Hi Manon,
Our member Markie's Mom made this technique popular. All you do is spray a piece of glossy cardstock with water and drizzle different colors of reinker (at least two) over the cardstock. Next spray another piece of glossy cardstock and press it glossy side down on your first glossy cardstock piece.It will make great backgrounds.
This technique was a technique challenge a little ago.:
Forums at Splitcoaststampers
I hope this helps. Hugs and smiles
Beate
splitcoaststampers