JoAnn,
Some of the stalks that go very dry will shed their seed into the bottom of the bag and have very little chaff. If you let the seed stalks dry in the bags until October, most of the seed capsules will have fallen out of the capsules. Others require more of a squeeze to release their seed. I give the bag a gentle crush and then decant the bag over a sheet of white paper that is lying flat but has a fold in the middle. You can hand pick out the bigger pieces of chaff at that point. I then fold the paper and decant the seeds and small bits of chaff into ungummed glassine envelopes. Fold these envelopes and place that envelope in a coin envelope that i seal. Semp seed is so fine that it can leak out unless you do the double envelope technique. I then put the envelopes in a Ziplock bag and store them in the crisper until late February. They are then planted in pots in a good potting mix.
Ed Skrocki used a series of sieves to get the seed very clean but neither Bill Nixon or I found that the chaff significantly affected germination.
Kevin
