painting

I'm experimenting with paints. I've found that Golden heavy body paints are thick and useful for texture.

But, liquitex soft body paints feel practically like ink in that I can easily draw lines using a liner brush.

Just adding water to the thick paint doesn't achieve the same thing. Is there some sort of material I can add to thick paint to achieve the same effect so I don't need to stock up on multiple types of every color?