Tuesday, November 10, 2009

Making Fire

Frankly it has been a while since the last time I've made fire but it is something I just want to review and get down somewhere.

There are three things you need to create fire: Oxygen, fuel and heat. If you can breathe you have plenty of oxygen for the fire. Burning is defined as combining with oxygen so it is a very important part of the mix. Technically rusting is burning, but it is not happening at the fast enough rate to give us a useful amount of heat. For fuel, wood is great and so is charcoal, coal, oil and other hydrocarbons; just about anything that is dry and has lots of carbon in it. Heat is important in that what you are trying to do is get the volatile compounds to boil off and begin combining with oxygen.

Starting up some charcoal for the grill can be a real pain. You crumple up a page of newspaper and light it and when you come back the paper is all burned up but the charcoal is still cold. Then you might wad up half the paper and this time not even the paper is burned. There has to be a better way! All you really need is a one sheet but drizzle about a teaspoon of cooking oil on it before crumpling it up. The oil burns but at a lot slower rate then the paper, this allows the  charcoal or even wood to catch fire and in about 15 minutes you'll have a ready to cook fire.

This works even better with a chimney starter. The ones from the store are nice and big but you can make one from a metal #10 can. This is an old trick as well. I first learned it as a Boy Scout, cut the top and bottom lids off and around the bottom punch holes using a church-key can opener, this lets air in to help the charcoal to burn. You'll need some pliers to remove the chimney once the fire is going.

A wood fire is not much harder then a charcoal fire but there are some prerequisites. The wood needs to be seasoned and I am not talking about salting the wood.  Seasoned means the tree was downed some time ago and the wood allowed to dry out a bit. If you are out in the woods and trying to find dry wood you need to look for downed limbs and the like, trees that have fallen down at often rotted on the bottom but usually the limbs sticking up are fine and dry. If it has been raining you need to look for protected places under partially fallen trees, rock outcroppings and the like. Once when we went to summer camp it rained for an entire week before we got there and for days after. There was no dry wood to be found, we even split wood to try and get something sort of dry but it was just raining too much. Finally, on the third day one of the leaders went back to his car and siphoned out some gas, we built a big double-ringed stone firepit, piled in the wood we had collected and after shooing everyone back about 100 feet he poured on the gas, tossed a lit match in and dived for cover. That finally got the fire going and it took a lot of work to keep it going. Wet wood will burn but it needs to sit by the fire for a while to dry out enough for it to catch.

Mastering fire is a great basic skill. A big bonfire is easy, a good cooking fire quickly is different and a long lasting fire is different again. Wood is a different material from charcoal and coal and peat. A bonfire can be as easy a some kindling and small wood surrounded by a teepee of bigger wood. A good cooking fire is best made with hardwoods since they create coals that are easy to cook on and they should be stacked in a log cabin arraignment with the big wood at the top. A long lasting fire that needs to last the night is a lot like the log cabin for the cooking fire but put the small stuff at the top in a lattice arraignment and start the fire at the top and it will burn down to the heavier wood.

One of the fun tricks we did as scouts was to do trick lights, Using some trick or another to start a fire to impress the Tenderfeet on their first campout. These would be things like using a 9V battery to ignite a steelwool pad, after a suitable incantation. My favorite was the 'comet' run a length of magnet wire from the center of the firepit up into a nearby tree. hang a lighter fluid soaked roll of toilet paper and have someone in the tree to light it and it will come roaring in for a spectacular effect. Okay, that one should not be used expect maybe during a drenching rain storm.

Like any fire based application keep a fire extinguisher around.

As important as it is to know how to create fire it is also important to know how to turn a fire off. In this case instead of trying to bring the three requirements of fire together you are trying to separate them. Once on a campout we went on a big hike and some of the other scouts weren't really prepared for that and wanted to make a fire to cook their lunch, they lit up a paper bag to get it started but the wind picked it up and dropped it in a field full of dry grass. We all rushed over and stomped on it and dumped our canteens on it and we got it out in just a few seconds but it is amazing how fast a fire can spread in dry grass.

Throwing water on a fire works because it limits the fuels exposure to oxygen, getting fuel wet tends to make it useless and because water has such a high specific heat it can absorb a huge amount of heat thus keeping things cool. I guess you could also make a good water thrower using soda water and Mentos. Though an Indian pump is what we kept handy.

One of the first fire extinguishers were the ones that produced CO2 to starve the fire of oxygen, and that was easily made with baking soda and vinegar. In the Lord of the Rings documentaries it was fun to see them figure out that to extinguish the torches they used buckets of dry ice. Dry ice is solid CO2 as it sublimates it filled the bucket with CO2 gas and so they could pop the torches in there and they would go out, but they could relight them right away for the next scene without a problem. Water would have worked but it would have taken days to dry and be ready to go again.