The most obvious reason to use masking fluid is it acts like a little stop sign to keep paint from getting on areas where you don’t want it. Meaning, that if you have masking down on an area and it’s dry, paint can’t go there. It literally stops it in its tracks. You never have to worry about accidentally painting over a place you wanted to keep white, no matter how small.
A lot of times there will be very small areas that you want to keep white and trying to paint around these can be very stressful and time consuming and forget about trying to do this with wet-on-wet!
A few warnings, though.
1. Don’t use any of your good brushes for masking fluid! Masking fluid will ruin your brushes. You’ll never be able to get it out completely. I use brushes that are damaged for masking fluid. You can buy a cheap brush or two for this purpose. For pinhead size whites, I like to use the head of a needle.
2. Don’t leave the masking fluid on too long. Masking fluid has been known to stain paper when left on too long, so if you want a clean white space, just put it on in preparation for painting the area you’re going to be working on in that session and peel it off once the paint is dry, which brings me to my last warning. Also, to avoid staining, try not to have masking fluid on an area more than once, especially if you’re using it to preserve that area as white.
3. Don’t start painting until your masking fluid is dry and don’t take the masking fluid off until your paint is dry. If you do try to paint while your masking fluid is wet, or remove masking fluid while your paint is wet, you’ll have a mess on your hands.
You can buy special tools to remove masking fluid, but I just use my finger and I’ve never had a problem. I just rub it gently until it comes loose and either peel it or keep rubbing until it comes off completely.
Besides using it to preserve whites, you can also use masking fluid to keep a certain color of small areas that you want to be a different color. For example, in my latest painting, I wanted the main part of the grass to be green, but I wanted there to be subtle bits of yellow in it. I used masking fluid to block off the parts that I wanted to stay yellow while I was painting my green on.
I use Winsor and Newton's masking fluid. You get yourself some at this link. If you buy from that link, I get a small percentage.
Watch the video below to see the steps I described above in action.
Painter of portraits and wildlife