This part of ISO 7211 specifies three methods for the determination of the number of threads per centimetre in woven fabrics. Any of the three methods may be used, the choice depending on the character of the fabric. However, in case of dispute method A is recommended. Method A: Dissection of fabric, suitable for all fabrics. This is the most laborious method but has fewer limitations than the others; in particular, it is the only one that is really suitable for the examination of certain folded structures and other complicated weaves.
Method B: Counting glass, suitable for woven fabrics with more than 50 threads per centimetre.
Method C: Traversing thread counter, suitable for all fabrics. Where the number of threads per centimetre is low, it may be convenient to express the results as the number of threads per decimetre. NOTE - Methods using parallel line gratings and tapered line gratings have been given in the annex for information. These methods have not been considered accurate enough to be used as standard test methods but can be used to give rough and ready estimates for routine testing.