Just for discussions sake...what type of silicone were you using and how much tint did you add? Honestly, it seems strange to me that the silicone isn't setting. Silicone, in my experience, has been pretty forgiving and has set up pretty well in a lot of different conditions and tints. I've found it to be WAY less finicky than urethane...which takes forever and a day to fully cure. The only time I've had silicone not set correctly was during a test in which I was trying to make a platinum cure silicone cast with a tin cure silicone mold...they didn't like each other...which is why I was testing it...really glad I did too.