European birch is one of those woods that is very plain — except when it isn’t. Some of the distinctive patterns yielded include flame and curly figures. Another figure of note is Karelian birch, known also as Karelian burl and Masur birch.
Karelian burl grows in a fairly small area in mid- to east Finland. Although birch in general grows all over Finland, the burl figuration is due to certain landscape features and very unique soils, which are limited to a small area of Karelia. It grows among plain birch as well as mixed with spruce, pine and elder. It is never found in complete stands or in plots.
It is necessary to wait for the winter season to harvest the trees because the leaves have to turn yellow, red and brown to show that sap has left the trunk completely. Otherwise, logs will have sap-discolorations after peeling. Also, the ground has to be deeply frozen in order to extract the logs from difficult landscape with small trucks and machinery or, what is still a usual procedure, with horses.
Although there are cases where the Karelian burl can be completely burled in the full length up to 10 feet, that is very seldom. Mostly the logs have got parts of 2 feet to 3 feet burled, then plain again, then burled again. Careful examination of the bark can help determine the amount of burl prior to cutting. The bark shows a kind of bursting and cracking, as if the burl-character forces the volume out of the logs.
Betula alba of the Family Betulaceae
Karelian birch, karelian burl, Norway burl birch, European birch, Finland birch, flamey birch, birch burl, alpine burl
The average height of European birch trees is 60 to 70 feet. Weight varies from 37 to 43 pounds per cubic foot, with an average weight of 41 pounds per cubic foot and a specific gravity of 0.66
Karelian birch burl requires slow, careful drying to avoid tension checking and warping.
The wood works well with all varieties of tools.
It requires preboring. Experts recommend using a reduced angle when planing in order to avoid tearing.
Felling is tightly controlled and Finnish authorities insist on strict felling quota to only a special number of listed farmers and timber men in Karelia. Because of this careful system and continued replanting, a healthy environment is maintained and supplies can be called sustainable.
In addition to specialty items, other uses for Karelian birch include high-quality architectural woodwork and furniture. Bookmatched Karelian birch is a very beautiful, benign wood and it works well.
One of the first things that woodworkers mention when talking about Karelian birch is that there are other species found with the similar type of figure in different parts of the world, such as maple, walnut, cherry and oak. And these rarities are often described as ‘Karelian’ due to the sound ingrown bark, which creates a pleasing figure type that is much more common with the birch found in the special areas of Finland.