Colour fastness to metals

This method is intended for determining the effect on the colour of a dye, of dyeing in the presence of metals (iron and copper or their salts) either used in the construction of dyeing machinery or resulting from water and steam used in dyeing.
PRINCIPLE
The difference in colour between dyeings made in the presence and in the absence of salts of the metal is assessed with the grey scale.
For detail click here:http://www.dfmg.com.tw/member/standard/bs/BS-Z02.HTM