ASTM D646-96 pdf free.Standard Test Method for Grammage of Paper and Paperboard (Mass Per Unit Area)
Condition and test the test specimens in an atmospherein accordance with Practice D 685，unless grammage”asreceived” is required.
The precision of this work is such that hysteresis hasimportant effects; therefore, precondition the test specimens sothat the equilibrium moisture content is approached from thedrier state.If the cutting accuracy specified in 5.2 is attained (see7.2), use the mean area obtained in 7.2; otherwise, determinethe area of each test specimen to within 0.3 %, that is, measurethe dimensions of each sheet to within 0.2 %.If the special sheet-weighing device is used, be sure thatthe dimensions of the sheets are within 0.2 % of the requiredsize; 11.1 Report the grammage in grams per square metre tothree significant figures for each test unit and, if required, forthe average of the test units drawn from the lot. If the test units have been taken from more than oneposition across a roll or sheet and information on grammagevariation is required (for example, Note 2), report the averagefor each position separately.
If desired, the results may also be reported in poundsfor customary trade sizes. If the total area of a test unit is less than that specified,state the actual total area tested. The above values of precision are averages calcu-lated from 18 reports of the TAPPI Collaborative ReferenceProgram for Paper. Each test result is an average for approxi-mately 5000 cm2 of paper and paperboard.The user of this precision data is advised that it isbased on actual mill testing, laboratory testing, or both.Thereis no knowledge of the exact degree to which personnel skillsor equipment were optimized during its generation. Theprecision quoted provides an estimate of typical variation intest results which may be encountered when this standardmethod is routinely used by two or more parties.The procedure in this test method has no biasbecause the value of grammage is defined only in terms of theconditions stated in the test method.ASTM D646 pdf download.