I discovered this technique using plastique wrap in Claudine Hellmuth's book "Collage Discovery Workshop", but with acrylic paint. I use it several time and love this technique !
I then saw this video on Youtube doing the same, but with Glimmer Mists (by Tattered Angels), and thought i should give it a try.
It's easy, except the drying time that can be long if you spray a lot of mist, it's quick to create.
And the final result is just gorgeous !
I do a lot of mixed media art, and you can used the Workable Fixative spray (brand: Krylon) so you'll be able to work on it without smudging it. OR you heat dry it, and spray an hairspray over (thanks to my friend Scrapacat for this tip).