For this exercise, the idea is to tone your canvas, paint in a sketch of your subject, and wipe away the toned areas to reveal the light areas. She uses oils, but I thought the technique might work with gouache on a gessoed surface since gouache lifts with water. So I put down a coat of Liquitex Basics gesso and applied a thin coat of yellow ochre + burnt sienna gouache. Then I sketched in the mug with burnt sienna using a 1/4" flat brush. To wipe away the toned areas on the lightest values, I scrubbed with a damp cloth and brush. This was too aggressive and I peeled away some of the gesso and paper, but the effect is awesome.
After adding the darkest values, it was complete. Even though wiping away the base layer of paint didn't work very well, it's obvious where the value changes are.
I loved this technique! I think if I tried again using my cheaper Decoart gesso, which has a smoother surface that paint lifts off of easier (which I discovered in yesterday's sketchbook painting) I'd have better luck.