Design

Wood Color

Wood colors can range widely. One should remember that wood color can vary not only from one species to another but can have several tens of tonal correlations within one species. Wood is colored by tanning agents contained in its cellular tissue. Wood species of warm colors prevail (yellow, ocherous, red, red-brown, brown), but there are also green, blue, violet, and black species that are considered exotic in our country.

Wood Shine

Wood shine is the ability of wood to reflect luminous flux from its surface in a certain direction. Different species shine in a different way. Shining is significant in beech, maple, chenar, robinia. Wood shine depends not only on the availability and size of wood rays but also on the character of their location on crossings: the larger are wood rays (in oak for instance) and the denser the wood, i.e. the higher is concentration of wood rays (in maple for example), the more wood will shine. Shadow-light play in one species is seen only on longitudinal stem splitting, in others – on all splittings. It influences greatly decorative wood qualities making it more or less expressive; therefore, wood shine is taken into account when designing mosaic sets.

Wood Texture

Wood texture is natural pattern of wood grain on a processed surface dependent on the peculiarities of its structure. Texture depends on the peculiarities of anatomic structure of individual species of wood and cut direction. It is defined by the width of annual rings, the difference of earlywood and latewood, the availability of wood rays, large tracheas, abnormal grain setting (wavy or interwoven).

Wood Scent

Wood scent depends on the quantity of essential oils, tars, and tanning agents. Newly cut wood and one immediately after its mechanical processing has powerful scent. Coniferous wood has more powerful scent than hardwood. Spruce and pine have turpentine scent as coniferous trees. Oak scents with tanning agents, guaiacum and palisander with vanilla. One can define wood species by its scent.

Macrostructure

Macrostructure is characterized by the width of annual rings defined by the number of rings per 1cm of the section measured in radial direction on a crosscut.

Humidity

Wood humidity (absolute) is percentage-expressed ratio of humidity mass in the given wood volume to the absolutely dry wood mass.

Shrinkage

Shrinkage is the reduction of linear dimensions and volume of wood while drying. Wood shrinkage starts after completion of free moisture withdrawal and beginning of bound moisture withdrawal. Shrinkage is not the same in different directions. Average total linear shrinkage in the tangential direction is 6…10%, in radial – 3…5 %, along the grain – 0.1…0.3%.

Inner stresses

Stresses not caused by external force are called inner stresses. Appearing of stresses while wood drying is caused by inhomogeneous distribution of moisture. If tensile stresses reach wood maximum cross-grain strength cracks may appear: on wood surface when drying starts and inside when it ends. Inner stresses remain in dried material and cause changes of component size and shape during mechanical processing of wood. Residual stresses are relieved by additional sawn wood processing (steam humidification).

Warping

Wood drying and wetting cause the change of board cross section shape. Such shape changing is called warping. It can be cupping or bowing. Cupping is the change of board section shape. It is caused by shrinkage difference in radial and tangential directions. Heart wood boards reduce their size towards edges: boards with external part closer to tangential direction shrink more than inner ones of radial direction. The closer a board is to the heart the more it warps. Warping can be prevented by quality laying, drying, and storage of wood.

Swelling of Wood

Swelling is the increase of wood linear dimensions and volume with increasing of its bound moisture. Swelling takes place when moisture reaches the hydroscopic limit. Free moisture increase does not result in swelling. Like shrinkage, most swelling occurs in tangential direction along the grain, the least one - across the grain.

Water Absorption

Water absorption is the ability of wood to absorb dropping-liquid moisture by its porous structure. Water absorption occurs during water and wood immediate contact. It increases the content of both bound and free moisture.

Density

Wood density depends on its humidity. Density values are always compared for the united humidity value of 12%. Wood density and strength are closely connected. Heavier wood is usually firmer. Density values can vary greatly.