Yeah, I see that it says water-based. I actually found a bottle that I already had.

Have you tried thinning it? Can you use water?

See, I ask because Green Stuff World sell a thinner for those paints. And it isn't water. Which is why I ask what you can thin it with.  I don't want to buy their thinner if I can use water, or one of the many thinners I already have.