ISO 1833-7:2017 specifies a method, using formic acid, to determine the mass percentage of polyamide fibre, after removal of non-fibrous matter, in textiles made of mixtures of

- polyamide

with

- cotton, viscose, cupro, modal, lyocell, polyester, polypropylene, chlorofibre, acrylic, glass fibre, elastomultiester, elastolefin and melamine, or

- wool (if the wool content is less than or equal to 25 %), or animal hair fibres.

ISO 1833-7:2017 does not apply when the wool content exceeds 25 %; ISO 1833-4 applies.