|Tomatoes drying on the roof. Fine seed-screen aft.|
I made up a couple of wooden frames and scrounged around for various sizes of plastic mesh. Lettuce is a particular challenging when it comes to Right Sizing a screen. 1mm mesh is just a tad too small, but I've been unable to find anything with a (say) 1½ or 2mm gap.
Cleaning Carrot seed has proved to be too hard on the plastic mesh, and tore gaping holes in the mesh, so I swapped it for a metal Mosquito mesh - also about a 1mm gap. But even that can't take the pace when it comes to Carrots. I clean the Carrot seed heads by rubbing them (gently!) around on the mesh, and the seed falls through, mostly leaving the burs and stalks behind. I quick threshing in the breeze gets rid of the dust, and Carrot seed is done.
I find it funny that people who have never saved their own Carrot seed don't realise that the seeds are prickly. They've only ever experienced machine-cleaned Carrot seed which has had the burs rubbed of in the process. I was there, too, once upon a time. In fact when I tried to send some seed to a friend in Australia some years ago, they never arrived. Instead he received a short note from the Aussie customs to say that the seed was "contaminated with unknown weed seed" and had been burned. I guess we can't really expect customs officials to be seed-recognition experts, too.
Like everything else in a self-sufficient permaculture setup, we aim for "every design element to support multiple functions," and so it is, too, with the seed-screens! We're presently using a couple of the screens to sun-dry our surplus Tomatoes on the roof during hot days. A wide mesh supports the Tomatoes, keeping them off the roof, and the fine mesh forms a lid to keep bugs off while the Tomatoes dry. It takes about 2 or 2½ good, hot days around this time of year to get the Tomatoes good and leathery, though we're experimenting with slightly thicker slices, so this batch might take a little longer.