# Burning Saw Dust in a Wood Stove



## woodshavings (25 Jan 2008)

I have just installed a Relax R2 wood stove in the workshop. No problem burning offcuts and shavings but I am wondering about fine wood dust.
I know fine dust can flare back or even explode if tipped onto a burning fire. 

Any advice on how to safely burn this type of dust gratefully received!

Thanks, John


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## mr (25 Jan 2008)

In paper bags? 

Cheers Mike


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## Anonymous (25 Jan 2008)

As far as I am aware, only very fine dust (such as flour) in the atmosphere will explode - can't see swdust doing that .

Bags that are tightly packed should be good as they would form a sort of fuel pellet which will burn more slowly


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## staffie (25 Jan 2008)

There have been a few threads on this topic in the past, here is a link you may find usefull.

http://www.echotech.org/technical/techn ... iquete.pdf 
(This was taken from a previous thread.)

I make my sawdust in bricks and burn them that way. 

Jock


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## tim (25 Jan 2008)

I don't add sawdust to mine when its going, just to start it. If you fill it and keep both vents open until the gases have ignited a burner full of sawdust can keep going all day without need of a refill.

Cheers

Tim


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## Wanlock Dod (25 Jan 2008)

Tony,

When I was at school we were shown a custard powder experiment. Briefly, a catering tin (with lid) containing a pipe (as in smoking pipe, with the mouthpiece outside and bowl inside) and a candle. Fill the pipe bowl with custard powder, light the candle, put the lid on and blow into the pipe mouthpiece. The powder is dispersed and mixed with the air, the mixture is ignited and the lid hits the ceiling as a result of the explosion. Pretty cool, although I doubt it's still performed in schools.  

I've no doubt that wood dust, being a finely divided organic material, would do much the same. That said, I still smoke in my workshop (but then I doubt I would ever get enough sawdust in the air to create a potentially explosive mixture).

If I wanted to burn sawdust I'd do as Mike suggests and put it in paper bags. As it is I compost mine.

Cheers,

Dod


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## Racers (25 Jan 2008)

Hi, Tony
There had been a discuion on the Old Tools about this check out 
http://people.iarc.uaf.edu/~cswingle/ar ... 81#message
Seems like care is needed.


Pete


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## Paul.J (25 Jan 2008)

I once tried mixing torn up newspapers and wood shavings for my brother in law once,as he has an open fire.
Mixed it up in a bucket,fairly dry but just enough for it to bond and put the mix into old ice cream tubs to dry out.
He said it worked fine but took so long to dry out.
Job for the summer months :wink:


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## Shadowfax (25 Jan 2008)

Tony is spot on. The dust must be entrained in the atmoshpere for explosive conditions to be right. 
The custard powder experiment proves the point. 
I would use the sawdust to start the fire, like Tim says, and you will be fine.

Cheers.

SF


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## woodshavings (25 Jan 2008)

Thanks for all the info...that link from Pete makes scary reading.

I do compost most of my sawdust (mix it with grass cuttings) but not those that contain any mdf or chipboard dust.

(I know, I shouldn't use mdf or chipboard  !)

The suggestions of only using it initially or added in paper bags seem on the mark!!

Thanks again, John


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## toolsntat (25 Jan 2008)

We used to have one of those Tangyes cast iron burners in the workshop where I cut me teeth...
It was a cold place in the winter and we used to get it drawing that well ( mmm memories of those perfect toasted marmalade sarnies I used to have :wink: ) that the sides would glow :roll: 
One day I emptied the belt sander bag onto the fire shovel (same as the railways used), flipped the front down and as I had done on previous occasions shovelled it in...
Normally this wasn`t a problem but this time I gave it that sort of a stoking the boiler action and youv`e guessed it, it went up like a goodun :shock: :shock: :shock: 
The stove separated at all the joints dislodging the chimney flue , the flashback singed any stray hairs I was unfortunate to have facing it and the front of my chunky knit sweater was turned into something resembling a string vest   
Nough said it was a lesson well(??) learned... 
We never did that bit about fine paticle explosions at school :evil:


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## Bean (25 Jan 2008)

If you roll newspaper and fill the roll with sawdust it will burn nicely on an open fire, some of mine go that way. I also light fires with them. Some of the eco shops sell a wooden dowel to form the newspaper around and a cup to form the ends. i just twist them.

Saw dust is considered an explosive medium, but only when it is mixed freely with air, contained it will burn slowly.


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## TNWoodwright (26 Jan 2008)

Hi
Being "murican I mostly lurk. That being said you can burn sawdust safely, maybe 

What I do is put a 3in tube vertically in the center of the stove. Pack sawdust around it as tight as you can. Pull the tube out and light the hole. as low as you can. I generally just throw a match in. the sawdust will burn in a circle outwardly. Mine is about 24 in round and 18in high and last about 3 hours.

I'm on the road now but if your interested I will post some pics in a week or so.

If you just want to try it out. Take a gallon can. put a tube in it and pack sawdust around it. pull the tube and light. You'll see what I mean Nice little on the job heater 

Dave


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## woodshavings (26 Jan 2008)

Hi Dave,
welcome to the forum - 'muricans are most welcome - you're no longer a lurker !!
Thanks for your suggestion (and all the others), I think I've got it sorted now. 
John


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## DaveL (26 Jan 2008)

I have a wood burner in the shop and all of my shavings and saw dust go into it. As shown by the exploding stove story above if you flick the fine dust in the results can be exciting. :shock: 
I have fitted a long handle to my shove shovel so I can put the dust down on the fire, instead on tossing it in though the door. This works a treat.

I have been known to stack bags of shavings in the garage during the summer as fuel for the workshop in winter. :roll:


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## Anonymous (26 Jan 2008)

Wanlock Dod":1aojj6bu said:


> Tony,
> 
> When I was at school we were shown a custard powder experiment.
> Dod



Yep, that's what I said, only very fine powders will explode as far as I know and wood dust is too course (I think :wink: )

I feel some experimentation coming on..........


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## Anonymous (26 Jan 2008)

Well, me and the girls have been outside burning wood, sawdust and wood shavings for the past 90 minutes and I can report the following:

a) I stink of smoke! :lol: 
b) the girls stink of smoke!
c) wood offcuts burn much better and hotter than wood shavings and/or sawdust (not tried it highly compressed)
d) no matter how I threw the sawdust into the wood burner, it did not even flare up, never mind explode (pretty disappointing as the girls were excited about the possibility :lol: )


Basically, the sawdust and wood shavings from the P/T more or less smothered the raging fire and it died down quite a lot. rather than the shavings flaring up as I would expect, they sort of smoldered and burnt much more gently than the wood offcuts.

Ohh, the toasted marshmallows are very nice indeed  :wink:


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## tim (26 Jan 2008)

I have found that it very much depends on what wood is used. Walnut and oak shavings don't flare up much at all but soft wood does. Maybe not very pc but MDF seems to burn the hottest.

You can certainly get a very impressive flare up if pouring on MDF dust or anything from a sander. DAMHIKT :twisted: :lol: 

Cheers

Tim


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## TNWoodwright (27 Jan 2008)

TNWoodwright":2qngq9v3 said:


> Hi
> Being "murican I mostly lurk. That being said you can burn sawdust safely, maybe
> 
> What I do is put a 3in tube vertically in the center of the stove. Pack sawdust around it as tight as you can. Pull the tube out and light the hole. as low as you can. I generally just throw a match in. the sawdust will burn in a circle outwardly. Mine is about 24 in round and 18in high and last about 3 hours.
> ...




Well rubbish, My apologies!! Woke up here in the middle of the night. I forgot to add that this works by drawing air up through the "tube" So if you try the bucket it has to be on some bricks with a hole in the bottom, or use this in a stove it has to draw air up through the hole you made. So there has to be a grate in the stove. My stove draws air below the fire box. Some things you don't think about when you do it every day.

Here is a link.

http://www.motherearthnews.com/Green-Ho ... Stove.aspx

Check out the images.

DOn't know why it comes up with the "report to moderator" But you can find it by googling sawdust stove and look for the mother earth news link.


And thanks for the hello!


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## DaveL (27 Jan 2008)

Hi Dave,

Welcome to the forum.

Your link has been caught by our spam trap, that will stop once you have a few more posts to your name, here it is:

http://www.motherearthnews.com/Green-Ho ... Stove.aspx


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## Losos (27 Jan 2008)

TNWoodwright":2khgbv69 said:


> Hi
> Being "murican I mostly lurk. That being said you can burn sawdust safely, maybe
> 
> What I do is put a 3in tube vertically in the center of the stove. Pack sawdust around it as tight as you can. Pull the tube out and light the hole. as low as you can. I generally just throw a match in. the sawdust will burn in a circle outwardly. Mine is about 24 in round and 18in high and last about 3 hours.
> ...



Welcome to the forum Dave,
That's an interesting idea, my wood burner is unique in that it has a door on the side, it's a very crude design (Most things in this part of Europe are) but it does give out a lot of heat once it gets going. I don't need to use sawdust having plenty of rubbish timber to burn at the moment so I put it on the compost, but the time may come when I want to burn it .


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## les chicken (31 Jan 2008)

I have had the R2 for a couple of years in my workshop, now on its second flue. Burning sawdust is no problem as long as you use it to start the fire and not top it up.
When the R2 is cold I fill it up to the flue and push my fist into the centre to make a hollow. Some paper or a firelighter in the hollow and close both vents halfway. This will burn for about an hour or so and then top up with logs or off cuts NOT sawdust or shavings.
If you put sawdust or shavings on a hot fire they will smother it but burn from the bottom. The trouble starts when the gasses ignite above the sawdust, usually results in the top being blown off or flames through the control vents.
So as long as you use sawdust or shavings when the fire is cold and light from the top there is no problems.

Les

PS speaking from experience.


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## woodshavings (31 Jan 2008)

Thanks Les,

I have now been using it and also found the top was lifted off a couple of times after topping it up with sawdust (in paper bags) on a hot fire bed- I wondered what caused it.

I have the vitreous flue - I hope it lasts more than a year!

Cheers, John


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