ISO 5350-1:2006 specifies a method for the estimation by transmitted light of the visible dirt and shives in laboratory sheets prepared from pulp. It is, in principle, applicable to all kinds of pulp, although it is mainly intended for pulp that is not manufactured in sheet form.

ISO 5350-1:2006 can also be applied to mill sheeted pulp, if the sheets have high grammage or are very opaque for other reasons, in which case ISO 5350-2:2006 is not applicable.

ISO 5350-1:2006 is not intended for recycled pulp.