This part of ISO 1833 specifies a method for analysis of viscose or certain types of cupro or modal or lyocell and flax fibres. This method is applicable, after removal of non-fibrous matter, to binary mixtures of - viscose or certain types of the current cupro or modal or lyocell fibres with - flax fibres. The method is not applicable to mixtures in which the flax fibre has suffered extensive chemical degradation, nor when the viscose, cupro, modal or lyocell fibre is rendered incompletely soluble by the presence of certain permanent finishes or reactive dyes that cannot be removed completely. This document has been prepared by Technical Committee ISO/TC 38 "Textiles", in collaboration with Technical Committee CEN/TC 248 "Textiles and textile products", the secretariat of which is held by BSI (United Kingdom). The responsible German committee is Working Committee NA 062-05-12 AA "Textilchemische Prüfverfahren und Fasertrennung" ("Testing methods for separation and chemistry of textile fibres") at the Material Testing Standards Committee (NMP) at DIN.