As long as you have followed the guidelines and added the correct amount of liquid this shouldn’t happen. If it does, you can simply add a little more Jesmonite liquid to the mixture and it should loosen it up. Just add about a teaspoon of liquid to start with and see how you go.

If you have left your mixture for some time, it might have begun to set and you will need to add more liquid and start to pour into your mould before it completely sets.