If you mean after applying the silver nitrate, my experience has been only a few hours. I once tried coating about noon, printing a few, then trying again the next morning. The overnight prints were much slower and had much less contrast.
I did some salt printing several years ago but don't know the answer to your question.
However, it has been my experience that most coated emulsions, including VDB, kallitype, pt./pd. will last much longer if stored in a zip lock bag and placed in the refrigerator or freezer. I made some pt/pd prints a few years ago from paper that was stored in the refrigerator for about a week and they came out very well.
Originally Posted by Falkenberg
I am planning on doing a batch of papers for saltprinting and was wondering how long thy will keep when they are sensitized.