That's called Crumpled Resist and it's a great technique!! I like to ink the cardstock and spritz it with water before crumpling. Then I unfold and use a darker ink to lightly go over the raised surface. I let this dry then I stamp on it (usually collage style with vintage type stamps) then stamp the entire card with versamark and use clear embossing powder. It's so pretty and you just want to keep touching it
I'm really into Polished Stone right now myself and I'm getting ready to try Faux Silk, Faux Suede, Distressed Paper, Northern Lights, Split Negative, Chalk Dragging, Masking Tape, and the Warhol Technique!!
So many techniques... so little time!!
Mary