Masking fluid is a nifty tool to use with the Koh-I-Noor watercolor wheel. You can create crisp, geometric lines within the brilliant colors of your watercolor wheel in a few easy steps.
1. Draw out your line art using a masking fluid -- these can come in a variety of delivery systems. For instance, Molotow makes a masking pen that delivers a thin coating of masking fluid in a precise line. Grumbacher makes a masking fluid that you can dip a glass pen, stylus, or brush into for a thicker application. Let the masking fluid dry.
2. Using a wet-in-wet technique, coat your sheet of paper with a clean brush dipped in water. You can layer the water right over your masking fluid.
3. Next, paint your watercolor into the wet layer of water on your sheet of paper. You can layer and blend your colors. Letting the color dry between layers can result in a more saturated look, while building up wet layers and letting them run can also offer unique results.
4. Let your paint dry, depending on how much water you've used; this could take up to a few hours. Don't let your work sit for more than 24 hours, as the masking fluid will become more difficult to remove.
5. After the painting has dried, gently rub the masking fluid with your finger to remove it from the paper. You can also use a vinyl eraser to remove the masking fluid; this will also remove some of the watercolor giving your linework a slight glow.
6. You can experiment with a wide range of colors and methods of working with masking fluid and watercolor. It's easy to store your finished pieces in a journal format using the Grumbacher and Koh-I-Noor papers that feature the In & Out Pages. You can simply press the domes back into the binding, keeping a record of the effects you've been able to create.