16 C.F.R. § 300.28
(a) Where a wool product is composed in part of various man-made fibers recovered from textile products containing underdetermined qualities of such fibers, the percentage content of the respective fibers recovered from such products may be disclosed on the required stamp, tag, or label, in aggregate form as “man-made fibers” followed by the naming of such fibers in the order of their predominance by weight, as for example:
60% Wool 40% Man-made fibers Rayon Acetate Nylon
(b) Where a wool product is composed in part of wool, or recycled wool and in part of unknown and, for practical purposes, undeterminable non-woolen fibers reclaimed from any spun, woven, knitted, felted, braided, bonded or otherwise manufactured or used product, the required fiber content disclosure may, when truthfully applicable, in lieu of the fiber content disclosure otherwise required by the Act and regulations, set forth (1) the percentages of wool or recycled wool, and (2) the generic names and the percentages of all other fibers whose presence is known or practically ascertainable and (3) the percentage of the unknown and undeterminable reclaimed fibers, designating such reclaimed fibers as “unknown reclaimed fibers” or “undetermined reclaimed fibers,” as for example:
75% Recycled Wool—25% Unknown Reclaimed Fibers. 35% recycled Wool—30% Acetate—15% Cotton—20% Undetermined Reclaimed Fibers.
In making the required fiber content disclosure any fibers referred to as “unknown reclaimed fibers” or “undetermined reclaimed fibers” shall be listed last.
[29 FR 6626, May 21, 1964, as amended at 45 FR 44262, July 1, 1980; 45 FR 49542, July 25, 1980]