Well, I couldn't find it at the local Fabricland, nor the nearest three, nor the huge one on Ottawa street. It turns out they've discontinued it! And, moreover, the company that makes it has been acquired by another, and they don't really exist anymore!
I happened to get the one employee from the old company on the phone, and she knew what I was talking about, and found me some old stock buried in the warehouse somewhere. I had to buy a lot of it, though.
It's just my luck that the trim I base a whole article of clothing on goes discontinued just in time for all stock to run out at the time I've discovered I need more.
