I'm spending quite a bit of time cleaning seeds for sowing next year. I've been using the two recommended methods of sieving and winnowing. I've also been using static electricity to separate the chaff. I use a large plastic soup or yogurt pot. You have to rub the top of the pot inside in a circular motion an inch or two above the seed until you get enough static for the chaff to stick to it when you lightly agitate the pot. It helps to hold the pot right near the bottom with one hand because if you touch the top on the outside it disperses the charge. Once you've got the charge going, a continuous stream of chaff lifts each time you stroke the last lot away (upward and over the side). You don't want too much of a static field or it will lift fine (like lavender) or fibrous seeds too, so give it a rest every so often - also, I have even had seeds fly clean out of the pot if I get too enthusiastic! It helps to have either a cat sitting on your lap, a nylon fiber carpet or a computer screen nearby, but you don't have to have these in order to sucseed (excuse pun).