Masking fluid is, essentially, liquid rubber. It adheres to the paper and protects an area from watercolour. When the paint dries, you simply remove it. There are different types of masking fluid, like the ones you apply with a brush. But if you’re like me and want to cut the crap with RUINING BRUSHES: look no further. I exclusively use Molotow masking liquid pens now.
You don’t need sacrificial brushes. It’s tinted blue so you can see where the hell it is. The future is here.
Rolls on like a kickass pen
Let it dry, slap on your watercolour
Coax it off with an eraser
Bam look at that. Perfect for those details you want to stay white. Not recommended for application over large areas. Available on Amazon.