if you scroll to the bottom , there are two distributors listed in Ontario (Richelieu)
Canada Richelieu Ottawa, ON 613-737-6571
Canada Richelieu Mississauga, ON 905-672-1500
I use Mohawk western finishing supplies here in Vancouver.
The Oxalic acid worked well on these black marks. It took most of them away and lightened the floor slightly.
I then did two coats of clear danish oil, then a couple more with some pigment and some terpentine in the mix, i applied that with sandpaper. I was able to slowly bring the color back up where I wanted. I followed that with three coats of clear polyurathane, and I am about to do hopefully the final coat using semi gloss poly. This turned out to be a LOT of work, but should last decades like that. The oil toughens the floor and brings up the color of the wood, and the poly creates a tough protective shell. this seems to work well with Fir, as it is quite hard wearing but a softer than a lot of the hardwoods.
Laminate would be so much easier, but in this case I really wanted to see the original woodwork. I liked the look with just the oil , but it didn’t seem that would be practical for a kitchen floor.