The clay that Perry Aldridge sells "swells" in water so a little goes a long way. For a 16 oz bottle of water, I'd start with about a tablespoon of clay. Put the clay in the bottle, add the water and let it set for a while and then shake, shake, shake. If it's not thick enough, add more clay.

I use Aztec Secret clay powder topically for masks and I used to make it up fresh every time, then I found Perry's hydrating instructions. I put some clay powder (1tbs) in a small container (1oz jar) and then added water. I left it alone (lid on) for a while, maybe an hour and then discovered to my delight that I had a lovely batch of wet clay ready to apply.

I haven't got around to trying Perry's clay, but I've heard good things about it.

iolite