I did a frame with less than 500ml - powder coating comes off particularly easily with Nitromors - it bubbles up and then you can peel it like a satsuma, very satisfying.
I know everyone says it and it has already been said, but beware of Nitromors' peppery goodness, wear googles, it's a paste, you can easily get a little flick into your lovely Irish/Scottish/French eyes.
Watch the powdercoat give in to the power of Nitromors:
me too, just brushed it on really lightly and it worked a treat. Perhaps 1/2 a small bottle.