Masking fluid can be a handy tool when painting with watercolors, because it allows you to keep certain areas of your paper white. You apply the masking fluid and paint over it, then when it's dry, remove the masking fluid and the area will be the color of the paper. Here's a link to several different brands of masking fluid: http://www.dickblick.com/categories/friskets/#maskingfluids
I've enjoyed experimenting with watercolor masking fluid so I thought I'd share an excellent tip I learned that might save your paintbrushes from certain destruction: Before you dip your brush in the masking fluid, moisten your paintbrush in water and then rub it against a bar of soap. With your bristles coated in a light film of soap, dip the brush into the masking fluid and apply it to your paper. If and when the masking fluid starts to harden on your brush, rinse the bristles thoroughly, re-apply the soap layer, dip the brush in masking fluid and continue creating your mask. Repeat as necessary until the mask is finished.
The soap trick is brilliant because it can save the bristles of your brush from hardening and becoming unusable. Before I discovered this trick, I ruined a few of my brushes because the masking fluid would dry fairly quickly into the bristles, which were then impossible to recondition. I always apply a layer of soap now before I use masking fluid.
Hope that helps! Does anyone else have any tips about using masking fluid, or experiences to share with using it?
Nice... I had one that I just dedicated to using in the fluid... and the rubber cement.
Alternatively you may put a few drops of liquid soap in your (small) water cup, and use this while doing your masking. Don't forget to change it afterwards! :)
i just use cotton buds.