§ 52. Use of nonofficial standards prohibited; sales by sample excepted

It shall be unlawful (a) in or in connection with any transaction or shipment in commerce made after , or (b) in any publication of a price or quotation determined in or in connection with any transaction or shipment in commerce after , or (c) in any classification for the purposes of or in connection with a transaction or shipment in commerce after , for any person to indicate for any cotton a grade or other class which is of or within the official cotton standards of the United States then in effect under this chapter by a name, description, or designation, or any system of names, description, or designation not used in said standards: Provided, That nothing herein shall prevent a transaction otherwise lawful by actual sample or on the basis of a private type which is used in good faith and not in evasion of or substitution for said standards.