# What causes some wood to leave more ash than others?



## StihltheOne (Oct 14, 2008)

Why is it that some wood leaves a ton of ash, and others hardly any? I guess that I have never gave it much thought as to why, I just accepted the fact that some does and some doesn't.


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## KsWoodsMan (Oct 14, 2008)

I always figured the heavier wood left more ashes since they gave off more BTUs.

This article kinda summed it up for me. http://www.fao.org/docrep/t0512e/T0512e0o.htm#4.1.2 the wood gasifier goto the last paragraph where it starts with Ash content. Some biomass is higher , in the 0.9% - 0.14% by weight. few are lower. 


HTH


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## chainsawaddict (Oct 14, 2008)

KsWoodsMan said:


> I always figured the heavier wood left more ashes since they gave off more BTUs.
> 
> This article kinda summed it up for me. http://www.fao.org/docrep/t0512e/T0512e0o.htm#4.1.2 the wood gasifier goto the last paragraph where it starts with Ash content. Some biomass is higher , in the 0.9% - 0.14% by weight. few are lower.
> 
> ...



I think it has to do with how the wood stores cellulose. I just took a botany class last semester! I should remember this stuff, its stuff ill actually use!


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## abohac (Oct 15, 2008)

StihltheOne said:


> Why is it that some wood leaves a ton of ash, and others hardly any? I guess that I have never gave it much thought as to why, I just accepted the fact that some does and some doesn't.



I always thought it had something to do with the bark. I know it I throw cottonwood in with bark it leaves alot more ash than cottonwood without (same with dead elm).


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## Mike Van (Oct 15, 2008)

I've found Ash to leave the most - Wonder if thats why they named it "Ash"?


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## Wood Doctor (Oct 15, 2008)

Mike Van said:


> I've found Ash to leave the most - Wonder if thats why they named it "Ash"?


I think ash wood might do that because lots of people think it is dry and ready to burn when it's not quite ready yet. Hard wood that is still a little green leaves behind the most chunks that look like small cinders. Cold fires that are starved for air generate more of them. These chunks can be tossed right back into the next fire and they will ignite and burn to a powder.


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## savageactor7 (Oct 16, 2008)

We mostly always burn wood that's been seasoned for a couple summers and notice very little difference in ashes. Ash, elm, Maple, Black Cherry, Poplar, Apple, Willow.

Also burn dry punky wood in shoulder season....very little ash with that cause it lost over half its original weight. All pretty much the same ash wise...they do coal up a little differently though, esp Locust.


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## woodguy105 (Oct 16, 2008)

Wood Doctor said:


> I think ash wood might do that because lots of people think it is dry and ready to burn when it's not quite ready yet. Hard wood that is still a little green leaves behind the most chunks that look like small cinders. Cold fires that are starved for air generate more of them. These chunks can be tossed right back into the next fire and they will ignite and burn to a powder.



:agree2: 

My experience has been the hotter and longer the burn, the whiter and finer the ashes and the glass is clean in the morning!

Moist wood burned will end up forming kind of a chunky mat of coarse ash on the bottom of the stove.


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## timberwolf (Oct 16, 2008)

http://www.fpl.fs.fed.us/documnts/pdf1993/misra93a.pdf

Very technical read about ash.

Hotter and longer burns will burn off more volitiles, but looks like a big factor in ash is mineral content of different spiecies.


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## habanero (Oct 16, 2008)

timberwolf said:


> ...but looks like a big factor in ash is mineral content of different spiecies.



I didn't read the document you linked to, but you're exactly right. True "ash" (as opposed to unburnt carbon-based material) only comes from things that won't combust or aren't volatile. Rougher-barked woods, with the bark left on, do tend to leave more ash, but that's mostly because of small amounts of dirt trapped in the bark (both externally and in the bark itself from wind deposition). I don't know, but trees may store minerals in the bark or the layer just below the bark as well-that would lead to more ash from those pieces too.


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## Crofter (Oct 16, 2008)

Cant find the link to it right now but have read articles on using different biomass for pelletising and since the amount of ash formed in the cup sized burners of pellet stoves is a concern it was compared quite extensivley. Any of you that farm have burned binder twine that I think is made of sissal fibre will know what a huge mass of ash it leaves behind. I know when I burn poplar i have to empty the ash a lot more often than when burning oak. Not sure about the weight difference but sure a lot more volume.


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