Dumb question about firemaking...

gazz98

gazz98

Joined
Sep 3, 2008
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Everytime I see folks making fire on tv (Dual survivor, Bear, etc) or on utube, I see folks blowing on a fire to get it started. My grandpa taught me to gently fan oxygen into a fire since blowing on a fire incorporates more carbon dioxide into it. Obviously, if both hands aren't free, blowing on it makes sense since we don't convert all of our oxygen intake into CO2 and it is better then nothing. Or is the difference in the percentage of oxygen in either method negligible?

ps I tried searching and didn't find a similar topic, sorry for the dumb question.
 
It works very well, as it adds a longer burst of air to the fire. you concentrate your breath, with a big breath blow slowly so it gets a longer burst of air and it works very well.
 
The oxygen extraction efficiency of the human lung is about 25%. This of course changes in relationship to breathing rate, extraction efficiency drops with heavier breeding slightly. Given that air consists of a little more than 20% oxygen, we really do not change the oxygen content that much. Exhaled air contains about 15% oxygen. The main difference is the velocity that can be attained by fanning versus blowing. Since, within a confined space, you can often blow more air (or concentrate it) than you could lets say fan it (assuming we are talking your hand and not a big piece of fanning material), then the rate of delivery of O2 by mass/time is higher by blowing even if the O2 concentration is less.

Alternatively, I've been told that fanning an ember is more productive than blowing because the moisture on your breath weakens the flame. Here this argument would it seems holds water (HA HA HA HA....ROFL...LOL...HE HE HE HE, I'm killing myself here). The relative humidity of human breath approaches 100%. So in the tropics, breathing may make no difference at all since humidity is around 100% anyway, but in the desert - perhaps blowing could be less efficient.

I have no scientific data to back it up, but intuitively it would seem like moisture would more likely impact an ember because of the inherent weakness of the combustion reaction at that stage and might have less effect on an actual flame. Maybe a chemist or physicist can correct me on this one.
 
Your breath also has a venturi effect, dragging surrounding air along with it into your fire bundle. I can no longer blow, so I do fan. Either works. If you watch the old Charlton Heston/Brian Kieth movie "Mountain Men", you will see Heston blowing and then waving the tender bundle in a circular motion. I've used a section of river cane to blow on a bundle and that works well too. One negative of blowing is the moisture in your breath. Sometimes it matters, sometimes not.
 
What Codger said.

Blowing is good for a small spark, because you can aim a stream of air better. But fanning, I find, is better for a larger patch of tinder that may have two or more hot spots. Gentle but firm fanning can get all of them to ignite at once.

I've had the best success blowing when working with a lump of coal that's still warm from an old fire the day before. Pile the tinder on the hot spot and blow over the top of it. Fanning, ironically, would just blow the tinder off the hot spot.

So I guess to follow up on Codger's last sentence, experiment with both. Both work under different conditions.
 
I used to carry a thin Frisbee made with a nylon fabric stretched over round wire. It was very thin and lightweight, but a little fragile. I would use it to fan the flames once the tinder had already ignited some of the tinder. It worked. A laminated piece of paper or if I have it, a small and thin cutting board is what I use.
 
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