Charcoal Making Log and Results

Test one 6-28-98
indirect "retort" method - moderately successful

Materials:

Furnace: 55 gal drum with lid cut out and a 12" wide by 10" high opening in the side at the bottom. Holes were burned about 8" up on the sides to put two 3/8" electric fence rods in for the retort to rest on. The idea was to be able to pull the rods out at the end of the burn and allow the retort to settle in the ashes to exclude air.

Retort: 16 gal oil drum with sealable lid. 6, 3/8" holes were burned in the bottom with a torch to allow gasses to escape.

Wood: 51.5# of air dried chunks (+/- 20% EMC not measured). Mostly hickory ranging up to 3" thick.

Heat source: hardwood slabs and bark in bottom and around sides. Newspaper and burnt motor oil as accelerants.

Misc: Welders gloves, shovel, platform scales,

Conditions: overcast, spitting rain occasionally. temp about 80 deg.F breezy with variable winds 8-12 mph

Procedure

2:40 started fire. Rods started to soften and bend within 10 minutes allowing retort to settle against one side.

3:00 (+20 min) After the fire was going good, I placed two rods across the top of the furnace barrel and positioned the cut-off top to hold heat in yet allow good draft.

3:30 (+50 min) Roaring sound as gasses burned off through holes in bottom of retort and around leaks in top.

3:40 (+1 hr.) No smoke - nothing but heat.

3:45 (+1 hr. 5 min) Tried to pull rods to allow drum bottom to settle in ashes to seal but they had melted too much to pull out. Fire mostly burned to coals.

3:50 (+1 hr. 10 min.) Outgassing stopped rather abruptly.

4:00 (+1hr. 20 min.) Carefully dumped over burn barrel to remove retort. Could hear charcoal clinking inside. Retort was fairly heavy (not a good sign). Set retort upright in dirt and packed dirt around base to exclude air. Left to cool.

7:00 (+4hrs. 20 min.) Retort cool to the touch. removed top. Contents had not settled much. Smaller pieces and the outside of larger pieces had become charcoal; larger pieces were still brown indicating incomplete conversion.

Results: The burn was stopped too soon yielding about a five gallon bucket of good charcoal and a lot of charred chunks of wood. Possibly the fire had cooled some so that the retort stopped outgassing and I thought the burn was complete. There was no sign of ash or any indication of flame in the retort.

Test #2 7-7-98
Indirect "retort" method - highly successful

Methods and materials:

As above except as noted.

Wood: 56# of 2 yr. old hardwood (mostly hickory) air dried to about 29% EMC.

Used 1/2" square hardened rod to hold up retort.

Conditions: 80_ F. light wind.

Procedure:

2:35 (start) lit fire with newspaper and some burnt motor oil.

3:10 (+35 min.) Outgassing starts. Added enough wood during the burn to keep temp up.

5:00 (+2 hrs 25min.) Outgassing about complete. Pulled rods to allow can bottom to settle in coals and ashes sealing holes.

6:00 (+3 hrs 25 min.) Lifted retort can - feels light indicating a complete burn. To ensure an oxygen-free condition and to facilitate faster cooling, I removed the retort from the furnace barrel and placed it on dirt, pulling dirt up around the bottom.

7:35 (+ 5 hrs.) Can cool enough to handle. Opened top and found the results of a good burn. Volume had decreased by about 1/3 and all of the wood appeared to have converted to charcoal.

Results: 56# of wood yielded 17 1/2# charcoal or 32% by weight. This is very good as most direct burns result in 25% at the best. I got over 2 1/2 five gallon buckets of good lump and only one large (4"X6") chunk showed signs of incomplete conversion with some brown in the center.

Charcoal Making at Home

From Dan’s Blurbs: Barbecue 101 Part II : The Fuel Published in Pleasant Living March-April ’07