Hearings under section 4(d) of the act will be held when deemed by the Commission to be in the public interest. Interested persons may file applications for such hearings. Such applications shall be filed in quadruplicate and shall contain a detailed technical description of the class or classes of articles or products regarding which applicant requests a determination and announcement by the Commission concerning express or implied representations of fiber content of articles or concerning insignificant or inconsequential textile content of products.