Oak
Also called: english oak, european oak, american white oak, american red oak, quercus, japanese oak
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Oak is the timber cut from trees of the genus Quercus, a broad family of hardwoods that botanists have counted at around a hundred and fifty species worldwide, though only a handful are commonly traded as timber. Hasluck (1897) named three leading varieties in general use: English, Baltic and American white oak.
English oak against its rivals
English oak has long been treated as the standard against which other oaks are judged, and most of the older authorities compare their local or imported oaks unfavourably against it. American, or Quebec, oak was described by Hasluck (1907) as reddish brown with a coarser grain, not as strong or durable as English oak, though straighter in the grain. Rivington (1875) made much the same comparison, calling American oak's grain straighter and coarser than English oak's, but the wood itself not so strong or durable. Riga oak, imported from the Baltic, was not held in as high esteem as English oak for outdoor work or for jobs demanding great tensile or compressive strength, according to Hasluck (1907), although he added that its very prominent medullary rays, the ribbons of tissue that run out from the tree's centre across the grain, gave it an especially attractive silvery figure. Durmast oak, a variety native to France and the south of England, was judged by Tredgold (1871) to have wood neither as strong nor as firm textured as English oak, and noted for keeping its leaves later into the season than the common tree.
Silver grain and figure
Oak's most recognisable figure comes from its medullary rays, which run outward from the tree's centre across the direction of growth. Cut so the saw follows close to that ray direction, a method called quarter-sawing, the rays show on the surface as bright, flecked patches known as silver grain. Riley (1905) described British oak as light brown, showing these silvery patches when cut in a plane at right angles to the growth rings. Rivington (1875) noted that wainscot, oak imported chiefly from Holland and Riga, was valued partly because it was easily worked and could be converted, meaning sawn and prepared, in a way that showed off this silver grain to advantage. Holtzapffel (1846) described Turkey oak's timber as ornamentally mottled from what he called an abundance of silvery grain, and suggested that Sardinian oak was probably produced by the same species.
Felling, splitting and working
How and when a tree was felled mattered as much as the species. Sturt (1923) recorded that oak felled in winter always kept its bark on, while oak felled in spring split, or cleaved, especially well, a quality that suited it to the traditional craft of cleaving spokes and thin strips called laths by hand rather than sawing them. Norwegian wainscot oak was prized for being remarkably straight and easy to split. Holtzapffel (1846) recorded an old practice for exploiting this: boring a hole in the top of the tree at the start of winter and filling it with water, so the water's expansion on freezing would split the tree from top to bottom. Not every oak splits cleanly: the American chestnut-leaved oak was, as Tredgold (1871) put it, "cross-grained," yet still serviceable enough to be much used for wheel carriages.
Where oak is used
Oak has been a principal furniture wood in ordinary homes and remains a mainstay of joinery, cabinet making and building work. Green oak, meaning timber used unseasoned, straight from the tree, is still used today for exposed timber framing in some specialist new housing, while seasoned oak goes mainly to furniture making and cooperage, the craft of building barrels and casks. Cooperage depends on the heartwood being watertight, a property that comes from tyloses, small structures that block the wood's pores from the inside. The USDA (2021) records that most white oaks are suitable for tight cooperage, though it notes that many heartwood pores in chestnut oak, itself a member of the white oak group, lack these structures. White oak heartwood is also specified for planking and bent parts of boats and ships, chosen for its resistance to decay, and live oak was one of the main species used in early American shipbuilding, according to the USDA (2021). Not every oak suited every vessel: Holtzapffel (1846) judged African oak well suited to building merchant ships, but noted it was apt to splinter when struck by shot, which made it less favoured for ships of war. In North America, oak has also long served as a timber-framing wood; Benson (1988) pointed to its extensive use for timber frames in the eastern states, describing the wood as strong with a distinctive grain.