I’d only ever used masking fluid once before, and it didn’t go all that well. I learned a lot, though, and when I tried it again this week, it worked splendidly. I feel that this qualifies me to give you advice.
Before the advice, though, a question: How long does masking fluid stay “good?” I ask because when I bought the fluid, it was… well… fluid. It’s been almost two years since then, and I didn’t open the jar once. This week, I opened it to find a custardy paste that didn’t budge, no matter how long I held it upside down and shook. The brush went right in, and after diluting it with water, it worked OK (save for a few chunks). I threw it out after that, because life’s too short to mess with chunky art supplies. But does anyone know the shelf life on the stuff?
Gooey questions aside, the experiment went surprisingly well. I used cold-press illustration board, masked an area, waited until it was dry (still sticky to the touch, though), and painted over and around it. Incidentally, I flattened out a piece of wax paper on the painting while it dried, which is how I got all those cool textured areas.
Once the paint was dry, I attempted to de-paint the masking fluid. Last time I masked something, I ended up smearing the paint that had dried on the mask all over the white area while I was removing it. This time, I tried to clean it… but the paint was stuck. So I recommend cleaning off the mask when the paint’s still wet.
I used this gummy eraser-type thing to remove the mask. It worked fabulously. I used a dragging motion in big swaths, much like you’d use a kneaded eraser on large areas of pencil. Some of the mask stuck to it (see red corner), but I can always cut that part off for next time. I don’t know what it’s called, but it’s designed specifically to remove masking fluid.
So, masking fluid + gouache + illustration board works great. The end. Questions?