need some advice on how to keep my daughter and i's head from cracking!!!air dry clay? Answered

I can't personally tell you any particular information, but I can tell you from my second-hand experience (my sister was a potter) that all clay has a fair percentage of shrinkage when dried, and more so when fired.  The amount depends on the type of clay, but it ranges anywhere from 2-12% from what I've seen.  Types of clay that have the least shrinkage usually have smaller particles (like porcelain) and are extremely difficult to work with; crafting clay like you get from most hobby stores is similar to earthenware, which draws up 10% or more on average.

Without knowing specifically what you're trying to accomplish, the only thing I can tell you is you will have an impossible time making clay masks in this fashion.  As others have suggested, you will have far better success with papier-mache or plaster casting.

Agreed with all the others, make it thinner:

If you can dry it in a humid environment, so that it drys as slowly as possible.  Put it in a box with wet paper towels wadded in the corner. 

Go THINNER, not thicker. Its cracking because the outer skin is drying before the interior. Thinner is better. 

What's the aim ? Maybe this isn't the best way of doing what you want, in the time you have ? 

Personally, I'd try papier-mache - using tissue paper as the paper and slightly diluted woodglue as the glue. Again, thick sections are bad - they won't crack, but they won't dry either....

Steve

2 possibilities:
- the coat is too thick and/ or
- the coat dried too quickly

i suggest you peal it off the head by hand and.use sandpaper  (grit size P200 or more) or a diluent, if necessary..
you should spray/ paint it in long and equal layers otherwise it will crack again.

If you'r in a hurry, you should peal or sandpaper only edges of cracks and reaplly the coat (on cracks only).

Take your time..