This International Standard specifies a method of determiningThe water absorptiveness of sized paper and board, including corrugated fibreboard, under standard conditions. It may not be suitable for paper of grammage less than 50 g/m2 or embossed paper. It is not suitable for porous papers such as newsprint or unsized papers such as blotting paper or other papers having a relatively high water absorpiiveness for which ISO 8787 is more suitable.
EN 20535:1994 history
1994EN 20535:1994 Paper and Board - Determination of Water Absorptiveness - Cobb Method (ISO 535 :1991)