Lets not wax too poetic about the smoke exploding inside the kiln. Remember there is a fire inside the kiln. The smoke contains the creosote that will/could condense and is a nasty carcinogen. This is why the respirators are in use. Could be burned off perhaps rather than let loose on mother earths atmosphere. Believe smoke to be the VOC's (volatile organic compounds)that are so nasty what you want is pure carbon. Heat drives off the VOC's and leaves behind carbon or coal if you like.

For many things like grilling/forging/melting the VOC's interfere with what you want which is a clean/hot fire.

I just made a small batch- a couple of pounds- of softwood charcoal yesterday using bricks shaped in a U to hold fuel and foil over. Went to check half way through , still nasty yellow smoke being emitted, and it burst into flames as soon as I opened it just a bit.

Why softwood charcoal? I am going to make a bit of black powder so I can work with my grandsons in making rockets etc. Believe the softwood gives more surface area/carbon content making the oxidation faster with the nitrate. Yes will be careful. Thanks.