NF EN 20534 : 1993

Explains two methods of measuring the thickness of paper and board and of calculating the apparent bulk density or the apparent sheet density from the thickness determinations. Not applicable to corrugated fibreboard and, to certain soft papers. It should be noted that two alternative pressures are permitted in the pressure of 100 kPa plus or minus 10 kPa is preferred. Covers normative references, definitions, principle, apparatus, sampling, conditioning, preparations of test pieces, procedure, expression of results, precision and test report.