Hi Tom,
MEKP is not the correct type of catalyst for CS25 (or indeed any Silicone). MEKP is a catalyst for Polyester and Vinylester Resins and so if you have used MEKP then unfortunately, the silicone won't cure at all. You need the CS25 Silicone Catalyst for the CS25 Silicone.
Sorry to be the bearer of bad news.