I recently purchased some Castaldo Gold from HS Walsh and it hasn't vulcanised properly. I made a 6 layer mould with it and two layers seperated when I removed the rubber from the mould. I have been using other rubbers with smlilar vulcanising temps so I know my equipment is ok. The raw Gold rubber is hard to the touch unlike other rubbers that I have used, I suspect it may have exceeded its shelf life but cant find anything marked on the packaging. How can I tell if the rubber is ok?

Cheers

Bob G