Birch bark, undressing mother nature.

The inner layer (bast or phloem) which in Scandinavia is referred to as the actual bark, have also had its uses, specifically for tanning which is the process of treating animal hides and turning them into leather.

A Key Resource

Birch bark has in fact played a major role in the everyday life of the Eurasian and North American peoples for over 5000 years, for a wide variety of useful and necessary items. Baskets, boxes, cooking vessels, canoes, rucksacks, musical instruments, writing material, shoes and shelters – are just some of the many things that were made from this extraordinary material.

It has also been used for making birch tar or birch pitch (see picture right), a substance high in various phenols that is derived from the dry distillation of the bark that were used for many different purposes such as an adhesive, disinfectant and as the final water proofing of high quality leather (Russia leather). In the video right bushcraft expert Dave Canterbury shows how to make birch oil, a finer quality version of birch tar.

The oil is an antiseptic and can be used on your skin as an insect repellent, on wounds to prevent infections and to treat rashes or eczema. Birch bark was in fact one of the largest Scandinavian exports along with pine tar, the lifeblood of the north, until the 17th century; you could even pay your taxes with it.

A Natural Fungicide

The fact that birch bark is 100% water proof has surely played a major role in its usefulness, and so has its flexibility – but the high content of betulin (a substance with fungicidal properties) also makes birch bark perfect for constructing various containers for food preservation, or for simply holding and keeping water fresh. Thanks to the betulin the bark will not only perform all these very important tasks but also last for a very long time, making it the perfect choice for moisture barriers for a wide range of applications, e.g. in basically any type of natural shelter construction.

It is advisable to harvest birch bark from spring up until the middle of July. During this period the birch is sapping which makes harvesting a lot easier. The birch bark comes off the trunk with ease but it has a natural tendency to curl up and when dry it can be impossible to uncurl again, so for this reason the sheets needs to dry under compression, which forces the sheets to stay flat.

The birch grows its bark differently from most other species of trees. Instead of having its fibres run vertically (in the same direction as the trunk) it grows horizontally (around the trunk). It is a very tough material, like a mix between leather and cardboard, of which you can remove very large sheets that later can be cut into the right size and shape for the intended purpose.

Canoes made from birch bark ...

Old birch logs have been found in bogs, under water, and when lifted up the bark have still been white and fresh as the day it went in, while the wood is completely rotten and has basically turned into a black soup that can be poured out, essentially leaving an intact birch bark tube.

It has such resistance to water that some native American tribes even made their canoes for centuries using birch bark, resulting in a watertight and very light canoe that could easily be lifted and carried, yet still be very durable if maintained correctly. These vessels are truly magnificent works of art which intuitively feels brittle and not very long-lasting, but the fact is that some of these canoes were in active use for over 100 years. They were highly treasured items that were treated with great care and respect, being passed on from one generation to the next, as were the construction techniques.

Bushcraft expert Ray Mears is shown the traditional techniques of building birch bark canoes by Pinock Smith, a canoe builder from the Algonquin tribe.

A Unique Building Material

Being 100% waterproof and having a natural resistance to fungus and rot means that birch bark is a perfect moisture barrier for natural building. The traditional Scandinavian sod roof (a Scandinavian vernacular) can definitely attest to this fact. A similar application is to use a few layers of birch bark between sill beams and foundation to protect the timber from any possible condensation that might form on cold, hard surfaces such as stone.

For any natural builder looking to use natural or non-industrial materials it is hard if not impossible to find a local, organic material which can withstand moisture for such a long time as birch bark. Most people living in birch-rich locations have historically used birch bark as moisture protection for a variety of different applications when constructing shelters. The indigenous people of Scandinavia (Sami) certainly knew how to make the most of this resilient building material. Some versions of their tipi-like dwellings, called goahti, were completely covered with birch bark. The peat or sod goahti (see right) is a variety covered with sod to keep the birch bark in place and also work as an insulating wrap, just like a Sod Roof. Some native American tribes used birch bark when constructing their traditional wigwams, much in the same way as the Sami.