Wood grain in the context of "Anisotropic"

Anisotropy (/ˌænaɪˈsɒtrəpi, ˌænɪ-/) is the structural property of non-uniformity in different directions, as opposed to isotropy. An anisotropic object or pattern has properties that differ according to direction of measurement. For example, many materials exhibit very different physical or mechanical properties when measured along different axes, e.g. absorbance, refractive index, conductivity, and tensile strength.

An example of anisotropy is light coming through a polarizer. Another is wood, which is easier to split along its grain than across it because of the directional non-uniformity of the grain (the grain is the same in one direction, not all directions).

Woodcut is a relief printing technique in printmaking. An artist carves an image into the surface of a block of wood—typically with gouges—leaving the printing parts level with the surface while removing the non-printing parts. Areas that the artist cuts away carry no ink, while characters or images at surface level carry the ink to produce the print. The block is cut along the wood grain (unlike wood engraving, where the block is cut in the end-grain). The surface is covered with ink by rolling over the surface with an ink-covered roller (brayer), leaving ink upon the flat surface but not in the non-printing areas.

Multiple colours can be printed by keying the paper to a frame around the woodblocks (using a different block for each colour). The art of carving the woodcut can be called xylography, but this is rarely used in English for images alone, although that term and xylographic are used in connection with block books, which are small books containing text and images in the same block. They became popular in Europe during the latter half of the 15th century. A single-sheet woodcut is a woodcut presented as a single stand alone image or print, as opposed to a book illustration.

Wood engraving is a printmaking technique, in which an artist works an image into a block of wood. Functionally a variety of woodcut, it uses relief printing, where the artist applies ink to the face of the block and prints using relatively low pressure. By contrast, ordinary engraving, like etching, uses a metal plate for the matrix and is printed by the intaglio method, where the ink fills the valleys, the removed areas. As a result of the relatively lower pressure used to print, the blocks for wood engravings deteriorate less quickly than the copper plates of engravings, and have a distinctive white-on-black character.

Thomas Bewick developed the wood engraving technique in Great Britain at the end of the 18th century. His work differed from earlier woodcuts in two key ways. First, rather than using woodcarving tools such as knives, Bewick used an engraver's burin (graver). With this, he could create thin delicate lines, often creating large dark areas in the composition. Second, wood engraving traditionally uses the wood's end grain—while the older technique used the softer side grain. The resulting increased hardness and durability facilitated more detailed images.

A plank is timber that is flat, elongated, and rectangular with parallel faces that are higher and longer than wide. Used primarily in carpentry, planks are critical in the construction of ships, houses, bridges, and many other structures. Planks also serve as supports to form shelves and tables.

Usually made from timber, sawed so that the grain runs along the length, planks are usually more than 1+1⁄2 in (38 mm) thick, and are generally wider than 2+1⁄2 in (64 mm). Planks are often used as a work surface on elevated scaffolding, and need to be thick enough to provide strength without breaking when walked on. In the United States, planks can be any length and are generally a minimum of 2×8 (1+1⁄2 in × 7+1⁄4 in or 38 mm × 184 mm), but planks that are 2×10 (1+1⁄2 in × 9+1⁄4 in or 38 mm × 235 mm) and 2×12 (1+1⁄2 in × 11+1⁄4 in or 38 mm × 286 mm) are more commonly stocked by lumber retailers. Timber is categorized as a board if its width is less than 2+1⁄2 in (64 mm), and its thickness is less than 1+1⁄2 in (38 mm). In Germany, the national norm (DIN 68252) stipulates that the thickness of a plank (termed Bohle) must be 40 mm minimum.

Wood splitting (riving, cleaving) is an ancient technique used in carpentry to make lumber for making wooden objects, some basket weaving, and to make firewood. Unlike wood sawing, the wood is split along the grain using tools such as a hammer and wedges, splitting maul, cleaving axe, side knife, or froe.