Mark, sorry I missed this!! What size is the finest powder you use? That's what I would go with. I have a shop vac with as fine a filter as I could find then I put a cloth filter over that, I spilled some white powder, sucked it up with the vac and blew it out the exhaust, so much for clean up.LOL I would go with a 1 micron filter or smaller if that's what you want to do. The other option is to put a box or plenum behind the exhaust to slow down the air and let the powder drop out.
Again, I apologize for the tardy answer. I know I haven't been around much, I've done very little pouring the last few years. I'm going to have my 3rd surgery in 4 years this summer, my left wrist is bone on bone and it's sore as heck. I see the surgeon June 1st, I'll go from there.
Rodney