82.5—General specifications for straight colors.
No batch of a straight color listed in subpart B, C, or D shall be certified under this part unless:
(a)
It is free from all impurities (other than those named in paragraph (b) of this section or in the specifications set forth in such paragraph for such color) to the extent that such impurities can be avoided by good manufacturing practice.
(3)
In the case of a straight color which contains a barium salt listed in subpart C or D—soluble barium (in dilute HCl) (as BaCl2 ), not more than 0.05 percent.