Fluid bed filter test video
I wanted to test a bunch of fluid bed filter mediums so I figured I'd video the results. I used coffee filter, newsprint, 20# printer paper, 30# printer paper, Tyvek (Post Office express mail envelope) and grocery bag. If you don't want to watch the video I'll tell you now that I think the grocery bag did the best, followed by 30# printer paper, then 20# printer paper. IMHO it's because their thickness is more uniform. The coffee filter and Tyvek had a lot of streaks of thick and thin areas and I think that caused un-uniform airflow.
One tip I forgot to mention is to shake the fluid bed a little after you get a good airflow going. I find that helps the powder settle down and move about more evenly.
Please feel free to recommend other filter mediums and I'll try to get them and test. I know there are some professional meshes available but from what I've seen they are very expensive and you have to buy a large quantity.
http://youtu.be/_WELQxrOr30