i`ve been using some T20 silicone rubber to do a rather large mould, but i don`t think i`ve used enough catalyst, it`s been 24 hours, it has cured only slightly, i just want to know if i leave it long enough will it cure?
Sounds like not enough catalyst to me. Eventually it will cure, it may take up to a week but eventually it will. Once the mold is stiff to a finger pressed in it you should be ok. You should be able to tell the difference between an uncured mold and a cured mold by pressing your finger in it. the stiffer it is the better.
I have also heard that some peoples molds never cure with a lack of catalyst. Personally my have all cured eventually. If yours doesn't by a week then it may be trashed.