Building a fire....

Diomedes Industries

Diomedes Industries

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Mar 19, 2007
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I was reading through Cody Lundin's site and came across this:


"Building a fire is a literal statement, and involves two out of the three core concepts of fire making; fuel and oxygen. Put the sticks too close together and you die, (lack of oxygen). Put the sticks too far apart and you die, (lack of the interplay of long wave radiation from one burning stick to the other). Most people fixate on the ignition aspect of fire making. The wise survivor will spend twice as much time learning about the physics of fuel and oxygen placement - building a fire - than on learning ignition. The more skilled one is at "building their fire", the less heat or ignition will be required to light the fire."


I realize that I have spend a LOT of time worrying about the ignition portion of the fire and not spent a lot of time on the physics of building a fire. Are there any books that I can read (or articles, videos, or what have you) that deal more in depth on the topic of fire building?

TF
 
One of the good things about my brief stint in the boy scouts was lots of hands-on time building fires. Since it was probably a good way to keep kids focused and occupied, they let us go for it.

I recall lots of styles and shapes of the structure and categories of sizes of fuel to have on hand.

I'd hope that the modern manuals will still have a bunch of this info in print, but as you already know, there's nothing like firsthand practice.
 
G'day Tal

The following quotes come from a response I made on another forum (october 2007) about starting a fire with wet wood..

"In my experience, the trick to lighting a fire with wet wood is to maximise the heat generated by the fire starter to dry out the wood so it can burn. The attached photo shows the fire lay I use for wet wood.

Step 1, place two larger branches on the ground and parrallel with each other about 10 - 15 cm (4 - 6 inches) apart. This becomes the initial boundary of the fire and won't steal heat from where it is needed like wet rocks will.

Secondly, lay down a parallel single layer of kindling between them, ensuring there are small gaps between each stick to allow air to be sucked in underneath the fire starter. Make sure this initial layer doesn't stack higher than 1/2 way up the inside of the larger branches as you will need a gap for the firestarter between the first and the second layer of kindling (that gets added in step 3). This first layer will not only keep the fire starter off the wet ground, it won't conduct heat away from the fire and into the ground like aluminium foil will. It also provides the added bonus of adding flame to the base of the fire as it dries.

Step 3, Now place a second, much thicker layer of kindling across the larger branches. As the fire starter burns, you want as much of the flame and heat to be making direct contact with this second layer of kindling. If you have large gaps between the kindling you're trying to light, too much of the heat will be wasted by escaping without directly contacting it, reducing the effectiveness of the firestarter.

Progressively add larger pieces (that will dry as the smaller wood underneath burns).

I have been using this method for well over 30 years to light fires and it has always worked, no matter how wet the wood"....



"Before I answer this question, I think it's important to identify the 3 main ways in which heat travels from the source (eg fire) to cooler areas. Once this is factored in, then more of the heat generated by the firestarter can be directed into drying and igniting the kindling (which is the trick to this). These are: Conduction, Convection and Infra red (radiated heat).

Conduction is the most effective form of heat transfer and occurs when heat travels directly between two objects that are in physical contact. An example of this is when you pick up a warm/hot object with your bare hands.

Convection is when the heat leaves the source through a circulating secondary medium like air or water. You can feel this type of heat when you put your hand above the campfire (out of reach of the flames) and can feel the heat in the rising air. BTW, this is why layers are important in cold conditions as they trap layers of air and prevent them from forming convection currents that draw heat away from the body.

Radiated heat is where the heat leaves the source through emittion of Infra Red radiation. This is what you detect when you stand to the side of the fire and can feel the heat radiating from it.

Let's look at these in relation to starting a fire with wet wood.

Firstly conduction. This will occur where the fire is in physical contact with another surface (typically the ground). Free_Trapper has already pointed out why it's a good idea to keep the fire starter off the wet ground. However the material you use to do this will play an important part in reducing the heat conducted away from the fire and directly lead to more heat being available to dry the kindling. Aluminium foil is a very good conductor of heat, that's why I wrap fish in foil before BBQing them (attachment 1). When used as the base of a fire, it will conduct heat from the fire and into the ground. Wood on the other hand is a relatively poor conductor of heat. So if you use a layer of wood as your base / fire pan you will significantly reduce the heat loss to the ground via conduction in the early stages of making your campfire.

Convection. Once the firestarter is lit, then heat will start to rise via the flame and heated air. If you stack a thickish layer of kindling directly above the firestarter, then all this heat must pass around and through the kindling, drying it in the process.

Radiation. The Infra Red is emmitted in all directions from the fire and can be reflected off another surface. However it typically only becomes significant when the fire is already well established and quite hot and as such it and the use of reflectors isn't that important in the early stages of establishing your fires. BTW, in cold conditions the addition of a "reflector" on the other side of the fire will increase the warmth you feel by reflecting this Infra Red back to you.

BTW, IMO when your collecting kindling and larger pieces for the fire, it's worth keeping your eye out for large pieces of bark that can be used to form a roof over your fire to keep the rain off (attachment 2).

Hope this has helped."



This can be seen being put into practice below...

[youtube]gqW0lmj6lzA[/youtube]




Kind regards
Mick
 
I like this one too especially the way they structure the larger logs and recommend that you keep an opening to light your tinder bundle.

It should come in handy because it seems that lots of the firewood bundles available at campsites are huge pieces of wood that won't ignite if you aren't organized about your fire.

http://www.youtube.com/watch?v=nHuu6aInr1w
 
I'm a believer that this is one of those things you have to do (often) to really learn or appreciate. Reading about it won't get you that far. Eventually you'll put together enough during certain circumstances to realize what works and what doesn't.

Not that you have or haven't, I'm just giving generic thoughts.
 
I build a fire the same way, whatever the environment.
Base and brace method. Taught for 40 yrs. in the Air Force SERE program, same way be it arctic, jungle or desert etc.
Platform, big piece of bark or sticks laid side by side. Never do you build a fire directly on the ground. Bigger stick laid sideways on base, pile small twigs against it, side tinder into twigs after you light it. You can lift the brace to regulate air.
Reggie Bennett of Mountain Shepherd has a great youtube video doing this method.
In Scott Gossman's R&R hike in PA we have pics of us building it this way.
Just the way it was taught to me...
 
I am beginning to think I am invisible around here as I have been preaching that in this forum for many years...

I posted about the importance of the fire equation (yet again) earlier today...

http://www.bladeforums.com/forums/showthread.php?t=765095

Regarding Cody's comments, he is specifically referring to too much attention on ignition (heat)... the cool stuff like a ferro rod, making a coal with friction fire, char cloth, etc. And a lack of attention on making a good tinder bundle or pyre, not so much on maintaining a fire as it don't mean squat if you can't get one started.

Sorry for my rant and please check out the other post/videos. Thanks, Chris

Here is the second page of the post with my comments...

http://www.bladeforums.com/forums/showthread.php?t=765095&page=2
 
i just "build a log cabin"

logcabin.gif
 
OKay - I know many ways of BUILDING a fire... I just don't know the physics behind fire - as stated above. Southern Cross talked about how heat is transferred - but I do not understand how or why fire takes place and all the things that would help in the building of a fire.

TF
 
G'day Tal

Since I have already explained the physics behind heat transfer, I guess you now want to know the chemistry behind a fire ?

All right.

Fire is an exothermic oxidation reaction (i.e. it releases energy). This is only possible when the combined bond enthalpy of the products is less than the combined bond enthalpy of the reactants. This difference in energy is released, typically in the form of heat & light.

In the instance of wood fires, the reactants will be the carbon containing compounds within the wood (typically a polymer of glucose called cellulose & ligno-cellulose) and atmospheric oxygen (which acts as the oxidant).

For most wood fires with sufficent oxygen, the majority of the products formed will be carbon dioxide and water. With reduced oxygen, the major products will be carbon monoxide and water. With very little oxygen available, the major products will be carbon and water (have a think about how char cloth is made :D ). The more oxidised the carbon the greater the energy yield (i.e. the hotter the fire) :thumbup:

So there is a need for fuel (wood) and an oxidant (eg oxygen).

However, many exothermic reactions still require an activation energy before the reaction can occur. This is where the ignition source comes in as it will provide the necessary activation energy to kick off the reaction. For those who are into bow drills, then the friction generated by rotating the spindle against the hearth board will provide enough activation energy to start a small reaction (i.e. smouldering wood, aka a coal). The addition of excess oxidant (i.e. blowing on the coal) is generally enough to start a small flame.

Once the reaction is underway (i.e. the wood is burning), then the energy released from the oxidation reaction will generally provide the activation energy needed for the rest of the unreacted reactants (eg the rest of the wood) to start to oxidise and provide a self sustaining reaction (in other words, you have a fire that will burn wood).

So to sum up you will need three things:
(1) A fuel source.
(2) An oxidant (typically atmospheric oxygen).
(3) A source of activation energy (aka ignition source).

Bear in mind wet wood requires additional comment as the water present in the wood will absorb a lot of the initial activation energy required to start the exothermic reaction, as well as limit the access of the oxidant (atmospheric oxygen) to the outer layers of fuel.

BTW, my University major is in Chemistry :D


Kind regards
Mick
 
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i think it has been said before but the best thing you can do is go out and find what works for you.

it will come to you, its instinctive.
 
amazing when you stop and think of it, but primitive man neither knew or cared about 'long wave radiation' when he was building fires.
Still, he seemed to manage...........:D

lots of endeavors are successful due to common sense and practice.
 
Mannlicher said:
amazing when you stop and think of it, but primitive man neither knew or cared about 'long wave radiation' when he was building fires.
Still, he seemed to manage...........:D

lots of endeavors are successful due to common sense and practice.
Click to expand...

say word bro.
 
Base and brace method
Click to expand...

I never knew knew that, I mean, the name, that's how I build a fire, I learned it over years and years of building fires. I learned in the Boy Scouts the rudimentary techniques the box, the Tepee but I eventually found that the base and brace works the best for me.

I usually select the nastiest, gnarliest piece of un-splittable oak as the brace and the flattest piece for the base. I do this because early next morning when I need to start another fire that old nasty piece of oak is still burning and I can easily start up another fire of off it without using my stash of punk and tender. I use this method in my wood stoves too.

Starting a fire is one of my earliest skills, I gather material sometime days in advance, I cover my foraged wood and the wettest of it I line the fire with. I was about 12 years old when I learned about flint and steel. I have never failed to start a fire but I've never been in a wilderness survival situation and we all know that's when Murphy really bites our butts.

I don't know all about the science of it but I'm going to go back and read that stuff until I do, thank for that SouthernCross.

You may not need to know the physics of it to start a fire but in the case of desperation and failure something in the science of it my spark another idea which could save the day.
 
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