This part of ISO 5350 specifies a method for the estimation by transmitted light of the visible dirt and shives in pulp manufactured in sheets. It does not apply to unbleached kraft pulps or to any other sheeted pulps that are too opaque to allow for the estimation of the minimum size or for minimum contrast specks to be counted in accordance with this International Standard. The maximum grammage for most pulp sheets is in the range 800 g/m2 to 1000 g/m2.
If the sheets of the mill sheeted pulp have high grammage or are very opaque for other reasons, Part 1 of this International Standard shall be applied.
NOTE For thick sheets, with highly textured surfaces and/or with density variations, wetting the sheet will cause optical variations, called lens distortions that will distort the perceived size of a dirt speck reducing the precision of the size estimation. Alternatively, pulp the sheet and recast it as a laboratory sheet and then use Part 1 of this International Standard.
This International Standard is not intended for recycled pulp.