Over deze norm
Applicable only to clear, slightly coloured liqids. Such colour characteristics are described as brownish-yellow. The principle is based on a visual comparison of the colour of a sample with that of colour standards. The results are expressed in terms of the platinum-cobalt scale. For routine control purposes a comparator, colorimeter or spectrophotometer may be used, if the values so obtained are identical with those obtained by visual comparison.
||Liquid chemical products - Measurement of colour in Hazen units (platinum-cobalt scale)