Masking fluid is a liquid rubber solution that is applied to the watercolor paper to save parts of the white paper.
Stones in water - Erik Lundgren Watercolor
An Onion, a simple exercise - Erik Lundgren Watercolor
One way to use masking fluid in watercolor - University fountain
Hydropower - an exercise - Erik Lundgren Watercolor
Bymon - an easy exercise - Erik Lundgren Watercolor
Beginner's mistakes 2 - Erik Lundgren Watercolor
Watercolor Painting : Window
The towers of San Gimignano A watercolor painting
Draw fine lines - Erik Lundgren Watercolor