The newest Mini-Challenge at Unity Stamp Company is called Grounded to Space … using an inky background to ground something that isn't on the ground (i.e. air or sea). I don't remember every consciously doing this technique before, so I had to give it a try.
The only Unity Stamp I could find in my stash that fit the theme was this Airplane from For the Guys. I decided to "ground" it by using white pigment ink on blue cloud stock to create a cloudy sky … I used a triangle of sponge and a hand-cut curvy edge to create my sky.
When I stamped the plane on top of the clouds, the ink was lighter where it stamped over the pigment, making it look like it was trying flying through the clouds … happy accident.
Super background!! great card.