ISO 2370:2019 specifies three permeametric methods for the determination of the fineness of flax fibres.
— Constant flow method, with two compressions, using a test piece of parallel fibres (see Clause 5);
— Simplified constant flow method, with one compression, using a test piece of fibres distributed “at random” (see Clause 6);
— Constant pressure method, with one compression, using a test piece of fibres distributed “at random” (see Clause 7).
This document is applicable to the various forms possible for flax fibres, i.e. long strands, broken strands, all kinds of tow and at all stages of manufacture of these substances.
