Don't do this

[TXCraig1]

I threw a good sized piece of wood on the coal pile right before I closed up the WFO. I thought I was being clever - that it would make a piece of charcoal that would make it east for me to light the oven the next time. It did make a piece of charcoal, but it made more than that. The tar and creosote released condensed on the uninsulated door - mostly near the bottom. I didn't notice it until I set the door down on the mantle. It was really hard to get this stuff off. It's thick and stickier than you can imagine. It laughed at my citrus degreaser. I ended up burning it of the door with my cactus burner.

[Pete-zza]

Craig,

Can you secure something to the inside of the door that you can later remove and discard?

Peter

[TXCraig1]

Craig,

Can you secure something to the inside of the door that you can later remove and discard?

Peter

I don't know. I'd be worried that the tar would drip down onto the stone floor if it was inside the door. I was lucky that the door sits just outside the oven so it dripped onto the metal part of the hearth. It was really really hard to clean off, and there still is a dark mark, but it missed the floor.

A well insulated door would probably solve the problem, however for me, I think it's just probably best not to do it.

CL

[trosenberg]

Was it a piece of hardwood that released that much creosote?

[TXCraig1]

Was it a piece of hardwood that released that much creosote?

Yes. Post oak.

[dellavecchia]

I believe you should never have a closed door with an active flame. There is the possibility of an explosion. At least that is what I have read.

John

[shuboyje]

With the door closed like that you are going to end up with a pyrolysis reaction making the charcoal that was the goal.  The products of pyrolysis will be flammable gasses, Tars and charcoal.  That is actually why this method of wood gas production is not used to run internal combustion engines, the tars quickly clog them.  A wood gasifier adds a super heated reduction zone that breaks down the tars enabling the gas to be burned in an engine.

So yes there was a potentially explosive situation here but with the small amount of wood and an oven door which is not completely air tight I doubt Craig or his Acunto where ever at much risk.

[Jet_deck]

Ok, I'll nibble.  How is there a risk of explosion?

[Tscarborough]

Your door just has to be tight and insulated, no explosion, I make some every time I fire it.

[shuboyje]

If the oven's mass is hot enough to support the pyrolysis reaction needed to make charcoal then that same pyrolysis is creating flammable gas.  If the door was airtight you would have a enclosed space full of flammable gases.  I think it goes without saying that an enclosed space full of flammable gas is a potentially explosive environment.

[TXCraig1]

If the oven's mass is hot enough to support the pyrolysis reaction needed to make charcoal then that same pyrolysis is creating flammable gas.  If the door was airtight you would have a enclosed space full of flammable gases.  I think it goes without saying that an enclosed space full of flammable gas is a potentially explosive environment.

An airspace full of flammable gas is not an explosion hazard. You need oxygen too. It's surprisingly difficult to get the mixture just right.

[Tscarborough]

I'm not saying it won't explode, I am saying it is possible but not likely.  You could certainly make it explode though. 

[shuboyje]

I agree as I already said there was no danger there.  I was just trying to answer the question of how this could be viewed as hazardous.

[Tscarborough]

As I have always told my kids, usually when they ask about a pony for Christmas or something, "It is possible, but not likely", "Monkeys flying out of my butt is possible, but not likely".