The fire element looks amazing because it does not look like Powder. How about do that with steam. I know that this would be a very hard task to accomplish, but I'm sure that many other players of The Powder Toy would love to see this implemented.
Steam is usually a blue-ish white colour? So maybe keep the type of movement the same as fire, but change the colour to steam.
I think steam is perfect as it is. Gas = bunch of particles, it's logical. Maybe the cooling tool could have the effect you're describing, like anti-fire.
boiling water should produce a lot more air pressure than it currently does, though. Especially at higher temperatures, like produced in my nuclear thermal rocket design, as that's what makes NT rockets better than chem, is their exhaust velocity.