I ended up buying 200-proof “food-grade” ethanol. “Food-grade” doesn't mean you should drink it; it means un-denatured - typically alcohol comes denatured with bad-tasting mixins to discourage young children from consuming.

My friend and I did some back-of-the-envelope calculations, and with the amount of rose petals I'm using, I could expect a drop of rose absolute. With “mechanical losses” like some getting stuck to the side of the jar, a drop basically comes out to nothing! My ego can't take that!

So I changed the plan: I'll leave some of the ethanol un-evaporated, and instead of “rose absolute”, where absolute refers to a pure, un-adulterated substance, I'll have “rose adulterate”.