Make sure and mark the jar with the correct name of the tomato!!! I try to learn from my mistakes. LOL
The coffee filter allows the mixture to breath and bacteria to grow this is what devolves the jell like membrane that surrounds the seed, the major benefit of using the coffee filter is it keeps unwanted bugs out. Your germination rate goes way up when fermenting your seeds in methods like this.
I next set the container with the seed mixture outside for five to seven days. I don't suggest letting them ferment any longer than this it tends to lower the germination rate. Also setting them outside is recommended because it can get a bit smelly.
After the five to seven day period a mold growth will appear on the top of your seed mix. This is a good thing it is telling us the bacteria has done its job dissolving that jell like membrane. This will make it easier for the seed to sprout this spring. Your almost done all you have to do now is clean up the seed mix. I first try to fish out the mold growth (this is a yucky job) and discard it. Next I wash and strain the seed until it is clean. I use a fine wire strainer to help me clean and strain. Clean them several times.
Last thing to do is see if you have any seeds that float, if so discard any seed or seeds that float. Next just lay out a paper plate set your seed on it set it in a warm dry place for at least two weeks to dry. I stir mine up every few days. Then pack it up for next years tomato seeds you can use envelopes or little bags to store them in.
Storage it is important so keep them in them cool and dry and out of light.
During the winter I will test a few of each variety so I can do germination tests to make sure I have a good viable seed.
This is so easy to do give it a try.