Originally Posted by
HighUintas
With my large number of frequent posts, I'm not surprised that you missed it or lost it!
I'm using wood from the Paulownia tree in my backyard. I trimmed it a bit ago and used branches ranging from 1 in to 2 in in diameter. I cleaned off all the bark, dried them out completely in my toaster oven set to 150 Fahrenheit on convection, and split them into pieces that were roughly half inch by half inch.
I did not clean out the flaky pith material from the center of the branch, nor did I cut out any bark seams from offshooting branches. I don't recall seeing any bark seems running through the pieces I put in there, but it's possible there were a couple. I think the wood was pretty darn clean, other than the centerpieth material.
I packed it into my one gallon paint can, fairly snug but still loose enough to rattle when shaking the can around. I put it on my propane burner, which has a 10-in ring filled with a whole lot of tiny nozzles all the way to the center, so it does produce very even heat throughout that 10-in circle. I had the paint can on its side with a 3/8 inch hole for venting, and a grill thermometer installed as well. I also had a stainless steel stock pot sat over the top of the paint can on the burner to create an oven to help heat it more evenly. I still turned the paint can 5 to 10 minutes to help heat the can evenly.
From the point of starting to heat the can, to the point that I turn the flame off and taped the hole, was 45 minutes. There was a very lazy yellow flame coming from the hole that did not want to stay lit when I decided to shut the burner off. The thermometer finally jumped up between 600 and 650 degrees Fahrenheit in the last several minutes of heating it. It read lower most of the time.
I also have some powder made from rosebud brand cedar horse bedding chips, and a cedar picket from Lowe's. I cooked the chips in my one gallon can as a test prior to doing the polonia. That test was a little less controlled, but the temperature hit 600° right as I turned the flame off.
The cedar picket was charred in a court size paint can, on a different propane burner that is less powerful and I had the flame turned about as low as it would go. The cedar picket took about an hour and a half to finish. When I pulled that charcoal out of the can, one end of it was all black of course, and the other end of the wood was a very dark brown. The black and of the charcoal sticks was on the lid side where I had the ventil facing down and burning, so it got more heat than the other end of the can. I didn't have a thermometer in that small can, but I am guessing the temperature was much lower than the one gallon cans, since it was dark brown on the other end.
With burn tests on paper, all three powders left a yellow halo around the burn area and it seemed that the cedar chips left slightly more black carbon fouling on the paper than the polonia, and the cedar picket left even more black carbon fouling on the paper then the chips. But, the cedar picket powder was only meal and had not been pressed and dried yet.
Because they were three different wood sources, I can't draw this conclusion with certainty, but it seems possible that the lower charring temperature of those woods could be causing them to burn dirtier