NBN EN ISO 15755:1999

This European Standard specifies the test method for the estimation by reflected light of the visible contraries in paper. Visual inspection is applicable to most kinds of paper and board. Paper and board with an apparently high content of contraries require to be inspected by instrumental means as described in Annex B, as the tedium of large counts diminishes the judges' precision. However, papers which are not flat, have a low lightness (value below 30 %) and contain holes that may cause particular problems for instrumental techniques (see Annex B).