Paper doesn’t play its usual passive role in the watercolors of [Alexander Nepote] … “I don’t fear losing the white paper,” Nepote explains. “I just put more on. By adding paper I can regain ‘light’ lost …— Lawrence C Goldsmith, Watercolor Bold & Free, p151
Collage is usually adding in something colourful, patterned or textured to advance a painting. And regaining white areas is typically done by painting with white or gesso. Collaging with bits from another sheet of your original paper not only regains the white but also the qualities of the original surface. And now I’m wondering why I haven’t ever done this.