...so I try 1/4 cup variations in the water, weight the lime in a scale like I would a glaze.

If it cracks is that mostly from drying to fast. what if I spritzed it with water as I worked.....not wet....but not drying either...think it would make a difference?

I have been doing a few test pieces on plaster with acrylic colour washes....don't laugh....I thought the feel of the brush on the plaster would be about the same in a general way. ???? What do you think?