Becky - Please let us know how it goes. I think that I used 1/4 inch screen when I tried that method. I also tried an old plastic pasta type strainer with much smaller holes but everything stuck to it and the holes were quickly plugged up. Maybe there is a happy medium between drying them and not killing all of the living organisms in there. I've read articles from some of the experts in the field and they always say that the castings are living and they should be kept moist and aerated ; which makes sense to me.
I wanted to mention that I have been keeping my bin in our garage. It is not heated and has a regular non insulated door but the worms have been fine this winter. We had a few mornings in the teens but all was well. I keep several inches of shredded dry paper on top and that seems to help insulate and wick away any extra moisture. Also, I always keep the lid just slightly off the bin. Every time the lid gets snapped on tight (my 6 year old loves to help), I get worms trying to escape. I think it just gets too moist inside there. I do have air holes around the bin and drainage at the bottom; although, I don't ever have the leachate drain from the bottom.
Best of luck !!
