If you can find long, thin shreds, those give the best aeration. I only found those once!
But then I found bark "nuggets" at Lowes. Those were so clean and free from powder that I can use almost everything in the "small" bag. Medium and coarse are bigger than I need. I now keep anything that won't pass 1/4", and I would consider a pass with 1/8" hardware cloth when I buy some.
I used to have so many fine bark fibers even after screening that I didn't want any peat at all. But now I have a very coarse, grainy bucket of nuggets, and do plan to add some commercial peaty stuff, like 10-20%.
I also found 1/3" hardware cloth from McMaster-Car. The lightweight "easy to form" non-woven kind is strong enough when supported by something. And it only costs $1.23 per sq. foot, not $15! (Avoid stainless and heavier woven steel cloth, due to price.)
These photos show chopped juniper branches as I screened them so I could put the bigger pieces through my lawn mower again.
I like to shovel and screen from one wheelbarrow to another to reduce bending. I also keep a clean tarp on the driveway so I can flip chunks off the shelving down to gorund level without getting them dirty.
