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Wood \u2013 the ecologic material<\/h2>\n\t\t<\/span>\n\t<\/div>[vc_column_text]The basic elements of timber are : coal (49.5% ), oxygen (43.8 % ), hydrogen (6.0%) , nitrogen ( 0.2% ) and others. The main compounds of wood are cellulose (about 45%) , hemicellulose ( 30% ) and lignin (about 20%). In addition, there are also sugar, protein , starch , tannins , essential oils , rubber and minerals \u00a0in wood which, when burnt, become ash . The chemical composition of ash depends on the type of tree , climate , soil , etc[\/vc_column_text]\n\t
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Durability of wood<\/h2>\n\t\t<\/span>\n\t<\/div>[vc_column_text]A sample hardness measured by the Janka\u2019s hardness test(using a 1 sq. cm cross-section metal ball) at 15 % moisture content , for certain species of wood is , from softest to hardest :<\/p>\n
\n
Pine – 28-30 MPa ,<\/li>\n
Alder – 43 MPa ,<\/li>\n
Birch – 48 MPa ,<\/li>\n
Oak – 66-77 MPa \u00a0a(higher value for the so-called heartwood )<\/li>\n
Nut – 72 MPa ,<\/li>\n
Ash – 72-75 MPa ,<\/li>\n
Beech – 78 MPa ,<\/li>\n<\/ul>\n
Hard wood is often most resistant to abrasion. This feature is important when choosing the wood as a material.[\/vc_column_text]\n\t
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The color of wood<\/h2>\n\t\t<\/span>\n\t<\/div>[vc_column_text]In the wood of our tree species there are six main types of color :<\/p>\n
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The color close to white – fir , spruce , aspen , hornbeam , beech , maple , sycamore<\/li>\n
The yellow color – birch, stone pine<\/li>\n
The color brown – oak, ash , elm<\/li>\n
Different shades of red – yew, larch , pine , cherry, plum<\/li>\n
A greenish color – locust<\/li>\n
The color close to black – walnut, ebony<\/li>\n<\/ul>\n
The color of the wood , except its species may also be affected by climatic conditions and, to a lesser extent, soil.<\/p>\n
The sapwood is uniform throughout the cross-section of bright color with darker colored layer outlining the late wood and a lighter layer of the early wood . In the wood of heartwood species there is a clear difference between the brightly colored \u00a0sapwood and darker heartwood.<\/p>\n
In the northern part of the temperate climate there is dominance of the species with the brightly colored wood (spruce , birch , aspen) . In the southern part of the zone there are species of trees whose wood has a larger variety of colors and shades (oak , ash, plum , larch ). Finally, the largest range of colors and shades of the wood can be found in the subtropics ( green and black ebony tree magenta ).<\/p>\n
The color of wood changes because of light and the weather. \u00a0The alder takes a red brick colour in a few hours after being cut off .The reddish yew wood takes on a purple hue with time . The prolonged exposure to water makes the tannin-containing wood take on the characteristic color ( the oak blackens). Finally, various atmospheric conditions make the majority of wood species go grey.[\/vc_column_text][\/vc_column][\/vc_row]<\/p>\n","protected":false},"excerpt":{"rendered":"
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