The following terms may come in handy when discussing your timber requirements.
Annual Ring of Growth - measurement of an average number of annual rings at either one end or the other end of a piece over a 3” line. The line is usually measured along the centre three inches of the longest radial line which can be drawn along the piece.
Bark Pocket is a well-defined opening containing bark between the rings of annual growth which develops during the growth of a tree.
Board Foot – (BF) is a unit of lumber measurement one foot long, one foot wide, and one inch thick. Clear softwood and North American hardwoods are sold in cost “per thousand board feet”. 1,000 BF = 2.36 cubic metres and 1 cubic metre = 424 BF.
Borer Holes holes in timber caused by boring insects (or their larvae), either in the living tree or after felling or sawing. Three sizes are normally recognised. Pin (and Needle) are holes not over 1/16 inch in diameter, usually about 1/32 inch or less, sometimes stained round the edges. Shot Holes are over 1/16 inch but not exceeding 1/8 in diameter, if the edges of the holes are not stained they are known as unstained shot holes.Large Borer Holes (Grub Holes) are holes over 1/8 inch in diameter, usually average 1/4 inch in diameter.
Bow - see Warp.
Checks are a separation of the wood across the rings of annual growth of a piece, normally occurring lengthwise, and usually as a result of seasoning (drying).
Clear is a term used to describe higher grades of timber, which are sound and relatively free of blemishes.
Clear Face Cutting (MGR)
clear of all defects on the face graded (other than bright sapwood when allowed in specific rules for any grade); the reverse face must not be worse than as defined under sound face cutting.
Collapse irregular or excessive shrinkage during the drying of timber.
Compression Wood is wood formed with somewhat differing fibre characteristics due to abnormal stresses in the tree. It will tend to cause timber to bend or warp because it is harder and it may also be darker in colour.
Conditioning is adjusting the moisture content of wood.
Cross Grain – (short grain) is grain not parallel with the axis of a piece. It may be either diagonal or spiral grain, or a combination of the two. If one looks at the vertical grain face or edge of a piece of timber, the “stripes” will run a slight
angle to the edge line of the piece.
Cut Stock is clear pieces that have been ripped and cross cut from shop grade timber, such as stiles, rails, muntins, window sash and many others, intended for further manufacturing. A common form of cut stock sold in the UK is 2”x 4” or 11/2”x 4” x7’ for door stiles.
Cutting - a rectangular portion of a piece of sawn timber that could be obtained by cross-cutting, ripping or both.
Decay - includes Wet Rot and Dry Rot – it is the disintegration of wood resulting from the action of wood destroying fungi or bacteria. It is usually accompanied by discolouration even in the early stages of attack. Affected wood should not be considered for structural or constructional work.
Diamonding - a term applied to uneven shrinkage that causes a square to distort to diamond shape.
There are two ways of drying timber:
i) Natural ‘Air’ Drying
ii) Kiln Drying
Air Drying - This is carried out by stacking pieces of timber on top of each other separated by lathes or sticks to allow air to circulate. Alternatively, by placing timber at right angles to each other creating gaps for air circulation. This method of drying can take some considerable time.
Kiln Drying - This is the method used to speed up the drying process using any form of dryer, such as kilning chamber or de-humidifier
Why do we dry timber? Look at any felled tree and the first thing you notice is how wet it is. When it’s sawn and is still wet, it will not twist, warp or bend. However, many timbers in this state decay rapidly. When you dry timber, this problem is elevated. If you were to manufacture any goods from wet timber, there is a very good chanceit will become distorted, shrink, split and generally be unusable if it dries in the wrong conditions. By drying timber in the correct manner, tension within the timber which causes many defects is relieved, creating well dried timber in good condition ready for manufacturing.
Timber and moisture - Timber is “hygroscopic”. This means it will take in and give up moisture depending on the condition in which it is placed. It is therefore most important that we have timber at the right “moisture content” before it is put in-situ. The most recent standard for moisture content in general joinery is as follows:BSEN 942 1996 Timber & Joinery
General Clarification of Timber Quality
External joinery: 12–19% M/C
Internal joinery/Unheated rooms: 12–16% M/C
For heated buildings providing room temperature of 12 degrees C to 21 degrees C: 9–13% M/C
For heated buildings providing room temperature of 21 degrees C: 6–10% M/C
There is a variance of maximum 3% M/C allowable within the above. (M/C - Moisture Content.)
Edges Eased - slightly rounded surfacing of edges to remove sharp corners.
Edges Square - Square free from wane without eased edges.
Flat Sawn otherwise known as 'Bastard Sawn'. Timber cut tangentially to the annual rings giving an irregular pattern formed by the annual rings.
Grading Associations various bodies designed to promote uniform quality in timber products. Standards are internationally accepted, and sufficient for most applications unless otherwise stated:
R List – (US) Pacific Lumber Inspection Bureau, RULES FOR EXPORT GRADING.
WCLIB – (US) West Coast Lumber Inspection Bureau.
WWPA – (US) Western Wood Products Association.
MTIB – Malaysian Timber Industry Board.
NHLA – (US) National Hardwood Lumber Association.
NLGA – (Canada) National Lumber Grades Authority.
SPIB – (US) Southern Pine Inspection Bureau.
Grain - the direction, size, arrangement and appearance of the fibres in wood:
Flat Grain (FG) is timber sawn approximately parallel to the annual growth rings so that all or some of the rings form an angle of less than 45 degrees with the surface of the piece. The surface of the piece will show the florets or patterns of the grain.
Mixed Grain (MG) mixed grain is a combination of both flat and vertical grain pieces within a parcel of timber.
Vertical Grain (VG) also known as edge grain, is timber sawn at approximately right angles (“quarter sawn”) to the annual growth rings so that the rings form an angle of at least 45 degrees with the surface of the piece. The end of the piece will appear to have vertical lines running across the piece and the surface will have long, relatively
straight vertical lines running from top to bottom.
Raised Grain is an unevenness between springwood and summerwood on the surface of dressed timber. If you run a hand over the wide face of a piece of surfaced timber the darker grain areas will be slightly raised.
Slope of Grain is the deviation of the line of fibres from a straight line parallel to the sides of the piece.
Torn Grain is an irregularity in the surface of a piece where wood has been torn or broken out by surfacing.
Hardwoods conventional terms used to denote the timber of broad-leafed trees belonging to the botanical group, the Angiosperms.
Heart a term applied to the central portion of a log including the pith and the adjacent wood which may be defective.
Hit or Miss means a piece after machining may be completely surfaced, partly surfaced or entirely rough depending upon the accuracy of the machine. Scantness may be 1/16”.
Honeycomb the development of checks in the interior of a piece of wood due to drying stresses, often not visible at the surface. The defect occurs when thick timber is dried too quickly in a kiln.
Inbark is bark enclosed in the stem of the tree by later growth, and exposed by conversion.
Interlocked Grain - strongly irregular fibres running in different directions. This will cause problems if wood is further machined as it may then distort.
Kiln Dried - all North American hardwoods and softwoods (with the exception of cedar) must be kiln dried prior to arrival in the EC. There are several advantages to using dry timber. It is stronger and holds nails better than green; it is more stable and also minimises future warping; it is less subject to stain, decay and insect attack and is easier to paint and treat with preservatives.
Small knot is not over 3/4” in diameter.
Medium knot is not over 11/2” diameter.
Large knot is over 11/2” diameter.
Pin knot is not over 1/2” diameter.
Sound knot contains no decay. It may be red or black.
Unsound knot contains decay.
Distinction is also made between the various forms of knot:
Round & Oval Knots - knots cut more or less right across and appearing on face, edge or arris (corner).
Splay Knots - knots cut lengthwise on the face, widening out towards the arris and partly showing on the edge.
Spike Knots - knots cut lengthwise parallel to its axis, having an elongated shape finishing before it reaches the arris.
Machine Bite is a depressed cut of the machine knives at the end of the piece.
Machine Burn is a darkening of the wood due to overheating by machine knives or rolls when pieces are stopped by the machine.
Merch - construction grade timbers, generally from 8”x8” to 16”x16” in lengths of 16’-40’.
Moisture Content - the weight of water in wood expressed in percentage of the weight of oven dry wood. Shipping dry wood should range from 14% to 20%.
Mould a fine vegetable growth, or mildew, that forms on wood in damp stagnant atmospheres. It is the least harmful type of fungus and is usually confined to the surface of wood.
Occasional - used in grade descriptions to mean not more than 10% of the pieces in a parcel or shipment.
Pitch is an accumulation of resinous material:
Pitch Pocket is a well-defined opening containing pitch between the rings of annual growth which develops during the growth of the tree.
Pitch Streak is a well-defined accumulation of pitch in the wood cells in a more or less regular streak. It should not be confused with dark grain.
Primary Sawmill processes the logs from the time they are harvested, de-barked, cut into lumber and graded for sale. Sawmills may provide further processing such as kiln drying and further grading for speciality products such as export stock. One advantage of buying from a primary mill is that the wood is not re-sorted, thus higher grade pieces
are not always pulled out.
Quarter Sawn - otherwise known as Rift Sawn. Cut radially from the log, gives edge vertical or straight grained appearance.
Remanufacturing Mill - “remanners” are not involved with the felling and original processing of logs. A remanner will buy green unsorted lumber from the mill, and then perform any number of functions such as sorting, drying, resawing, ripping, surfacing, running to pattern stock or chopping as required by customers. An advantage of buying from a remanner
is that orders can be customised to suit specific needs. Because remanners buy raw material in bulk there may not be price differential between primary and reman export stock.
Ripping - using a rip saw and sawing along the grain.
RL and RW (Random Length) and (Random Width) softwoods sold as RL are understood to be a fair spread from 8’ to
20’. Softwoods sold as RW are generally understood to be a fair spread from 5’ to 14’ and/or wider. Hardwoods sold as RL are mainly 6’ (1.8m) and longer and for RW 6” (150mm) and wider. Grade or contractual agreement can allow deviation from this.
Sapwood is the outer layers of growth between the bark and the heartwood. The outer two to three inches of the sapwood is the living fibre actively involved in growth. The sapwood is the portion of the tree that is most susceptible to stain. Bright Sapwood shows no stain and is not limited in any grade except as specifically provided.
Shake is a lengthwise separation of the wood which usually occurs between or through the rings of annual growth.
Skip Dressing are areas on a piece that failed to surface clean.
Softwood conventional term used to denote the timber from trees belonging to the botanical group, the Gymnosperms. Commercial timbers of this group are practically confined to the class of Coniferae, or Conifers.
Sound Face Cutting (MGR) - a cutting that is free on both faces from decay, heart or wane, shakes,
splits or brittle heart. It will admit sound sapwood, sound knots, stain, latex faces, latex shakes, resin pockets and seasoning checks not affecting the strength of the cutting. Pin holes are also allowed
providing they are not so numerous as to adversely affect the material strength of the cutting. Some shot holes are also allowed.
Split is a separation of the wood due to the tearing apart of the wood cells. Split is usually due to large variations in temperature.
Spring - the curvature of a piece of sawn timber in the plane of its wide face.
Springwood (earlywood) - the portion of the annual growth ring formed during the early part of the yearly growth period. It is lighter in colour, less dense, and not as strong mechanically as summerwood.
Stain is a marked variation from the natural colour of the wood. Natural colour will be uniformly distributed through certain annual rings, whereas stains are usually in irregular patches. Stained wood does not reduce the strength of the piece but may be undesirable where appearance grade timber is required. Stain is usually brown or blue.
Standard - a measure of timber in softwoods.
Summerwood (latewood) - the portion of the annual growth ring formed during the latter part
of the yearly growth period. It is darker in colour, more dense and stronger mechanically than springwood.
Sundeala - wood-fibre wall board.
Tanalith - a grade of wolman salts. Applied under vacuum and pressure by soaking. Provides protection against fungi and insects with slight fire resistance. It is intended for wood exposed to the weather.
Ton - usually implies 50 cu.ft. in shipping
Uneven Grain - term applied to wood in which the growth rings are irregular in width.
Veneer - a very thin layer of wood taken from logs by either very fine saw, by slicing using a plane or by peeling or rotary cutting.
Veneer Cutting - two logs of the same species but with their veneers cut differently, will have entirely different visual characteristics. There are several ways to produce this effect:
Crown Cut - Crown Cut Veneer is produced by cutting lengthwise through the log making two sections or flitches. It is then sliced tangentially to the growth rings. This results in an oval or loop configuration in the centre of the veneer leaf with a straighter grain at the edges.
Quarter Cut - with Quarter Cut Veneer, the log is first cut lengthwise into four flitches and then sliced at right angles to the growth rings. The result is a straight grain, in the main bland, often with a pronounced striped effect.
Rotary Cut - Rotary Cut Veneer is used for reverse balancers rather than for decorative faces. The veneer is produced from a cutting action whereby the cutting knife is fixed and the log is rotated. This produces a continuous sheet of veneer with sometimes very wild characteristics.
Wane - bark or lack of wood on the edge or corner of a piece of timber.
Warp - any deviation from a true plane surface, including bow, crook, cup and twist or any combination thereof. All warp is measured at the point of greatest distance from the straight line.
Bow is a deviation flatwise from a straight line drawn from end to end of a piece, ie, if the piece is lying flat, one or both ends will be slightly lifted off the ground.
Crook is a deviation edgewise from a straight line drawn from edge to edge of a piece, ie, if the piece is lying flat, the wood will not follow a straight line all the way to the end of the piece, rather it will tend towards either the left or the right.
Cup is a deviation in the face of a piece from a straight line, ie, the edges will curve in towards or away from one another.
Twist is actual twisting of the piece around the central axis.
Weathering - resisting alternate wet and dry conditions. Chemical and mechanical discoloration and disintegration of wood surfaces due to exposure to weather, dust, light. Also fibre change due to varied moisture content.