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glossary/cobb-value

Cobb value

Also: Cobb, Cobb60, Cobb30

The mass of water absorbed by a paper in 60 seconds (Cobb60) per square metre, a standard water resistance measurement.

Cobb value measures how much water paper absorbs in a fixed time. The standard method floods a circular area of paper with water for 60 seconds (Cobb60) or 30 seconds (Cobb30), then weighs the water pickup. The result is expressed in g/m² of water absorbed.

Kraftliner and testliner typically target Cobb60 of 25 to 40 g/m². Lower numbers mean better water resistance. Food-grade and export packaging papers often hit 20 g/m² or below. The test is defined by ISO 535.