I called Aurastone tech support about the crete not bonding to some area of the tile back splash....they said there was only 1 reason that it would not bond - it must not have been cleaned thoroughly in those spots. The said to sand off the areas that didn't bond, clean it with Acetone with a cotton swab or rag and then let it dry and re-crete over the top and feather it in with the other layer that I had already done. I did all that and it worked. What did I learn from this extra work? Do your own prep work or train someone to do it correctly - don't assume your client has the training to know exactly what to do. Even if it does save you time, in the long run - it really doesn't if you have to re-do.
That's all I know today....tomorrow could be a whole new learning experience.
PS..I order a new kind of paint today - chalk paint! It's not chalkboard paint - it's chalk paint. It claims that you can paint it over an old piece of furniture without sanding and deglossing the piece. It will bond right to the varnish top coat or whatever you are putting it on. I will let you know once I use it if it does what it says. (I know, forever the skeptic...) If it does - OMG that would save tons of time in prep and sanding!! I think that you are limited right now to certain colors but maybe someday they will have a untinted base you can tint yourself???