If the seeds are grown in an area where there are diseases people often add a short bleach rinse for 2-3 min as a last step. If you can search it out, here at T'vll, there is a thread on seed saving methods. Probably more than one
Carolyn said that about 15% water can be added to seeds if not wet enough. I did not get good results using water so I added juice from other tomatoes if the seeds were too dry.
Here's Tatiana's page on it.
http://tatianastomatobase.com/wiki/A...g_Fermentation