The times I've used fine ground I put a second screen in the bottom of the crucible and another about a quarter of the way down from the top, making a smaller chamber for the loose weed. That helps protect the small inlet holes in the heating chamber as well as the coarser screen in the mouthpiece. The herb gets cooked just fine. Another tip-at some point herbalAire changed their bags. They're a little thicker than the Toppits bags I like to use. Toppits bags, when overfilled, will burst, but you can hear the crinkling sound as the bag gets full, so it's not a big deal if you're in the room. HerbalAire bags will fill to a certain point and then leak, like a safety valve. So if you're not paying attention during a fill, you may find that nearly all the vapor has leaked out and you just have a bag of mostly air left. This results in vapor loss but you don't lose the bag. I can't be sure your bags are like this, but I bought some extras about 6 mos. ago (mainly for the connectors-to make more Toppits bags of different sizes) and that's what I got.