BS EN ISO 536:2020 pdf download – Paper and board — Determination of grammage

BS EN ISO 536:2020 pdf download – Paper and board — Determination of grammage 5.2 Balance, sufficiently accurate, over the range of mass for which it is used, to measure the test piece mass to within 0,5 % of the actual mass. It shall be sensitive enough to detect a change of ±0,2 % in the mass to be weighed and, if the balance is of the direct-reading type, it shall be graduated so that readings may be taken to this degree of accuracy. 5.3 Special sheet-weighing balances, designed to weigh test pieces of a given size and which indicate grammage directly, may be used, provided that the above conditions for determination of mass are fulfilled and that the area of each test piece on a single weighing is not less than 50 000 mm 2 (500 cm 2 ) and not more than 100 000 mm 2 (1 000 cm 2 ) (see Clause 8 and 9.2). When in use, the balance shall be shielded from air currents. 6 Sampling The selection of units and sheets and the taking of specimens shall be carried out in accordance with ISO 186. If tests are made on another type of sample, make sure that the specimens taken are representative of the sample received. If possible, take at least five specimens and take an area sufficient for at least 20 test pieces. If the “as taken” grammage is to be determined, the influence of the ambient atmosphere on the moisture content of the specimens shall be minimised (see A.2). 7 Conditioning For the determination of conditioned grammage, and “oven-dry” grammage, the specimens shall be conditioned in accordance with ISO 187. 8 Procedure For the determination of conditioned grammage, prepare and weigh the test pieces in the same atmospheric conditions as used to condition the specimens. For the determination of conditioned grammage and oven dry (see A.1) grammage, using the cutting device (5.1), cut test pieces from conditioned specimens. If possible, cut at least 20 test pieces from at least five specimens, taking the same number from each specimen. For the determination of “as- taken” grammage, follow the same procedure, minimising the influence of the ambient atmosphere on the moisture content of the test pieces (see A.2). Whenever possible, each test piece shall have an area of not less than 50 000 mm 2 (preferably 200 mm × 250 mm) and not more...