Fire-by-Friction with Damp Materials

by Dick Baugh

It is a dark and stormy afternoon. The rain is starting to soak through your tattered poncho. The insignificant little streams that you have to cross are now waist high. Yesterday they were little trickles. You finally get to a cave above Wildcat Creek. It is dry inside and even better, there is dry firewood. You reach into your pack for your trusty hand-drill and hearthboard, eagerly anticipating the fire you're going to twirl up. Disaster! They are both damp. What do you do now?

I've been a part of that scenario in the past but didn't have the experience or confidence to propose a solution. I saw three professional outdoor survival instructors fail to ignite a fire-by-friction when forced to use damp materials. I've spent a lot of time thinking about this problem and I think I have a solution.

The First Experiment

I started with a bow drill set with an incense cedar (Calocedrus decurrens) hearthboard and coyote bush (Baccharus pilularis) spindle about 5 inches (12 cm) long by .5 inches (1.2 cm) diameter. This set was quite reliable at creating a glowing ember with moderate effort. I tossed both spindle and hearthboard in a bucket of water for approximately 30 minutes. Next, I removed them from the water, towel dried them and waited another 30 minutes before carving a starting hole and notch in the hearthboard. The wood looked and felt wet. When I applied my usual bow-drill effort it took a little longer than usual before the wood dust started to smoke. I then gave it maximum effort. Plenty of smoke and black char, but no glowing ember. I repeated that sequence (moderate effort from the beginning) several times without any success at creating a glowing ember. What was happening?

The following description is about a bow drill fire, but the principles are the same for all fire-by-friction methods. I hypothesize that after the spindle starts twirling the following sequence of events occurs:

1. Moisture is driven from the wood. Even "dry" wood contains approximately 10 % by weight of water. Very little wood is worn away. Temperature is probably less than 400 degrees Fahrenheit.

2. The wood starts to decompose and char. Smoke starts coming from the wood. The wood is being worn away. The temperature is beginning to rise from 400 to 700 degrees.

3. The temperature of the fine wood particles being abraded off the junction between spindle and hearthboard rises to above 700 degrees. Ignition takes place if the particles are fine enough.

Ignition will not happen until the temperature gets up to a critical level and the critical level depends on the fineness of the wood particles. In "The Miracle of Fire by Friction" (Bulletin of Primitive Technology, No. 5, Spring, 1993), I stated that very fine charred wood particles would start to glow if they were heated up to 700 degrees, whereas coarser particles have to be heated to 800 degrees. You have to get a charcoal briquette's temperature up to about 1100 degrees before it starts to burn.

When full power is applied to a damp spindle and hearthboard then the material is worn away before its temperature is high enough to cause ignition. Evaporation of moisture in the wood is a major source of cooling. In order to get ignition you must get rid of the moisture before trying to create an ember. Fortunately one can heat the wood without wearing it away appreciably by applying a very light effort. This is a universal phenomenon which is critical for success with damp materials. The pressure has to be above a certain threshold before the material is abraded away. Therefore you should be able to drive the moisture away by twirling the spindle gently for a few minutes.

The Second Experiment

Next, I tried to put this theory into practice. I applied very light effort with the bow-drill to the damp spindle and hearthboard until a very tiny wisp of smoke started to appear and then I stopped for a few seconds before resuming the operation. I did this for a couple of minutes: light effort until a little smoke was created, stop a few seconds before continuing with the light effort. After several minutes of very light effort I then applied the moderate effort that I normally use.

Success! The glowing ember told me that I had successfully dried out the wood sufficiently to generate a glowing ember.

Prior to doing this bow-drill experiment I saw a similar thing happen at the 1998 Rabbitstick Rendezvous. One of the young men from Arizona left his sotol hearthboard and seep willow hand drill outside in a rain storm. By applying lots of effort he could get plenty of smoke but no glowing ember. I suggested that he take it easy for a few minutes to dry the materials before working hard. It worked.

Now that you have a glowing ember what do you do with your damp tinder? There is no sun out to dry it. You need some source of heat to dry your tinder. If you are alive you have something at 98.6 degrees. Use it. Wrap your tinder bundle very loosely in a bandanna and put it next to your stomach and then be patient. It may take over three hours to dry. Avoid exerting yourself to the point where you perspire.

The preceding suggestions are neither foolproof or unique. Another method is to construct your spindle and hearthboard from wood taken from the center of a large log.

That is not always possible. I would greatly appreciate hearing from anyone else who has ideas on starting friction fires with damp wood.

This article was first published in The Bulletin of Primitive Technology (Spring 1999, #17)
E-mail your comments to "Richard A. Baugh" at richardbaugh@att.net
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