Art Masking Fluid is a must have in your watercolor tool box. It does a great job preserving the white spaces on your painting that may be too small to navigate around. Essentially it is like a liquid masking tape. If you want some areas in your painting to stay white then you paint the masking fluid over those areas, let it dry and then start your painting! When the painting is dry you can just rub off the dried glue and the paper will be white underneath!
When applying the masking fluid, we recommend using something other than your nice paint brush since it can gunk up the nice brushes. Make sure not to shake your masking fluid either as it may hurt the integrity of the product.