Castaldo Gold rubber, does it have a shelf life?

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

That is rather an esoteric question. The quickest route for a reply is to phone Walsh head office. Dennis.

If its kept in a cold place it can last a long time not sure about six years though but I have used it thats maybe 4 years old with good results. If you can push it with tweezers for example it should leave a depression if its partly cured it will not do this