TL 226 and PV 3906 are carried out on CrockMaster.
These standards specify to use nettle fabric as per DIN EN ISO 105-X12.
DIN EN ISO 105-X12 is an adoption of EN ISO 105-X12, which specifies the use of a ‘cotton rubbing cloth,’ the specification for which can be found in EN ISO-F09. There is no inclusion of the term ‘nettle fabric’ in either standard.
It would appear that there has been a mis-translation in TL 226 and PV 3906, and that the term ‘nettle fabric’ appears in these standards in place of the term ‘crocking cloth.’
James Heal supplies crocking cloth for these standards as a pack of 500, 5cm x 5cm pieces, under stock code 702-540.