Processing real dirt

As scenery progressed I ran out of dirt and needed a lot more. I use real dirt that I dig it up and process at home. The process is described here, and must be done outdoors so nice weather is required. 

So, in March I dug some up from my "secret place" and baked it in the oven at 350 for an hour. Some people skip this step but I can't understand why. I certainly wouldn't want living organisms growing on my layout. I used cheap disposable aluminum pans from the dollar store for this. Dirt is heavy, so set them on a cookie sheet for support.

Because of the uncooperative weather we had, the dirt sat for nearly four months until a nice weekend came along in late June when I could use three different sized sieves to filter it. You need to scrape the blobs of dirt against the screen to grind them into a powder, while tossing the actual rocks out. This part absolutely needs to be done outdoors as it makes a mess and dirt blows everywhere, and the fine dirt dust creates a haze that fills the air. Don't do it when it is windy either.

My sieves are small but adequate for the job. I would love to find appropriately sized mesh screen and build some frames out of wood to increase the amount I can process at once, but I haven't found a place that sells small quantities of wire mesh. Something like this, with much finer mesh, would be great.

The result is superfine dirt, and then essentially three sizes of rocks (which might include of balls of dirt that didn't break up during the sifting process). I store it all in cheap containers from the dollar store. 

I don't use the rocks much, but I use a lot of the dirt as that is the base layer of my scenery. And now that my supply has been refilled, I can work on some more scenery projects.