AI have two 12" squares. One cracked when I was flipping it. It's not cracked all the way through. The other layer is fine. Where would you put the cracked layer? On bottom or on top?

I would put it on the bottom bc you can "glue" it back together and then using a level thingy (I can't remember what they are called) you can make sure the top layer is completely level all way round which would be difficult with a cracked layer.

AThanks Claire138! :) That's kinda what I was thinking as well.

You're welcome, good luck!

Yeah, what Clair138 said.  That's what I have done and didn't have any problems.