Why does (fire)wood burn better when split?

[beppington]

Just wondering. Some of my lazy friends put un-split logs on the fire & wonder why the fire just smolders.

I hit the piece with my maul, put it back on the fire, & now you have a good fire.

But ... why?

 

[MoKelly]

Smaller pieces of wood get hotter faster and therefore burn faster and better. The smaller the fireplace area the smaller the wood needs to be to get to the ideal temperature to burn properly.

MoKelly

 

[CTPhil]

In a wood stove there seems to be a benefit from draft-like air movement created by multiple pieces of wood.

 

[valley]

Wood has to get to 450 degrees to release the gases that burn. There are more gas containing resin in the inner wood that is exposed when split.

I have read: Wood doesn't burn. Volatile gases burn and are released when wood is heated to 450 degrees. When all the gases are burned what is left is Charcoal. Charcoal is flamable.

 

[beppington]

Smaller pieces of wood get hotter faster and therefore burn faster and better. The smaller the fireplace area the smaller the wood needs to be to get to the ideal temperature to burn properly.

MoKelly

Makes sense (my scenario is a camp fire BTW)

I thought it could be that the splitting action exposes torn fibers that burn easier & help the surface of the wood heat up faster ... vs the round exterior of a tree just under the bark which is usually smooth(er).

 

[brin]

Just wondering. Some of my lazy friends put un-split logs on the fire & wonder why the fire just smolders.

I hit the piece with my maul, put it back on the fire, & now you have a good fire.

But ... why?

I have never been able to master this , but my sainted Dad used to toss a whole Pine or Oak log on the back of the fire...I mean a big one 16 " dia or more and it would burn and burn...not smoke..Now this was on a bed of hot coals and he banked it somehow and it always worked for him..he would get the fires so hot it would run you out of the house...I have never been able to master the art...be he did....It was a masonry fireplace...:thumbsup:

 

[sailorman]

probably a combination of all mentioned and some not . I recommend you remind your friends wondering doesn 't matter when one is doing a camp fire for heat and or enjoyment . Suggest they just do it the way you have shown them it works better and get another beverage .

I add, split wood is also easier to stack, but since you said they are lazy they probably do stack either . Also a split wood exposes more perpendicular surface area to rising flame than does a cylindrical log .

side note : be careful as they may be pullin ' A Tom Sawyer / Huck fin white wash the fence routine. Just gettin ' ya to split the wood .

 

[Craig Clayton]

Wood has to get to 450 degrees to release the gases that burn. There are more gas containing resin in the inner wood that is exposed when split.

I have read: Wood doesn't burn. Volatile gases burn and are released when wood is heated to 450 degrees. When all the gases are burned what is left is Charcoal. Charcoal is flamable.

I would also like to add this observation to valleys statements in that a single piece of wood does not like to burn easily. It needs a feed back of heat to convert the wood to a gas so it can burn. When you put in split wood the pieces are smaller and the spacing is close to each other so each piece heats the opposite piece. The Big Old Round will burn on a bed of coals because the coals supply the heat to turn the Round into gas to burn.
I have had a single piece of wood burn in an EPA stove but it must be within 3/4 in of the refactory brick to bounce the heat back to make more gas to burn.

Craig Clayton

 

[SandburRanch]

Maybe, just possibly, with split wood there is more surface area exposed to the air that's needed for wood to burn.

 

[beppington]

probably a combination of all mentioned and some not . I recommend you remind your friends wondering doesn 't matter when one is doing a camp fire for heat and or enjoyment . Suggest they just do it the way you have shown them it works better and get another beverage .

I add, split wood is also easier to stack, but since you said they are lazy they probably do stack either . Also a split wood exposes more perpendicular surface area to rising flame than does a cylindrical log .

side note : be careful as they may be pullin ' A Tom Sawyer / Huck fin white wash the fence routine. Just gettin ' ya to split the wood .

Haha! Now that's funny!! ... as long as that's not what's happening

 

[Rocksprings]

Must be alot of bad weather out there and everyone is inside bored to death. :laughing::laughing:

 

[Larry Caldwell]

Must be alot of bad weather out there and everyone is inside bored to death. :laughing::laughing:

Yeah, 80 mph winds on the coast and 45 mph inland, with heavy rain. It's too dry this fall for any flooding yet, but the creeks may get a bit muddy. We haven't had a storm this strong since 2007. The rain's coming down at about 45 degrees right now, and the storm is just getting started.

As for rounds, there are two factors:

1) The bark and rings have evolved to preserve the tree's moisture. If only the end grain is exposed, the wood dries very slowly. It can take a round 2 or 3 years to dry to firewood. Splitting the wood destroys this natural barrier.

2) The same bark and ring structure has evolved to make the tree fire resistant. Splitting the wood destroys this natural barrier.

This can have advantages. If I want to hold a fire all night, I will put a couple large rounds in the stove, assured that I will have a nice bed of coals and maybe some charred but unburned wood in the morning.

 

[Rocksprings]

Yeah, 80 mph winds on the coast and 45 mph inland, with heavy rain. It's too dry this fall for any flooding yet, but the creeks may get a bit muddy. We haven't had a storm this strong since 2007. The rain's coming down at about 45 degrees right now, and the storm is just getting started.

As for rounds, there are two factors:

1) The bark and rings have evolved to preserve the tree's moisture. If only the end grain is exposed, the wood dries very slowly. It can take a round 2 or 3 years to dry to firewood. Splitting the wood destroys this natural barrier.

2) The same bark and ring structure has evolved to make the tree fire resistant. Splitting the wood destroys this natural barrier.

This can have advantages. If I want to hold a fire all night, I will put a couple large rounds in the stove, assured that I will have a nice bed of coals and maybe some charred but unburned wood in the morning.

That clears up everything, Thanks

 

[valley]

Well, that was fun! The stove is going constantly and all the things we just mentioned are at play in the fire box. I'm enjoying keeping the fire going.
Just put a thermometer in the stove pipe, that does help. We just put one [stove] in our other place. I'm looking forward to putting the final touches on the chimney and stove tomorrow, feeding the stove and watching the fire preferably with a large brandy.

 

[PossumHound]

I'll try to keep this fairly short as I know y'all don't want to know everything my college perfessor taught me about chemical reactions. Essentially, you all have part of the story right.

Fire is just a chemical reaction plain and simple. Every chemical reaction proceeds at a rate proportional to a) surface area of reactants, b) concentration of reactants, c) temperature of reaction chamber. If in an enclosed, airtight reaction chamber fire will also burn faster as the pressure increases, but in most wood fires that is not a consideration. Splitting increases the surface area as already noted. Also already noted, increased air flow increases the rate as more oxygen is transported into the reaction. Split wood tends increase the draft in limited areas, i.e. between the pieces of wood, thus more oxygen there. No matter what the fuel, fire usually needs to be kindled by some mechanism to reach the reaction temperature (kindling temp) of any given fuel; this is the amount of energy needed to reach the point where the fire releases enough heat on its own to continue the reaction until one of the needed reactants is exhausted.

Rockfish noted an important consideration I left out, but he's absolutely right.

Lesson over, hope I made it clear enough.

PH

 

[Egon]

The larger pieces of wood will also form a carbon layer on the outside preventing oxegen from getting to the wood vapours.

 

[greasemonkeyok]

In my experience Larry has a good point. The proof is in burning old round wood. Take a round log that has dried for several years, and it burns just as quickly as split green wood, and doesn't make a good bed of coals like split green wood.

 

[Egon]

Burning of wood

Some information on the burning of wood.

 

[Bigfoot62]

Maybe, just possibly, with split wood there is more surface area exposed to the air that's needed for wood to burn.

He got it right. It's simple physics. More surface area equals faster burn. :thumbsup:

 

[dstig1]

Yep - more surface area is mainly why. Burning only happens where you have the fuel and oxygen present (plus heat). and oxygen is only really present at the surface. More surface means more can burn at any given time.