critical differences should be considered to be a general staterment, particularly with respect to betweenlaboratory 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 recen 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 D 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 be affected by the past history of the product.ASTM D3776 pdf download.