Wood Grain

In its simplest aesthetic meaning, wood grain is the alternating regions of relatively darker and lighter wood resulting from the differing growth parameters. Wood grain is the arrangement or pattern of the fiber of a piece of wood. The pattern of grain is created when the wood is cut. A tree has rings that grow each year, specifically in the summer and spring time, called growth rings. When a tree is sawn, it is cut through the annual rings.

​

Checking

Checking is the swelling and shrinking through the seasons that causes the cracks (fissures) on the surface of the wood known as 'checking'. Splits and cracks (known as wood checks in the industry) occur when wood shrinks as it dries. Wood shrinks roughly twice as much along with the growth rings (radially) as it does across the rings. It is this uneven shrinkage that causes checks to develop.

​

Tearout

A "Type 1" cut occurs when the wood fails ahead of the tools cutting edge. If the tool is cutting against the grain of the timber, then the cut goes deeper than intended when the shaving is levered upwards by the tool. Because the failure occurs below the line the cutter is traveling on, you get tearout. Commoness of tearout or other machining defects such as fuzzy grain (tearout is most commonly caused by spiral, interlocked, or otherwise irregular grain). Generally, tearout happens when routing across the grain, turning corners or removing too much material in one pass.

​

Figured

A section of a piece of timber where a branch has come out of. These are a common feature seen in certain types of timber such as pine. Often cylindrical in shape with the timber a darker tone than the rest of the timber. 

In wood, figure refers to the appearance of wood, as seen on a longitudinal surface (side grain): a "figured wood" is not plain. The figure of a particular piece of wood is, in part, due to the cut, or to innate properties of the wood. 

Figures in wood can be caused by many things, including disruptions in the normal grain, colour and form of the wood from injury, moulds, insects and fungi. Most figured wood originates from burls/burrs, which are large, tumour-like growths found on trees.

​

Straight Grain

A straight grain describes wood grain that runs in one direction. It has very few curls or waves. A straight grain refers to wood grain that runs parallel to the axis of the tree. It does not weave or curl. Types of woods that have straight grain include cherry, hard maple and cedar.

As the name suggests, this denotes species which grow straight and parallel with the trees trunk. Straight-grained woods are generally easiest to work and machine with minimal complications.

​

Spiral Grain

Spiral grain is the helical form taken by xylem tissues in their growth along a tree trunk or limb. Sprial grain is often conspicuous in snags that have lost their bark. The cause of spiral of prevailing winds in most of the tree-growing northern hemisphere, are from the West. Combine these factors, and the westerly wind pushing on the thicker south side of the tree, year after year, causes an asymmetrical wind loading which slowly twist the tree around in the observed direction. Despite the reduction in the raw strength of the wood itself, spiral growth gives a tree greater flexibility that its straight-grained neighbours, making the tree more resistant to high winds or heavy snow loads. Some tree species grow with the grain at a slight incline, with a spiral-like pattern circling the trunk.

​

Interlocked Grain

Interlocked grain is a wood grain in which the the fibres incline in one direction in a number of annual rings and in a reverse direction in succeeding rings. Interlocked is when spiral grain goes a step further, and the spiral-grained trees change directions, and spiral back and forth throughout the trunk, alternating between between right-hand and left-hand spirals. 

Taking Spiral grain a step further, interlocked grain occurs when spiral-grained trees change directions, and spiral back and forth throughout the trunk, alternating between right-hand and left-hand spirals. Depending on the slant of the spiral, and the frequency of the directions changes, woods can be either shallowly or strongly interlocked. This change in grain direction can be seen the clearest on quarter sawn surfaces, which creates a ribbon stripe figure. Both spiral and interlocked grain can present challenges when machining and may result in tearout. 

​

Wavy Grain

Just as the name implies, this grain pattern indicates when the grain of the wood grows in a wavy fashion. This pattern is most clearly seen in flatsawn sections of wood. Wavy grain is a are figure type of wood resulting from undulating fibre growth that leads to a decorative and highly priced timber. The cause of wavy grain is curl and compression grain perpendicularly crossing the face of a board producing alternate stripes of hard and soft board fibre. The phenomenon creates a chatoyantcy in the bard varying in strength depending on the degree of compression leaving the viewed with the illusion of a three-dimensional surface. 

​

Fuzzy Grain

Species such as cottonwood are know to have large zones of reaction wood and fuzzy grain. Poor tool geometry accentuates fuzzy grain from machining low-density or reaction wood. Small rake or clearance angles or dull toes may cause tearing of fibres below the machines surface of reaction wood.

​

Irregular

This is a more ambiguous catch-all term that describes wood grain that swirls or twists in an abnormal way. Irregular grain can be due to a number of factors, such as knots, burl/burr, large branches separating from the trunk (called "crotch" wood).

​

Texture

In the most basic terms, the wood texture describes how a wood feels. Given an equal amount of sanding and smoothing operations, different woods will feel smoother than others. Some will still feel somewhat soft and rough (what is described as coarse texture), while others will feel very smooth and glassy (referred to as a fine texture). Also related to the texture itself is the uniformity of the texture. Because of the size and distribution of the pores (particularly within the early wood zone), wood can be very uneven textured. Diffuse porous woods with small pores tend to be the most evenly textured. If a wood species has very large, open pores, such as those found in Red Oak or Wenge, the finished surface will likely be grooved with tiny slits and valleys where the finish. Settled into the pores, and a pore filler will be needed to get a glassy smooth surface. But if the pores are listed as small or very small, such as the pores of hard Maple, the wood will likely be finished to a smooth and level surface, without the need for pore fillers

​

Luster

Sometimes referred to as sheen, a woods lustre is a measurement of how much light it will reflect. Typically, any wood may appear to have a high sheen if a glossy finishing agent has been applied over the top of the wood; however, some wood species are able to take on a very high polish without  any sort of finish applied to them at all . Ebonies and many Rosewoods are know for their high natural lustre.

​

Quarter Sawn

Quarter sawn timber is defined as wood where the angular growth rings intersect the face of the board at a 60 to 90 degree angle. When cutting this timber at the sawmill, each log is sawn at a radial angle into four quarters, hence the name. Dramatice flecking is also present in red oak and white oak.

Some advantages of quarter sawn timber: shrinks and swell less in width, cups, surface-checks, and splits less in seasoning and in use. Raised grain caused by separation in annual rings does not become as pronounced. A board with growth rings running roughly parallel - usually in arches - relative to the face of the boards is called a plain - sawn (or flat-sawn) board. If the growth rings are at a steep angle relative to the face, the board is said to have quarter sawn grain.

​

​

​

​

​

​

​

​

​

​

​

​

​

​

​

Quarter sawn timber produces much less usable timber than plain-sawn timber, making it more expensive. It is often still sought after because it is more stable. It is less likely to cup or twist and there are fewer surface checks and splits. It also wears more evenly.

Quarter sawn timber typically does not warp or twist. quarter sawing or quartersawing is a woodworking process that produces quarter sawn or quarter-cut boards in the rip cutting of logs into timber. The resulting timber can also be called radially-sawn or simply quartered.

​

Flat Sawn

Plain sawn timber is also commonly referred to as "Flat sawn". This is the most common and widely used method of sawing. Plain sawn timber is produced by making the first cut on a tangent to the circumference of the log. Each additional cut is then made parallel to the one before.

Flat sawn timber is the most common cut of timber used in hardwood flooring. The flat sawn grain is less dimensionally stable than other costs and can cup more easily. Quarter sawn timber is produced when the lot is cut into four quarters (hence the name), then each quarter is flat-sawn.

​

Burr / Burl

A burr is made up of a tree's bud tissue that has not sprouted into foliage or grown into a twig. It has a woody or barked surface. As a burr grows, it incorporates the tree's undeveloped buds that surround it and folds them into its expanding form. Most burrs, especially layered burrs , are not particularly valuable. On the other hand a larger eyed burr in good condition should bring £25 to £200 depending on size, species and conditions. These burrs are found around tree trunk bases or where branches have been broken. They are also found in underground tree tissue (roots). Burrs are not unique to just one species of tree.

The grain pattern in burr wood slabs are incredible. Often, the most burrley pieces are old growth, meaning they have no sapwood and are considerably older than second or new growth pieces. These old growth pieces have distinct coloration, burrley grain, and could also have mineral staining or voids.

Burrs are hard, wood protuberances that grow on the roots, trunk or branches of nearly every tree species. Their growth is chaotic, and they feature irregular grain patterns that do not match the grain of the rest of the tree. Burrs continue to grow as the tee grows. They can span from several inches to several feet across. They do not harm the tree directly, but there is some scientific evidence that burrs make a tree more susceptible to insects and disease. Burrs are prized among woodworkers due to their unusual swirling grain pattern, and burr wood is often used in the making of musical instruments. Burrs can be identified by Sight and touch,   1. Walk near trees to observe their roots, normal roots grow outwards from the trunk and have a long, snakelike appearance. Look for roots that are bowed or rounded. This is a characteristic of root burr.   2.Examine the tree trunks. Observe any rounded growths projecting from or surrounding the trunk that have no protruding limbs or twigs. Look for growths that are darker in colour than the rest of the bark. These qualities indicate burrs.  3. Touch the bark on the suspected burr if you can reach it. Touch the bark on a normal section of the trunk and compare the feel. Burr bark usually has a rougher feeling than normal bark.  4. Look up and observe the tree branches. Watch for round growths that do not have limbs or twigs growing fro them. Watch for growths that are darker in colour than the surrounding bark. These are signs of a branch burr. Branch burrs are much less common than root or trunk burrs.  By Kathryn Jones.

​

A Burr (British English) or Burl (American English) is a tree growth in which the grain has grown in a deformed manner. It is commonly found in the form of a rounded outgrowth on a tree trunk or branch that is filled with small knots from dormant buds.

​

​

​

 

 

 

 

 

 

 

 

 

 

 

 

Knots

Knots are visible imperfections in wood grain that are circular and darker than the surrounding area. When a board is cut vertically from a tree trunk, the knot will resemble a circle of abnormal wood that was once the base connection of a branch to the tree trunk but has been grown around by the rest of the grain. The two types of knots are:

• Closed knot. Flat face with no openings in the surface.

• Open knot may occur as a very small pin-sized hole to a large gaping hole.

• Unsound knot. A portion of the wood will move readily. Also known as a loose knot.

• Sound Knot. Also known as a tight knot. Solid, with no portion moveable. As hard as surrounding wood with no signs of decay.

• Pin Knot. Small, sound, and tight.

• Knot cluster. A grouping of usually small knots.

Knots occur in wood when a branch gets embedded in the tree trunk as it increases in diameter. When the branch is living, it creates what is known as a tight knot or inter grown knot. The embedded branch continues to grow with the rest of the tree. Tight knots are firmly attached to the tee. Wood knots weaken wood strength. In fact, knots materially affect cracking (known in the UK as "shakes"), warping, and the ease of working the timber. They are defects that lower the timber's value for structural purposes where strength is critical.

Why are knots in wood so hard? As a result, knots form around these branches, and trunk material continues to build up as the tree expands further. The wood in the knot is usually very tough (even harder than the surrounding wood), and therefore, forms a hard bulge around the branch emerging from its centre.

What is a big knot on a tree called? On some trees, these hard, woody outgrowths - called "Burr's" or "Burl's" - stand out on an otherwise clear trunk like a gaiter. On other trees, the whole trunk might be covered with these masses. If you've never noticed these growths before, don't be alarmed, they cause little or no harm to the tree.

Shake: A shake is when the grain between the wood growth rings separates. Shakes can occur on the face of a board or below the surface.

Split: A split is a crack in a piece of wood that goes all the way through the board.

​

Crotch Wood

How does crotch form? When branches meet and form a "Y" shape, the tree is limited on its space to grow. Why is it called crotch? Crotch is derived from crutch; it "was first used in 1539 to refer to a forked stick used as a farm implement". This region of the body is also described with other terms such as groin.

The crotch is a portion of the wooden slab where patterns are left from two branches that have met and given the wood a feather pattern. 

​

Drying Wood by Eric Meier

Allowing timber to passively sit at a given humidity level in order to obtain a desired EMC (air-drying) may be the simplest and least expensive method of seasoning wood, but it is also the very slowest. Drying times can vary significantly depending upon wood species, initial moisture level, timber thickness, density, ambient conditions, and processing techniques.

Drying Times and Kilns

The traditional rule-of-thumb for air-drying timber is to allow one year of drying time per inch of wood thickness, this adage obviously only takes a few of the aforementioned variables into account, but its at least a rough starting point in understanding the time investment required in order to properly air-dry timber. In situations where green wood is to be processed into usable boards, Especially in the case of thicker timber), a kiln is frequently used to control the drying process. While there are various types of kilns used to dry timber the basic premise is usually the same: a large insulated chamber or rim is used to balance and control humidity, temperature and airflow to safely and efficiently bring wood down to an acceptable moisture content. The main advantage of a kiln in that with the increased temperature and air flow - all while carefully maintaining and controlling the ambient humidity - the wood can be dried much more evenly, and its this uniformity in drying that allows it to also dry the wood quickly - simultaneously avoiding the drying defects usually associated with rapid, uneven drying.

Drying Effect

Kiln drying may also introduce internal stresses into the wood - particularly if an improper kiln schedule is used, or if corrective measures are not employed - resulting in a condition known as case-hardening. This defect is caused when the outer shell begins to dry faster than the core: the shell tries to shrink, but is inhibited by the still -wet core. If the moisture difference between the core and the shell is too great, the shell can dry in a stretched condition. Later, as the core eventually begins to dry and shrink, the condition is reversed, and the stretched shell prohibits the core from completely shrinking. In extreme instances of case-hardening, the core cans split and check in an irreversible condition called honeycombing. Kiln drying woods elevated temperatures also has many other secondary effects as well, such as killing powder post beetles (a destructive wood pest) in all stages of their development. However, it can also cause some woods - such as black Walnut - to loose the vibrancy of their heartwood colours, resulting in a more uniform and/or washed-out appearance. For most woodworkers, running their own kiln to quickly dry timber may be impractical or excessive. In most instances, simply storing project timber at a targeted humidity level is the best option to ensure it will be at the correct EMC when building time comes. However, in some cases, such as when processing logs or other green wood into timber, a more meticulous procedure will need to be followed.

Home Air-Drying Tips

• Process logs in a timely fashion. If a tree has just been cut down, or there has been recent storm damage, its best to process the logs into timber as quickly as possible: doing so will help to open up the wood and aid in drying, which can prevent rot or stain from marking the wood. Bark on whole logs can act as a natural moisture -barrier, and if left unsown, can contribute to fungal decay and deterioration.

​

Case Hardening

Case hardening describes timber that has dried too rapidly. Wood initially dries from the shell (surface), shrinking the shell and putting the core under compression. When this shell is at a low moisture content it will 'set' and resist shrinkage. The key is to add moisture quickly, as adding moisture slowly will only increase the average moisture content. Heat makes it happen faster. One way to add moisture faster is to cool the timber a bit before steaming. Case hardening does not go away with time.

Keeping the correct temperature is key to preventing case hardening. You can initially set the temperature 10 degrees above if you have a lot of surface moisture on your produce from incomplete drying after preparing for dehydrating or natural moisture from cut produce.

​

Xylem Tissue

Xylem, plant vascular tissue that conveys water and dissolved minerals from the roots to the rest of the plant and also provides physical support. Xylem tissue consists of a variety of specialised, water-conducting cells known a tracheary elements.

Xylem consists of dead cells. The cells that make up the xylem are adapted to their function. They lose their end walls so the Xylem forms a continuous, hollow tube. They become strengthened by a substance called lignin.

​

Hard Wood

The most common types of hardwoods include Oak, Teak, Sapele, Iroko and Meranti. As these grow at a much slower rate and require longer drying times, these factors drive up the cost of the Wood. Hardwoods tend to be much more resilient than softwoods and are often reserved for projects that require maximum durability.

The best hardwood floors are made with wood species that are readily available - and you guessed it - very hard. Oak, maple and cherry flooring are all good choices. Other species include bamboo (which is actually a grass), Walnut, ash and mahogany.

Hard wood timber originates from an angiosperm tree, a tree type with seeds that are usually enclosed, like pods or shells. The common examples of hardwoods are also, mahogany, maple, elm, sycamore and oak.

Hardwood is so expensive due to cutting down all of the old growth timber has made it to where there are far less large trees. This means less hardwood over all. This has resulted in major increases in prices for all hardwood products. the cost. of hardwood flooring has increased drastically since the year 2000 (written by March 2020).

In woodworking terminology, the term "hardwood" is not strictly a term referring to hardness, but rather to the botanical designation of the trees from which the wood comes. In short, hardwoods are angiosperms (flowering plants) while soft woods are classified as cone bearing plants (conifers). For practicality sake, it just so happens that most hardwoods happen to yield fairly hard wood, so the name "hardwoods" is generally applied, though not always strictly correct. (For instance, Balsa is a flowering plant, and is technically considered a hardwood).

Anatomically, the most noticeable element of all hardwoods is the presence of pores, sometimes called vessels. These vessels usually appear as small openings in the wood when viewing the end grain. Noting the size, arrangement, and contents of the  pores is generally the first step in attempting to identify a hardwood.

The hardwoods of the world exhibit a dazzling array of ingrain patterns and intricate motifs: and its in this complexity that the challenge, (and joy) of wood identification really comes alive. An unknown hardwood sample could be just about anything under the sun, yet as each anatomical feature is considered, anything is narrowed down to something.

That is to say, throughout the identification process, the more observations that can be made and classified about a hardwood sample, the more and more the field of possible candidates narrows. Ultimately, the point is reached where no further where no further refinements can be recorded, and either  a clear identification emerges, or a handful of possibilities remain.

Balsa wood, which is classified as a hardwood is one of the lightest, least dense woods you can find. There's no density or weight requirement to be classified as a hardwood, its all to do with reproduction.

​

Soft Wood

The main difference between hardwood and softwoods is that the structure of hardwood lack resin canals, whereas softwoods lack pores. Softwoods usually grow quicker than hardwoods and are cheaper, softer to work. Common examples of softwood include: pine, fir, spruce, larch and cedar.

Softwood is a collective term for the wood which is produced by coniferous trees, almost all of which are evergreen. Conifers are cone bearing trees, as opposed to the more leafy deciduous trees lie oak and maple, both of which produce hardwoods. Some of the most common trees for producing softwoods are cedars, pines and firs, all of which grow extensively across the Northern Hemisphere.

Softwoods are generally light, open-grained woods which are used for a wide range of applications inside the home.

Softwoods are special because they don't lose their needles. Softwoods have needles instead of leaves. Softwoods grow faster than hardwoods so are cheaper.

When sawn and planed they tend to be light / pale in colour. One unique property of softwoods is that they do not contain pores like hardwoods do. When attempting to identify any softwood, the first thing to look for is resin canals. The world of conifers is much more limited. Softwoods are much simpler than hardwoods in their anatomical features so there are far fewer clues to help identify them. Consequently, macroscopic softwood identification is usually less conclusive, and many times will only result in more board or generic identification, such as, pine or spruce, rather than determining an exact species.

The primary distinguishing feature between softwoods and hardwoods is that softwood species lack pores. So upon initial examination of an unknown wood sample, the most immediate detail to note is whether or not the ingrain section has numerous circular openings - commonly referred to as vessels or pores.

Because softwoods are poreless another conspicuous and easily recognisable feature is used to quickly make broad distinctions between conifers.

Resin canals, sometimes referred to as resin ducts, are unique to conifers, they are technically not individual cells, but are actually open, tube-like spaces bordered by special cells that have the ability to secrete pitch or resin into there neighbouring opening (Canal).

In short, Softwoods are conifers (cone-bearing plants) while hardwoods are classified as flowering plants (angiosperms). For practicality's sake, it just so happens that most conifers happen to yield fairly soft wood, so the name "softwood" is - general applied, through not always strictly correct.

​

Cupping

Excess moisture is the culprit when it comes to hardwood cupping. This happens when the humidity level is high, when the timbers absorb too much moisture from water leaks and spills or even by cleaning in the wrong manner.

Cupped hardwood surfaces may flatten over time if you can remove the excess moisture. However, it will take a lot of time, even a season to fix the cupped hardwood. Otherwise, you need to replace the cupped hardwood with a new one to fix the issues. 

The simplest way to think of wood floor cupping is to imagine the edges of each plank sticking up higher than the centres. It ends up looking a little like an accordion. If you imagine a picture of a child drawing a boat in the water, then the water will give you a good idea of what a cupped floor looks like.

To truly fix cupped hardwood floors, you must get to the source of the water damage. Once you've addressed that, you can try to get your wood floors back to their original state. For minor cupping, the fix might be as simple as returning the room to its normal humidity levels with a dehumidifier.

​

​

​

​

​

​

​

​

​

​

​

​

​

​

Medullary Rays

Medullary rays are cellular structures found in some species of wood. They appear as radial planer structures, perpendicular to the growth rings, which are visible to the naked eye. In a transverse section they appear as radiating lines from the centre of the log.

Medullary rays (also referred to as Pith rays, Oak fire or tiger stripes) are thin horizontal rays that extend radially from the core of the tree towards the bark. They can appear very shiny and vary in heights; from a few cells in some species to four or more inches in Oak.

These rays are caused by plant cells which extend vertically at an angle that is perpendicular to the tree's vertical cells or growth rings as they are more commonly known. These ribbon like cells allow the conveyance of sap through the trunk, making them an essential part of the growing process of the tree.

All trees have Medullary Rays, as it is the most pronounced in White and Red Oak and when these species are quartersawn, the rays manifest themselves across the face of the timber like brush strokes.

Wood rays, are stripes of short horizontal cells that extend in a radial direction across

​

​

​

​