An ink-based rather than acrylic based set of coloured washes. Simply apply the colour of your choice to part of a miniature, and the ink settles in all the grooves, and around the edges of all bumps and shapes, enhancing the look of your miniatures!
In this photo, I took two rebel pilots. The one on the left has washes applied to jumpsuit, vest and helmet. A dark red wash on the jumpsuit, a black wash on the helmet and vest. Now the shape of the helmet (earpiece, etc) stands out, and the lines in the vest are clearly visible now from a distance, and even the folds and ripples of the red jumpsuit now stand out more.
Citedal washes are a great way to show the details of the sculpture of the miniature, instead of simply relying on natural lighting to cast shadows and allow you to see the 3D elements of the miniature. I'm now applying washes to all miniatures I own, star wars, lord of the rings, battletech, etc. and am loving the effect it brings out.