Hello, is there any sort of lettering I can use that water paint will not stick to? By this I mean I want to place some letters on a page and be able to paint over these letters but for the paint to come straight off. Any way of doing this? Is there some sort of plastic letters that would work?
To be able to answer your question, I really should know more about what you are trying to accomplish and how you plan on using the work.
From your question, I believe you are trying to produce a colorful watercolor area as a background for white lettering. It sounds like you are trying to find pre-formed letters that can act as a mask for the lettering—producing white letters. To my knowlege, there is nothing exactly like that available.
You may be able to make an accurate pencil drawing of the lettering and mask the letters with masking fluid. In that case, I would advise a paper with only a slight texture. Also, you might consider using white transfer type applied to the prepainted watercolor background area.
Here is one long shot you might experiment with. I have a vague recollection of the use of transfer type as a mask for marker renderings. This goes way back but some ad designers were using transfer type to simulate reverse (white) type in comprehensive layouts. In that case the transfer type (black or white) was applied to the working surface. Then, the background area was rendered (right over the letters) and the lettering was removed by pealing it up with a strip of magic tape. This required a fairly hard, smooth working surface. If it worked with markers, it might work with watercolor under some conditions. It is worth a try—but I wouldn't bet a lot of money on it.
If your artwork will eventually be used as a printed piece, such as a poster, there are many ways to accomplish this through the conventional methods of producing reverse type. Also, if it is to be used for reproduction, there are several computer graphics applications that can produce what you are looking for as a pretty basic effect.
I have many years of graphic art and watercolor experience. I can help you more if I know more about what you are trying to accomplish.