I have just come in and gone straight to my shed to check on the casting from yesterday, it has gone off, but i also left a small amount in a tub with some of the Liberon oil in it which has also gone off? So not really sure as to why my two attempts with the pot is still runny. 
My next test will be to mix a couple of colours of the Liberon oil, and leave these overnight without going into the pot. Confused!!! 