Thining masking fluids

FYI: Masking fluid also known as drawing gum or liquid frisket is used to reserve whites when painting with watercolor.

Question: When masking fluid gets thick how can I thin it so it can be used again?

Susie's Replay: Unfortunately there is not a simple answer to this problem. I find than most masking fluids have a relatively short shelf life once they have been opened and exposed to air. Most manufacturers state the shelf life for masking fluid is +/- 12 months.
Depending on the formula used to make the masking fluid (most are made of latex with ammonia added as a preservative) you might try adding a drop or two of pure ammonia (not ammonia with soap added.) Sometimes a drop of water will work, but not always. Test first! Try thinning a small amount in a separate container so as not to destroy the whole bottle of masking.
My best advice is its better to be safe than sorry..... if in doubt as to whether using old masking will work as it is intended don't risk it on an important project. If you are just experimenting and playing with the paint then you can afford to take a risk.
If possible check with the manufacturer of your brand to see what they recommend.

Thanks for your question. I'd be interested to know if you find out there's a better solution.
SUSIE