Under-colouring with distress inks. |
You just wet a piece of thickish (ideally water colour) paper, ink up your stamp with distress inks and stamp them down onto the wet page, Leave them there for a little while so that the colours soak and spread.
Dry the page (either with a craft heat gun) or leave it to dry naturally, then re-ink your stamp with black ink (I used Versafine), and stamp on top of the blurry coloured image to add back the detail.
That's pretty much it!