The bark of the paper birch (Betula papyrifera) is preferred for canoe building because it could be obtained in quite large sheets clear of serious blemishes; because its grain ran around the tree rather than along the line of vertical tree growth, so that sheets could be “sewn” together to obtain length in a canoe; and because the bark was resinous and not only did not stretch and shrink as did other barks, but also had some elasticity when green, or when kept damp. This elasticity, of course, was lost once the bark was allowed to become dry through exposure to air and sunshine, a factor which controlled to some extent the technique of its employment.
When one finally has found a tree that one thought might be appropriate – one that not only grew tall but had long ago shed any small branches from its lower trunk – one has to test the bark itself. Not all trees provide good canoe bark. Sometimes it wasn’t thick enough. The test was to cut a piece off and twist and turn it this way and that. If it didn’t crack it was good enough to make a birch bark canoe. When the bark passed the twisting and turning test then one talks to the tree and thank it for providing one with a canoe.
The bark of the birch tree has an aromatic odor when freshly peeled, and is chalky white marked with black splotches on either side of limbs or where branches have grown at one time. Elsewhere on the bark, dark, or black, horizontal lines of varying lengths also appear. The lower part of the tree, to about the height of winter snows, has bark that is usually rough, blemished and thin; above this level, to the height of the lowest large limbs, the bark is often only slightly blemished and is thick and well formed. The bark is made up of paper-like layers, their color deepens with each layer from the chalky white of the exterior through creamy buff to a light tan on the inner layer. A gelatinous greenish to yellow rind, or cambium layer, lies between the bark and the wood of the trunk; its characteristics are different from those of the rest of the bark. The horizontal lines that appear on each successive paper-like layer do not appear on the rind.
The thickness of the bark cannot be judged from the size of a tree and may vary markedly among trees of the same approximate size in a single grove. The thickness varies from a little less than one-eighth to over three-sixteenths inch; bark with a thickness of one-quarter inch or more is rarely found. For canoe construction, bark must be over one-eighth inch thick, tough, and from a naturally straight trunk of sufficient diameter and length to give reasonably large pieces. The “eyes” must be small and not so closely spaced as to allow the bark to split easily in their vicinity.
The bark can be peeled readily when the sap is flowing. In winter, when the exterior of the tree is frozen, the bark can be removed only when heat is applied. During a prolonged thaw, however, this may be accomplished without the application of heat. Bark peeled from the tree during a winter thaw, and early in the spring or late in the fall, usually adheres strongly to the inner rind, which comes away from the tree with the bark. The act of peeling, however, puts a strain on the bark, so that only tough, well-made bark can be removed under these conditions. This particular characteristic caused Natives in the east to call bark with the rind adhering “winter bark,” even though it might have been peeled from a tree during the warm weather of early summer. Since in large trees the flow of sap usually starts later than in small ones, the period in which good bark is obtainable may extend into late June in some localities. Upon exposure to air and moisture, the inner rind first turns orange-red and gradually darkens with age until in a few years it becomes dark brown, or sepia. If it is first moistened, the rind can be scraped off, and this allowed it to be employed in decoration, enough being left to form designs. Hence winter bark was prized.
When one decides to make a birch bark canoe one should put emphasis on the importance of starting with a good piece of bark. The bark should be about one quarter inch thick and not crack when it was bent or twisted. It can take a long time to select just the right tree.
The birch tree that is to supply the bark is usually selected far in advance of the time of construction. By exploring the birch groves, the builder locates a number of trees from which a suitable quantity of bark of the desired quality could be obtained. Samples of the bark of each tree were stripped from the trunk and carefully inspected and tested. If they separated into layers when bent back and forth, the bark was poor. If the “eyes” inside the bark were lumpy, the bark in their vicinity would split too easily; this was also true if they were too close together, but if the eyes on the inside of the bark appeared hollow there was no objection. Bark that was dead white, or the outer surface of which was marked by small strips partly peeled away from the layer below, would be rejected as poor in quality.
Peeling bark off the tree requires great care. Only a knife and hands are used as not to mark the bark. A cut is made around the diameter at the base and the top of the tree. Another long cut is made down the length of the tree between the two slices. The bark is then gently peeled away from the tree; sometimes warm water is used to make the peeling easier and keep the bark moist. Peeling the bark from the tree, does not kill it if the cambium layer (or inner bark) remains after the bark is peeled. The tree can heal and generate a new outer layer of bark. Usually more than one tree is needed to be peeled for each canoe.
With a knife, the bark is cut with the blade held at an angle to make a slashing cut; holding a sharp knife upright, so as to cut square to the surface of the bark, makes the tool stick and jump, and a ragged cut results. An axe blade can also be used in cutting bark; with such tools, it is customary to tap the head with a maul to make the cut. It is usually necessary to make only the longitudinal cut on the trunk of the birch tree, as the bark would split around the tree with the grain at the ends of this cut.
Once the vertical cut is made to the desired length, one edge of the bark is carefully pried away from the wood with the blade of a knife. Then the removal of the bark can proceed more rapidly. Instead of starting the bark with a knife blade, some use a small stick, one end of which was slightly bent and made into a chisel shape about three-quarters of an inch wide. This is used to pry the bark away, not only along the edge of the vertical cut, but throughout the operation of peeling. Another tool, useful in obtaining “winter” bark, which is difficult to strip from the tree, is a piece of dry, thick birch bark, about a foot square, with one edge cut in a slight round and beveled to a sharp edge. The beveled side is inserted beneath the bark and rocked on its curved cutting edge, thus separating the bark from the wood with less danger of splitting the bark.
After the bark has been removed from the tree, it is handled with great care to avoid splitting it along the grain. Even in quite warm weather, the bark is usually heated slightly with hot water that is applied unless the inner rind is to be used for decoration. Then the sheets are rolled up tightly in the direction of growth of the tree. This makes a roll convenient for transporting and also helps to prevent the bark from curling. If the bark is not to be used immediately, it is carefully submerged in water so that it will not dry out before it was fitted to the canoe.
It is believed that before steel tools were available birch-bark canoes were commonly built of a number of sheets of bark rather than, as quite often occurred in later times, of only one or two sheets. The greater number of sheets in the early canoes resulted from the difficulty in obtaining large sheets from a standing tree. Comparison of surviving birch-bark canoes suggests that those built of a number of sheets would have contained the better bark, as large sheets often included bark taken from low on the trunk, and this is usually of poorer quality than that higher on the trunk.
The wooden part of a birch bark canoe are almost all made of cedar. In the east, this is Eastern White Cedar, Thuja occidentalis. Cedar grows in swampy areas and on shallow dry soil and averages about 45 ft in height and 1 ft in diameter. Large trees may grow to 3 feet in diameter. It often grows in dense clumps. The wood is good for canoe building because it is light in weight, easy to split and bend and resistant to decay.
Cedar trees are common in Ontario but finding good cedar for a canoe is not easy. It must be straight and knot free and big enough around to make useful pieces. To see if the grain is straight, peel off a strip of bark vertically, and see if it goes up straight or curves around the tree. If the bark curves, then the wood inside will too. Knots are to be avoided because they weaken the wood.
Cedar is used for the gunwales, ribs and sheathing in the canoe. The longest pieces are the gunwales so a tree that is sufficiently long and straight must be found for them. For the ribs and sheathing, pieces that are about 5 feet long are long enough.
A cedar log is split rather than sawn into pieces. This makes the wood much stronger since you are following the grain. Also, it requires few tools. A cedar log is split green. It is first split across the growth rings: lengthwise down the middle into two halves, then again into quarters and depending on how big the log is, again into eighths.
Then the split pieces are split along the growth rings to make flatter pieces. The ribs are split roughly to shape, then finished with an axe, knife or other tools. The sheathing is split very finely until it is barely the thickness of a piece of thin cardboard. Splitting cedar is a wonderful process. It smells nice and sounds neat.
The initial splitting is done with splitting wedges, then a froe and a mallet can be used to start the split and the rest done by pulling the pieces apart with your hands. For the fine splitting, a knife is used to start the split. Getting cedar to split evenly must be practised a bit but is not hard if the wood is straight. If the split starts to go off centre, pull a bit more on the thicker side. After starting a split, holding the wood between one’s legs can help control the split.
The wood of the eastern white cedar (Thuja occidenfalis) is supple, light in weight and decay resistant. it is therefore ideal for the construction of birch bark canoes, and is used for a large number of parts: ribs, sheathing, gunwale members, stempieces, and headboards. Some builders use young spruce for the gunwales, but it is harder to bend.
Green cedar wood is preferred, although a dry fallen tree is sometimes used. A frame saw and an axe are used to cut down the tree; then the trunk is cut into various lengths. The rest of the work is done by hammering a wedge into the trunk with the axe, splitting it from end to end and then quartering it. This rough preparation makes it easier to transport the cedar back to camp, where an axe blade or a strong knife is used to split one end of each piece. The builder then pulls the two strips apart with his hands. The cedar is always cut with the grain, following the growth rings. Later the pieces will be fashioned into ribs, sheathing strips, and so on, with the help of the crooked knife. But until the building is actually begun, the cedar is placed in water to keep it from losing its flexibility.
No nails or screws are used to hold a birch bark canoe together. Instead, the pieces are lashed together with peeled and split tree roots, usually from spruce trees, although jack pine roots can be used too. The material used for “sewing” together pieces of birch bark is most commonly the root of the black spruce (Picea mariana), which grows in much of the area where the paper birch exists. The root of this particular spruce is long but of small diameter; it is tough, durable, and flexible enough for the purpose. The tree usually grows in soft, moist ground, so that the long roots are commonly very close to the surface, where they can easily be dug up with a sharp stick or with the hands. In some areas of favorable growing conditions, the roots of the black spruce can be obtained in lengths up to 20 feet, yet with a maximum diameter no larger than that of a lead pencil.
A pick axe can be used at first to pull up a root. Then the root is gradually pulled out of the ground, following it as it goes under and over other roots.
The best place to get spruce roots is in sandy soil where the trees are not too close together. If you collect roots where the trees are quite close together, the roots are intertwined, making digging them up harder. In sandy soil, the roots can be straighter.
Once you have a bunch of roots, take them and peel the bark off them right away. It’s much easier to peel them fresh than to peel them once they have dried. Some people split them and then peel them and others peel and then split.
To peel the bark off roots you can use your fingernails or a piece of wood with a notch cut in it, or two pieces of wood held together. The idea is to scrape the bark off but not damage the inner root. Once the roots are peeled and split, roll them up to store them.
When you are ready to use them, soak them in a bit of warm water for a few minutes until them are flexible.
Thus, roots for “sewing” are gathered, split, and rolled up, then placed in water so they will remain flexible. Sometimes they are boiled as well, just before being used.
To make a bark cover watertight, it is necessary to coat all seams and to cover all “sewing” with a waterproof material, of which the most favored is “spruce gum,” the resin obtained from black or white spruce. The soft resin was scraped from a fallen tree or from one damaged in summer. Spruce gum could be accumulated by stripping a narrow length of bark from trees early in the spring and then, during warm weather, gathering the resin that appeared at the bottoms of the scars thus made. It was melted or heated in various ways to make it workable and certain materials were usually added to make it durable in use.
The spruce gum is gathered and tempered. Before metal kettles and frying pans became available to Native peoples, it was heated in a number of ways. One method was to heat it in a wooden trough with hot stones. As the spruce gum melted easily, great temperature was not required. Stone and pottery containers were also used. Another method was to boil water in a bark container and drop in the spruce gum, which melted and floated on top of the water in such a consistency that it could be skimmed off with a bark spoon or dipper. Chips and dirt were skimmed off the hot gum with a strip of bark or a flat stick.
Tempering, done after the gum was melted, consisted of adding animal fat and a little finely powdered charcoal. The mixture was then tested by dipping a strip of bark into it and then into cold water. The strip was bent to see if it cracked the spruce gum; if it did, too much tempering material had been added and more gum was required. If no cracking occurred, the gum on the strip was held in the hand for a few moments to see if it became tacky or could be rubbed off the strip; if either occurred, more tempering was needed. The method of tempering had many variations. One was to remelt the gum a number of times; this darkened it and made it harder. Red ochre or vermillion were sometimes added, often together with charcoal made from the willow. Instead of spruce gum, in some areas, pine resin was used, tempered with tallow and sometimes charcoal. Eastern Native peoples sometimes used remelted spruce gum to which a little tallow had been added, making a light brown or almost transparent mixture. Most First Nations used gum that was black, or nearly so.
For repair work, when melted spruce gum could not be procured in the usual manner, hard globules and flakes of gum scraped from a fallen spruce tree were used. These could not be easily melted, so they were first chewed thoroughly until soft; then the gum was spread over a seam. This type of gum would not stick well unless it were smoothed with a glowing stick, and hence was used only in emergencies.
Spruce gum is used to seal the seams in a birchbark canoe and make it watertight. Spruce gum is the sap of the spruce tree. You can find it on the same trees that you get roots from. Where there is a wound in the tree the sap oozes out and dries to form a hard mass.
To collect the gum, scrape it off with a stick or old knife into a bucket or plastic bag. The gum has to be purified and mixed with a bit of fat (such as lard) before it is used. First melt it in an old pot until it is liquid. Then strain it through a cloth, squeezing it tight to get all the good gum out and leave the sticks, dirt and insects behind.
Mixing the right amount of fat into your gum is a bit of a magic art. If there is not enough fat, the gum will harden and crack like hard candy. If there is too much fat, it will not harden and will run out of the canoe’s seams. This all depends on the temperature at which the canoe will be used. In warm weather, you need gum with less fat so it will stay hard. In cold weather you need more fat so the gum will not crack. Native people used to use different gum mixtures for different times of the year.
To gum a canoe, you heat up the gum and fat mixture until it is liquid but not too runny. Use a stick and gather a bit of gum on the end. Blob the gum over the seam or hole you want to seal. Lick or spit on your finger and press the gum into the seam. If you don’t wet your finger it will stick to the gum. It’s hard to get gum off your hands
NOTE: The harvesting of birch bark or any building materials are much more then the physical act of collection. It touches on levels that most people have forgotten how to understand. Every step in the forest on Mother Earth is a spiritual journey that promotes connection with our surroundings, our environment, our culture, our traditions, our spirituality and ourselves. Being able to partake in this journey, the collection of birch bark, promotes positive interaction and keeps that connection to who we are alive and well.