I have talked to BATF, you are an alien in the US, and it is illegal to possess BP, because it is listed as an explosive.
So, only a US citizen can bring 8kg's of BP into Canada.
Cheers nessy.
It is an explosive but ATF does not regulate amounts under 50 lbs. For listed uses under TITLE 18 USC SECTION 845 ATTACHED. ANTIQUE FIREARMS EXEMPTION. Hence relief from GCA AND ATF regulations for non immigrant aliens. If you had 50. 1 lbs then required relief for possession of explosives.
Under 50 no licence required. Though it is an explosive. Black powder in listed amounts is not ammunition.
845. Exceptions; relief from disabilities
(a) Except in the case of subsections (!1) (l), (m),

, or (o) of section 842 and subsections (d), (e), (f), (g), (h), and (i) of section 844 of this title, this chapter shall not apply to: (1) any aspect of the transportation of explosive materials via railroad, water, highway, or air which are regulated by the United States Department of Transportation and agencies thereof, and which pertain to safety; (2) the use of explosive materials in medicines and medicinal agents in the forms prescribed by the official United States Pharmacopeia, or the National Formulary; (3) the transportation, shipment, receipt, or importation of explosive materials for delivery to any agency of the United States or to any State or political subdivision thereof; (4) small arms ammunition and components thereof; (5) commercially manufactured black powder in quantities not to exceed fifty pounds, percussion caps, safety and pyrotechnic fuses, quills, quick and slow matches, and friction primers, intended to be used solely for sporting, recreational, or cultural purposes in antique firearms as defined in section 921(a)(16) of title 18 of the United States Code, or in antique devices as exempted from the term "destructive device" in section 921(a)(4) of title 18 of the United States Code;