I was talking with The Bean recently about the joys of masking. We debated the pros and cons of frisket film vs. masking fluid. I am a huge fan of masking fluid because I can paint it directly onto my paper instead of having to wrangle with scissors and X-Acto blades to cut perfect shapes with frisket film. Masking fluid is essentially liquid rubber and when it dries in your brushes it renders them useless for painting. I have two brushes devoted solely to masking. When they get too gloopy, I pull the dried rubber off with my fingers.
For super straight edges, I use artist’s tape. The danger in any of these masking techniques is ruining your paper. For the most part, standard watercolor paper can stand up to the removal of masks, because it has been sized with gelatin (which acts as a sealant for the fibers of paper). I typically like working on unsized paper because of it’s softer texture. Most masking devices completely destroy the surface of unsized paper when I remove them. To combat this, I use a hair dryer to heat the rubber while I rub it off with a rubber cement block. If I am masking with tape, I stick it to my pants leg first to pick up a little dust so that there isn’t so much adhesive that may damage my paper. Even then, I may still use a dryer to loosen the glue.Be warned, colored masking fluid may stain your paper months after it has been removed. When I worked on Bird, I used a yellow masking fluid instead of white, thinking there was no difference. The work hung on my wall for a few months with no change in color, but when the paintings came back from my publisher, there were stains where the masking fluid had been used. Fortunately, it didn’t print in the artwork much, but as time went on, the masked areas darkened even more.
I now use colourless masking fluid by Winsor & Newton.
1. Only apply masking fluid to dry paper. If the fibers of your paper are wet or damp when you apply the fluid, the more likely it is that you will tear your paper upon removal.
2. Do not leave masking fluid on for extended periods of time. I recommend a day, tops. Again, the longer the fluid remains on your paper, it may stain or tear once removed.
3. Use a hair dryer when removing masking fluid from soft sized paper. The heat will loosen the adhesive quality and make it easier to remove.
4. Invest in a good rubber cement block for removal. You can use your finger, but the skin’s natural oils may leave stains on your work.
5. Remove masking fluid after your work is completely dry. Nothing is worse than spending an hour masking an area out, than smearing wet paint across your pristine masked shapes.
6. Dedicate brushes solely for applying masking fluid. For the most part, if you wash your brushes with soap and water immediately after you have used masking fluid, they will be fine. I am not that disciplined, so I have a set of brushes that are already firm from continued use.
7. Try other applications. Use color shapers, a toothbrush to splatter, finger, etc. to create interesting textures in your work.
Hope this is helpful!