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 part of ISO 5350. The maximum grammage for most pulp sheets is in the range 800 g/m2 to 1 000 g/m2. If the sheets of the mill sheeted pulp have high grammage or are very opaque for other reasons, ISO 5350-1 should 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, thus reducing the precision of the size estimation. Alternatively, use ISO 5350-1 to disintegrate the sheet and to prepare laboratory sheets for the size estimation. This part of ISO 5350 is not intended for recycled pulp.