The provisions of this chapter shall not apply (a) to any common carrier, contract carrier, or freight forwarder in transporting a product, fabric, or related material shipped or delivered for shipment into commerce in the ordinary course of its business; (b) to any converter, processor, or finisher in performing a contract or commission service for the account of a person subject to the provisions of this chapter: , That said converter, processor, or finisher does not cause any product, fabric, or related material to become subject to this chapter contrary to the terms of the contract or commission service; or (c) to any product, fabric, or related material shipped or delivered for shipment into commerce for the purpose of finishing or processing such product, fabric, or related material so that it conforms with applicable flammability standards issued or amended under the provisions of .section 1193 of this titleProvided