concrete; my cake form

My idea here was to make a form that I could reuse like a sand cake form; when you turn it over and bang it a bit with your plastic spade -  you get your cake out. I wanted to have this form to make different tests and variations in concrete in my studio.  After making it I gave it all sorts of love, care and attention,  I waited three days for it to dry before using it.  But that wasn't enough ...  I knew I was pushing it...  ... the plaster hadn't dried enough  ... and because of that the shellac (lacquer) didn't stick properly  ... and the plaster sucked all the water out of the concrete over night  ... and I got a "nice crack".  (This might also mean that the concrete got stuck to the plaster and I can't reuse my form, but I won't know until I have the time to go to my studio in two weeks) Shit. Patience is a virtue. Hopefully I'll not make the same mistake again ....