ASTM D3776-07 pdf free download.Standard Test Methods for Mass Per Unit Area (Weight) of Fabric.
6. Conditioning
6.1 Condition test specimens as directed in Practice D 1776.
6.2 All weighing tests should be made in the standard atmosphere for testing textiles (20 ± 1°C (70 ± 2°F), 65 ± 2 % RH), after the specimens have been conditioned in the same atmosphere. It may be impractical to condition the specimens in Option A or nonconditioned testing may be agreed upon by the purchaser and supplier. When the full rolls or bolts of fabric cannot be properly conditioned in a reasonable time with available facilities, perform the tests without conditioning and report the actual conditions prevailing at the time of the test. Such results may not correspond with the results obtained after testing adequately conditioned specimens in the standard atmosphere for testing textiles.
7. Option A—Full Piece, Roll, Bolt, or Cut
7. 1 Significance and Use
7.1 .1 Option A for the determination of mass per unit area of woven fabrics may he used for acceptance testing of commercial shipments since it has been used extensively in the trade.
7.1.2 In case of a dispute arising from differences in reported test values when using Test Methods D 3776 for acceptance testing of commercial shipments. the purchaser and the supplier should conduct comparative tests to determine if there is a statistical bias between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the two parties should take a group of test specimens which are as homogeneous as possible and which are from a lot of material of the type in question. The test specimens should then be randomly assigned in equal numbers to each laboratory for testing. The average results from the two laboratories should he compared using student’s (-test for unpaired data and an acceptable probability level chosen by the two parties before testing is begun. If a bias is found, either its cause must he found and corrected or the purchaser and the supplier must agree to interpret future test results in the light of the known bias.
7.2 Sampling—As a lot sample for acceptance testing. take at random the number of rolls of fabric as directed in an applicable material specification or other agreement between the purchaser and the supplier. Consider rolls of fabric to be the primary sampling units. Consider the rolls of fabric in the lot sample as the laboratory sample and as the test specimens.
7.3 Procedure:
7.3.1 Measure the length of the lull piece, roll, bolt, or cut by the hand procedure in Test Method D 3773.
7.3.2 Measure the width by the tension-free alternative of Option A of Test Method D 3774.
7.3.3 Weigh the fabric, with shell and holder, if any, to the nearest 0. 1 % of its mass.
7.3.4 Weigh the holder, if any, to the nearest 0.1 % of its mass.
7.4 calculations:
7.4.1 Determine the net weight of the fabric by subtracting the weight of the holder from the total weight.
7.4.2 Dimensions and mass may all be determined in SI units and mass per unit area calculated using Eq 1, Eq 2, or Eq 3, as follows.ASTM D3776 pdf download.