Can anyone tell me if this has a use by date on it? I got mine out the other day I've had it for about 3 years I used it on quite a complex drawing for a painting, after it dried I painted the area I had used it on, once the painted area was dry I found that the masking fluid wouldn't come off the paper, it just smeared all over the painting like chewing gum. It has ruined it and I am having to start again. I wondered if this has happened to anyone else.

Hello Bookworm! I don't wish to "teach grandmothers...etc", but was the paint properly dry?
If ther is any dampness in the paper at all, then the watercolour paper surface will be rubbed off.
Perhaps your problem is totally different than this; you say that the Masking Fluid was about 3 years old; did it smell worse that usual? Did you have to take a skin off the fluid?

Lets try and get to the bottom of this and see if we can discover the cause.

Steve Williams
RSC

Hi Bookworm, I'm a total amature at painting and the net, so I can only give you advice from my own experience! I did have the same problem as you with a new bottle from SAA Home Shop.
Thinking it was my in-experience and being a bloke, I then decided to read the instructions, there isn't any! So here is how I have solved the problem: (1) shake bottle really well for a good minute or two before using. (2) when leaving for a while, store upside down in your art box/draw and out of direct sunlight.
I have now had my bottle for approx 18 months and have not had any more problems.
I'm not saying this will work for everyone, but it worked for me.