20. An employer who manufactures a controlled product referred to in the second paragraph of section 7 is not required to label that product if it is intended for sale or distribution and its container is labelled pursuant to the laws governing it according to paragraphs 1 to 5 of section 6.
Where the employer is preparing to affix such a label to the product but does not do so before the end of the shift during which the product is placed in its container, he shall place on or near that product a sign listing the information prescribed in section 17.