Masking out areas of a painting can offer interesting options and help create unusual styles. One of the popular methods for masking an area of a painting is by using a product referred to as masking fluid or sometimes called frisket or even sometimes misket.
The masking fluid is most commonly used by water colour painters and it's basic function is to mask areas of the paper that the water colour painter wanted to maintain as white. They would paint an area with the fluid and it would protect that area of the paper from any subsequent colour applications that were applied once the masking fluid has dried. Once the painting is complete the artist would remove the masking fluid - and voila ! nice crisp white paper below. But you can take the idea and run with it!
Above is Pebeo masking fluid - I've used it frequently with great success! I find that some of the masking fluid dry up on the shelf at the art supply shop but this one always seems to stay fluid. Make sure to tilt the bottle before you buy it to make sure that you aren't buying a dud! I've seen these turn into a bottle of solid rubber on more than one occasion
And lo & behold it's not just for water colour painters! Acrylic painters can enjoy masking paintings with masking fluid as well and it removes quite well from acrylic - some say better than it removes from paper. Please do a test to ensure it will work well no matter what surface and paints you are using.
Masking fluid is often tinted so that you can better see where it has been applied. A strange disadvatage of this is that this can effect the way you instinctively choose and use colour on thr rest of your painting. As a result there are some artists who remove the dried fluid once the painting is complete only to discover that white of the paper now looks way too white. You can always paint over these areas with a colour similar to the tinted fluid if thats the case.
Above is one of my favourite masking products - The MasquePen - because it's got the fluid and the applicator all-in-one and it applies the fluid in super fine lines when you need detail. Don't use your best brushes to apply masking fluid - if it dries on the brush at all it can become impossible to wash out. Masking fluid is a rubber-latex formula and can really gum up your brushes once it begins to dry. Some artists dip their brush in soapy water to help form a barrier between the brush and the masking fluid to further aid in protecting the brush.
The way to remove dried masking fluid is by peeling it off or using a rubber cement pick-up that looks like this:
*Another note about removal: you'll need to remove the masking fluid as soon as possible other wise it can become impossible to remove.