Wood is a hard, fibrous structural tissue found in the stems and roots of trees and other plants.


1   Function


The cord is a unit of measure of dry volume used to measure firewood and pulpwood in North America. A cord is the amount of wood that when well-stacked measures 4 feet high, 8 feet long, and 4 feet deep.

1.1   Paper

Pulpwood refers to timber_ with the principal use of making wood pulp for producing paper.

1.2   Fuel

Firewood is any wooden material that is gathered and used for fuel. The energy content of a measure of wood depends on the tree species. The higher the moisture content, the more energy that must be used to evaporate (boil) the water in the wood before it will burn.

1.3   Construction

Lumber (American English, = timber in the rest of the world) is wood that has been processed into beams_ and planks_.

Quarter sawn lumber is better than any other way (for furniture making or any other form of woodworking) because it is more predictable in how it will move and change with the seasons after it is properly dried. I think it’s more expensive because it actually yields less usable board feet of lumber than just flat sawn lumber.

Also different grain and figuring. Brings out interesting and beautiful grain patterns in hardwoods like maple, mahogany, walnut, etc.

2   Combustion

Wood burns in two stages: the hydrogen stage and the carbon stage. In the hydrogen stage, hydrocarbon molecules are broken and oxidise. In the carbon stage, the carbon oxidises.

The carbon stage burning is a hotter and cleaner chemical reaction than hydrogen stage burning.

Charcoal is made by burning wood in the hydrogen stage (hence removing the hydrocarbons) but not allowing the carbon stage (by limiting the amount of oxygen).

3   Matter


The corner of a block of balsa wood viewed from an `electron microscope`_. Note how thin-walled the cells are.

There are 3 types of wood structures: ring porous, diffuse porous, and tracheids. 4 depending on who you ask (semi-ring or semi-diffuse which is somewhere between diffuse and ring porous.)

Tom Nunlist. Dec 12, 2012. Understanding Wood: Four Structure Types. https://www.popularwoodworking.com/techniques/understanding-wood-four-structure-types

All hardwoods have vessels (little pipelines) that are used in sap production. The size and distribution of these vessels vary among species; some are visible to the naked eye. When the vessels are cut across the end grain, they’re often referred to as pores, thus hardwoods are known as “porous woods” (see below for further classification). The size, number and distribution of the vessels affect the appearance and uniformity of hardness in a particular wood. Softwoods, which don’t have pores, are known as “non-porous woods.”

Ring Porous
In some species (e.g. oak and ash), the largest pores are in the earlywood while those in the latewood are more evenly distributed and uniform in size. These woods typically have distinct figures and patterns, and the uneven uptake of stain (the large pores soak up more color) make the figure more pronounced. These are also known as open-grain woods.
Semi-ring Porous
In some species (e.g. black walnut and butternut), pores are large in the earlywood and smaller toward the latewood, but without the distinct zoning seen in ring-porous woods. Also, some species that are usually ring-porous (e.g. cottonwood) occasionally tend toward semi-ring porous.
Diffuse Porous
In some species (e.g. maple, cherry and yellow poplar) the pores are distributed fairly evenly across the earlywood and latewood. Most domestic diffuse-porous woods have relatively small-diameter pores, but some tropical woods of this type (e.g. mahogany) have rather large pores. These woods usually have even uptake of stain (there seems to be no scientifically proven explanation of the cause of blotching). These are also known as closed-grain woods.
Softwoods don’t have vessel cells (water is conducted in the living tree in tracheid cells). Different softwoods have different growth-ring characteristics however. In white pine, the rings are non-distinct, and stain uptake is fairly even, as in diffuse porous woods. In yellow pine, where the rings are clearly visible, stain uptake in earlywood is more pronounced than in latewood, as in ring-porous woods.

3.1   Ash

Ash wood is used in `baseball bats`_.

Strong hardwood with good resistance to warping, scrapes, and dents. It is very durable but difficult to work with. It is usually used in furniture frames.

There are 16 species of ash which grow in the eastern United States. Of these, the white ash is the largest and most commercially important. [7]

Properties: Ash is a hard, heavy, ring porous hardwood. It has a prominent grain that resembles oak, and a white to light brown color. Ash can be differentiated from hickory (pecan) which it also resembles, by white dots in the darker summerwood which can be seen with the naked eye. Ash burls have a twisted, interwoven figure. [7]

Uses: Ash is widely used for structural frames and steam bent furniture pieces. It is often less expensive than comparable hardwoods. [7]

3.2   Beech

Strong hardwood with poor resistance to warping, shrinking, swelling, and dry rot. It is usually used in medium-quality furniture, particularly curved parts.

3.3   Birch


Birch wood.

Birch wood is fine-grained and pale in colour, often with an attractive satin-like sheen.

Ripple figuring may occur, increasing the value of the timber for veneer and furniture-making.

Due to the hardness of Birch, it is better to shape it with power tools, as it is quite difficult to work it with hand tools

Strong hardwood that stains evenly and has good resistance to shrinking, swelling, and warping. It is usually used in furniture frames and some Scandinavian style furniture. Birch is a cut below cherry, walnut, oak, mahogany, and teak because it cannot be worked with as easily. If you want delicate curved lines and carvings on your furniture, you will want to pay more for a better wood. However, if you want simple furniture with straight lines and no intricate carvings anyway, birch is a fine choice and can save you some money. Sometimes, birch is stained and sold as "imitation mahogany", "imitation cherry", or "imitation walnut". It is a decent substitute for mahogany or walnut in some simple styles of furniture, although it will not look quite as nice or last as long.

3.4   Cedar


Cedar wood.

Cedar wood is ....

Cedar wood is known to be a natural repellent to moths, hence cedar is a popular lining for modern-day cedar chests and closets in which woolens are stored. This specific use of cedar is mentioned in The Iliad (Book 24), referring to the cedar-roofed or lined storage chamber where Priam goes to fetch treasures to be used as ransom. Cedar is also commonly used to make `shoe trees`_ as it can absorb moisture and de-odorise.

Weak softwood. It is most often used for closet linings, decorative paneling, trellises, garden cedar chips, and shingles. Please note that only red cedar repels moths - other types of cedar do not.

3.5   Cherry

Strong hardwood that is easy to work with, wears well, stains evenly, and has good resistance to shrinking, swelling, and warping. It carves well, which makes it very well suited to furniture styles that have carved embellishments or curved lines. This is a very high-quality wood. It is also relatively expensive, but it is an excellent investment. If you want very high-quality elegant furniture, but don't want to go to the extra expense of purchasing mahogany, teak, or English walnut, cherry is a very good choice. It is available in a wide variety of furniture styles. If you love the look of cherry furniture, but you can't afford it, imitation cherry that is made of stained birch is a good substitute. It's only major drawback is that it is more difficult to work with and cannot be shaped or carved as well as cherry.

A moderately hard, strong, closed grain, light to red-brown wood, cherry resists warping and checking. It is easy to carve and polish. [7]

Cherry veneers and solids are used in a variety of styles. Cherry has been called New England mahogany and is often used to craft 18th century, Colonial and French Provincial designs. [7]

3.6   Ebony


Ebony wood.

Ebony is a dense black wood, most commonly yielded by several species in the genus Diospyros, but may also refer to other heavy, black (or dark colored) woods from unrelated species.

Ebony is dense enough to sink in water.

It is finely-textured and has a very smooth finish when polished, making it valuable as an ornamental wood. The word "ebony" derives from the Ancient Egyptian hbny, via the Ancient Greek ἔβενος (ébenos), by way of Latin and Middle English.

Strong hardwood that wears well and is easy to work with. It is extremely expensive due to its relative scarcity and the fact that it must be imported from a few tropical areas in Asia and Africa. It is normally used in decorative furniture inlays and small carved decorative accessories.

3.7   Mahogany



Mahogany is a commercially important lumber prized for its beauty, durability, and color.

Mahogany is used for paneling and to make furniture, boats, musical instruments and other items.

The leading importer of mahogany is the United States, followed by Britain;[1] while the largest exporter today is Peru, which surpassed Brazil after that country banned mahogany exports in 2001

Strong hardwood that is easy to work with, stains evenly, wears well, looks gorgeous, and is basically perfect. It's also basically expensive, but it's worth every penny. The main reason why mahogany is so much more expensive than cherry, oak, and walnut is that it must be imported from Central America, South America, or Africa. American mahogany is marginally higher-quality than African mahogany. Mahogany does have its own unique beauty, but it really does not wear any better than cherry, oak, and American walnut (which are grown in North America). So, if you want high-quality gorgeous furniture that will last a lifetime - cherry, oak, and American walnut are fine. The only reason to pay a higher price for mahogany is for its unique look. You might also consider purchasing imitation mahogany that has been made from birch, if you can't afford the real thing. Birch is a high-quality wood that will wear well for many years. It won't be quite as gorgeous or long-lasting as the real thing, but it makes a good substitute. Avoid imitation mahogany that has been made from lower-quality woods, such as gum or so-called "Philippine mahogany", which is actually a scam and not real mahogany at all.

Mahogany, also known as Honduras mahogany is a tropical hardwood indigenous to South America, Central America and Africa. There are many different grades and species sold under this name, which vary widely in quality and price. Mahogany which comes from the Caribbean is thought to be the hardest, strongest and best quality. Logs from Africa, though highly figured, are of slightly lesser quality. Philippine mahogany has a similar color, but is not really mahogany at all. It is a much less valuable wood, being less strong, not as durable or as beautiful when finished. [7]

Mahogany is strong, with a uniform pore structure and poorly defined annual rings. It has a reddish - brown color and may display stripe, ribbon, broken stripe, rope, ripple, mottle, fiddleback or blister figures. Crotch mahogany figures are widely used and greatly valued. Mahogany is an excellent carving wood and finishes well. [7]

3.8   Oak



Oak is a ...

Oak is the most widely used hardwood. There are more than 60 species of oak grown in the U.S., which can be separated into two basic varieties; white and red. The red variety is also known as black oak (a reference to its bark). [7]

Oak is a heavy, strong, light colored hardwood. It is ring porous, due to the fact that more and larger conductive vessels are laid down early in the summer, rather than later. Prominent rings and large pores give oak a course texture and prominent grain. Oak also has conspicuous medullary rays which can be seen as "flakes" in quarter sawed oak lumber. [7]

Oak wood has a density of about 0.75 g/cm3, great strength and hardness, and is very resistant to insect and fungal attack because of its high tannin content.

It also has very appealing grain markings, particularly when quartersawn.

Oak planking was common on high status Viking longships in the 9th and 10th centuries. The wood was hewn from green logs, by axe and wedge, to produce radial planks, similar to quarter-sawn timber. Wide, quarter-sawn boards of oak have been prized since the Middle Ages for use in interior panelling of prestigious buildings such as the debating chamber of the House of Commons in London and in the construction of fine furniture. Oak wood, from Quercus robur and Quercus petraea, was used in Europe for the construction of ships, especially naval men of war, until the 19th century, and was the principal timber used in the construction of European timber-framed buildings.

Today oak wood is still commonly used for furniture making and flooring, timber frame buildings, and for veneer production.

Barrels in which wines, sherry, and spirits such as brandy, Irish whiskey, Scotch whisky and Bourbon whiskey are aged are made from European and American oak. The use of oak in wine can add many different dimensions to wine based on the type and style of the oak. Oak barrels, which may be charred before use, contribute to the colour, taste, and aroma of the contents, imparting a desirable oaky vanillin flavour to these drinks. The great dilemma for wine producers is to choose between French and American oakwoods. French oaks (Quercus robur, Q. petraea) give the wine greater refinement and are chosen for the best wines since they increase the price compared to those aged in American oak wood. American oak contributes greater texture and resistance to ageing, but produces more powerful wine bouquets. Oak wood chips are used for smoking fish, meat, cheeses[13] and other foods.

Strong hardwood that is easy to work with, wears well, stains evenly, and has good resistance to swelling, shrinking, and warping. It carves well, which makes it very well suited to furniture styles that used carved embellishments or curved lines. This is a very high-quality wood. It is also a bit expensive, but it's well worth the money. If you want very high-quality furniture, but don't want to go to the extra expense of purchasing mahogany, teak, or English walnut, oak is a very good choice. It is available in all types and styles of furniture.

3.9   Teak



Teak is a yellowish brown timber with good grain and texture.

Teak, though easily worked, can cause severe blunting on edged tools because of the presence of silica in the wood.

Teak is often an effective material for the construction of both indoor and outdoor furniture. Teak's high oil content, high tensile strength and tight grain makes it particularly suitable for outdoor furniture applications.

Over time teak can mature to a silvery-grey finish.

It is used in the manufacture of outdoor furniture, boat decks, and other articles where weather resistance is desired. It is also used for cutting boards, indoor flooring, countertops and as a veneer for indoor furnishings.

Teak is used extensively in India to make doors and window frames, furniture, and columns and beams in old type houses.

It is very resistant to termite attacks.

Mature teak fetches a very good price.

It is grown extensively by forest departments of different states in forest areas.

Strong hardwood that is easy to work with, stains evenly, and has good resistance to wear, swelling, warping, and shrinking. It carves well, which makes it very well suited to furniture styles that used carved embellishments or curved lines. This is a very high-quality wood, available in all types and styles of furniture. Teak is quite expensive because it must be imported from Asia. Like mahogany and English walnut, the only reason to buy it is because it has a unique and beautiful look. Cherry, American walnut, and oak are just as durable and attractive and are less expensive because they are grown domestically.

True teak is indigenous to Southeast Asia, but similar wood species also grow in Africa. [7]

Properties & Uses: Teak is a yellow to dark brown hardwood which is extremely heavy, strong and durable. Often strongly figured, teak may show straight grain, mottled or fiddleback figures. It carves well, but because of its high value, is often used as a veneer. Scandinavian modern, and oriental furniture styles are often crafted of teak. [7]

3.10   Walnut



Video of the slab-cutting process showing an "Alaska Mill" used on a walnut trunk. In real time this was 7-8 minutes. This log was 10' long and 24" diameter. [9]_

The common walnut and the black walnut and its allies, are important for their attractive timber, which is hard, dense, tight-grained and polishes to a very smooth finish.

The colour ranges from creamy white in the sapwood to a dark chocolate colour in the heartwood. When kiln-dried, walnut wood tends toward a dull brown colour, but when air-dried can become a rich purplish-brown. Because of its colour, hardness and grain, it is a prized furniture and carving wood. Walnut burls (or 'burrs' in Europe) are commonly used to create bowls and other turned pieces. Veneer sliced from walnut burl is one of the most valuable and highly prized by cabinet makers and prestige car manufacturers. Walnut wood has been the timber of choice for gun makers for centuries, including the Gewehr 98 and Lee Enfield rifles of the First World War. It remains one the most popular choices for rifle and shotgun stocks, and is generally considered to be the premium – as well as the most traditional – wood for gun stocks, due to its resilience to compression along the grain. Walnut is also used in lutherie. The wood of the butternut and related Asian species is of much lower value, softer, coarser, less strong and heavy, and paler in colour.[3]

The American Black Walnut tree Juglans nigra does not grow as big as the Mahogany nor does it have the same growing seasons lengths. Comparing the two species is a little like comparing apples and oranges. Maple on the other hand makes a more apt comparison since it grows in the same geographic areas. Maple is a bigger, heartier tree, and can be aggressive thus starving other species like Walnut. Walnut is a light demanding tree and does not do well in windy areas. When surrounded by other more aggressive species the Walnut will not grow as tall, usually staying in the 30-70 foot range. [5]

The grading system for FAS Walnut has been downgraded to allow more wood into this top quality category. [5] So when our customers order FAS Maple or Oak and FAS Walnut we are quick to explain to them that when compared side by side, the Walnut may not be as clear and long as the Maple or Oak. This is not us trying to be sneaky but merely a factor of the downgrade in what is considered an FAS Walnut board. [5] However, in many cases these “defects” are exactly what the craftsman is looking for to put their own unique stamp in their creations. [5]

Strong hardwood that is easy to work with, wears well, stains evenly, and has good resistance to shrinking, swelling, and warping. It carves well, which makes it very well suited to furniture styles that used carved embellishments or curved lines. This is a very high-quality wood. It is also relatively expensive, but it is well worth the price. It is also known as "black walnut". If you want very high-quality elegant furniture, but don't want to go to the extra expense of purchasing mahogany, teak, or English walnut, American walnut is a good choice. It is available in all types and styles of furniture.

Walnut is strong, hard and durable, without being excessively heavy. It has excellent woodworking qualities, and takes finishes well. The wood is light to dark chocolate brown in color with a straight grain in the trunk. Wavy grain is present toward the roots, and walnut stumps are often dug out and used as a source of highly figured veneer. Large burls are common. Walnut solids and veneers show a wide range of figures, including strips, burls, mottles, crotches, curls and butts. European walnut is lighter in color and slightly finer in texture than American black walnut, but otherwise comparable. [7]

3.10.1   Market


  1. Walnut wood often has a curved curly grain that most people find more desirable in furniture then a straight grain.
  2. Walnut is so hard, strong and durable that furniture makers find it more desirable for their furniture. It can also be easily carved making it a great choice for ornate furniture that requires intricate woodworking.
  3. In pre-colonial days the walnut tree was plentiful, but specimans were used recklessly for solid walnut furniture and exported to Europe. The wood was also used for railroad ties, and fence rails because of it's durability when in contact with soil. This started the depletion of good walnut tree specimans.
  4. In the mid-1700's black walnut was used and favored for gunstocks in the Connecticut River valley so much that the high-quality black walnut tree population was wiped out by 1795. It is no longer found in New England. (Too bad they didn't have sustainable forestry practices back then.) Gun manufacturers had to start getting their hardwood walnut from as far away as the Ohio Valley, west of the Alleghenies. Making good specimans of walnut rather rare.
  5. The rare good specimans of walnut are so desirable that they are used as a veneer for furniture. The process brings out the best of the grain and allows for more to be used. Using the veneer also makes the furniture more affordable.

3.11   Wenge



Wenge is a tropical timber, very dark in color with a distinctive figure and a strong partridge wood pattern. The wood is heavy and hard, suitable for flooring and staircases.

4   Properties

4.1   Color

Woods range in color.

4.4   Waterproofness

Wood is basically water proof once it's soaked. A small amount of water will diffuse through, but for example wooden barrels can hold liquids for years without losing a large amount of their content. Wooden ships also don't take much water once they are properly soaked.

5   Classification

Every type of wood has a unique signature mark that can help in identification of the type.

There are hardwoods and softwoods. Both are used in furniture manufacturing, and each have their own specific uses.[1]

5.1   Solid wood

Solid wood is essential for post or legs that support furniture, for framing, or whenever carving is involved. Because of this, every piece of fine furniture is comprised of some solid wood. However, solid wood suffers from a number of issues. It bows and warps over time. Heat and humidity changes can make solid wood contract, leading to splits along the grain known as "season cracks". Solid wood is expensive and heavy. Solid wood does not bend easily.

Typically, the outer layer is made from the most beautiful or exotic woods, while the substrate is made from utilitarian woods or particle board.

Solid wood is highly durable can be repaired.

Solid wood will expand or contract according to humidity and may split along the grain of the wood. As a rule, wood should not be exposed to strong sunlight or direct heat sources.

5.2   Wood veneer

Wood veneer is a thin slice of wood cut or peeled from a log, usually thinner than 3mm, that typically are glued onto core panels to produce flat panels such as doors, tops, and panels for furniture.

The slice can be as thin as a piece of paper or thick enough to accommodate sanding and finishing down the road.

The veneer is adhered to another wood surface.

Veneers were discovered in King Tut's tomb and were used extensively during the Renaissance. By the 18th century, veneers had become an artform. When fine lumber was scarce during World War II, veneers because the only way to create furniture affordably, which is likely when they gained their reputation for poor quality.

Veneers offer several design advantages. Veneers are thin enough to bend and can be shaped by the cabinet maker. Many exotic wood are only available as veneers, or are excessively expensive when purchased as solid wood.

Many of the best wood is only available as veneer, since sellers and veneer makes can profit more from a high quality log sliced into veneer than they can from sawing it into boards.

Veneers also creates new design possibilities.

Veneer is stable since it is glued to a stable substrate; it is not prone to warp or split or seasonal movement.

5.3   Plywood


Plywood consists of three or more layers of veneer, each glued with its grain at right angles to adjacent layers for strength.

5.4   Particle board


Particle board is an engineered wood that is produced from wood chips, sawmill shaving, or sawdust, and a synthetic resin which is pressed and extruded.

Particle board is actually pressure-treated, glued-together, sawdust. Particle board furniture is a poor investment. It isn't very durable. It soaks up water (from the air) like a sponge and will eventually separate from the pretty veneers that often cover it.

5.5   Hardwood & Softwood

The classification of wood has historically always been either hard wood; any leaf bearing tree, and soft wood; any cone bearing tree. These terms can be confusing since some leaf bearing trees can have very soft wood and some coniferous trees can have very hard woods. [7]

Hardwood is ...

Hardwood includes wood which comes from `deciduous trees`_ such as cherry maple_, mahogany, oak, teak, walnut.

`Coniferous trees`_ such as ash, beech, birch, cedar, fir_, hickory_, pine_, redwood_, and spruce_ produce what is known as soft wood.

6   Usage

Generally speaking, quality furniture is made out of hardwood_. It is possible to find good quality furniture made of out softwood_, but since they are more prone to scratches and dents they require more care.

7   Degradation

Light makes wood change color over time in a process known as "mellowing". Some take on a warmer tone while other grow darker or lighten.

8   Maintenance

From Greycork on how to maintain the wood:

If liquid is spilled on solid wood, wipe it down immediately. Then, lightly dampen a towel with water, wipe the table top, then wipe it with a dry towel. Wipe with a mineral oil finish once per month to extend life of table.

From the family handyman on removing wood scratches:

Simply rub a walnut over a scratch in wood several times. Then, with your fingers rub the scratched area. This will help the wood absorb the oil from the nut. Lastly, use a soft cloth to buff the area. Now the scratch is sealed and gone!

8.1   Cleaning


How to apply mineral oil to wood. Sonder LA.

Directions for how to clean a wooden cutting board: [10]

We recommend that you hand wash your board in warm soapy water. Then rinse and pat dry immediately with a clean cloth. Stand the board up to allow the board to air dry evenly. Always wash both sides after use for even water absorption.

Hand wash only. Do not soak or submerge in water. Wood products should never be washed in the dishwasher.

Plainly speaking, soaking a wood cutting board will force it to become water logged and prevent it from fully drying out. This will cause deformations on the wood, known as warping, similar to how wood floors react to floods.

In addition to properly washing and drying your board, there is no better treatment than making sure your board is well oiled. Treating the wood with Food Grade `mineral oil`_ (or beeswax_) is imperative.

Avoid using cooking oils (olive oil, vegetable oil, canola oil, sesame oil, etc...) to treat your board. These types of oils are high in fat and once oxidized, can become rancid which can transfer an unpleasant smell into the wood.

Make sure your board is clean and completely dry before applying any oil.

Apply the mineral oil using a clean, dry dishtowel. Start with one teaspoon of the oil and evenly spread over the entire board using the dishtowel.

Leave the oil to absorb into the wood for several hours, or overnight if possible.

Remove excess oil using a dry, clean cloth, and wipe off any remaining oil so the board does not feel greasy.

Oiling is vital to protect the board from unwanted moisture such as bacteria, to prevent the wood from drying out which can lead to cracking, and to preserve the rich natural colors of the wood. We recommend oiling your board with a food grade mineral oil every 2-3 weeks or as soon as it appears dry. This will have a huge impact on the lifespan of your board.

8.2   Stains

There are two types of stains: white water stain and ???.

Ways to remove a white water stain: [11]

  • Use an iron on a towel. Keep the iron moving at all times or it will soften the finish, causing the rag to stick, and ruining the finish. This method works, but it's risky.
  • Behlen Blush Eraser and Mohawk No Blush both work. Let it sit for a little bit and then use a paint brush to spread it out so it dries more quickly.

Commonly recommended methods which do not work: [11]

  • Mayonnaise
  • Vinegar and olive oil
  • Toothpaste and baking powder
  • Salt and water

9   Market

The cost of lumber depends on the grade, length and width specifications (wider and longer boards are more expensive, non-standard (above the 6-8" range) boards are more expensive), seasonality, regional origin, import and export fees, shipping.

10   Grading

10.1   Lumber

For more than a century, the hardwood lumber industry has held to a central grading standard established by the National Hardwood Lumber Association (NHLA). Thanks to the foresight of the early founders of the NHLA in 1898, some order has been added to the chaos that had become the lumber trade. Keep in mind that NHLA grades apply only to North American Hardwoods.

At the turn of the last century when NHLA standards were set up, the furniture industry was still leading the pack in hardwood lumber consumption. So it follows that many of the specifications to meet the grade were based around the needs of the furniture maker.

There are two basic wood grades. Select lumber is excellent quality for use when appearance and finishing are important and common lumber that has defects used for construction and general-purpose projects. The grades of the select lumber are: B and Better grade, which has minute or no blemishes; C Select grade which has some minor defects such as small knots; D select grade that has larger imperfections, which can be concealed by paint. The grades of common lumber are No. 1 grade containing tight knots and few blemishes. No. 2 grade that has more and larger knots and blemishes. No. 3 grade that has loose knots, knotholes, and other flaws. No. 4 grade that is low quality and No. 5 grade where the appearance is not important. [7]

I think most of us are aware that a completely defect free board with no sapwood is going to be more expensive than a board full of knots and worm holes.

The following is considered unacceptable by NHLA standards:

  • Knots
  • Checks, splits, and bark products
  • Pith and wane
  • Worm or grub holes
  • Bird pecks
  • Rot or decay

A knot.

The following elements are acceptable and will not affect the cutting sizes:

  • Sapwood
  • Mineral streaks
  • Burl
  • Sticker marks
  • Gum streaks

These elements do not effect the structural integrity of the lumber and in many cases can be seen as appealing character depending on the industry and final use.

10.1.1   Characteristics


The following page shows characteristics that occur in US hardwoods. Some are specific to certain species and others are generic to all. These characteristics either occur naturally in the lumber or as a result of the drying process. The grades are based on the percentage of clear, defect free wood in the board.

Note: Although the NHLA grading rules do not consider these characteristics as defects for the standard grades, allowances are made within the individual species. For example, species such as hard maple and ash are more desirable if there is a large portion of the board that is sapwood (white) and very little hardwood. The reverse is true when specifying species such as cherry, oak and walnut. It is essential that the buyers familiarise themselves not only with each species but the growing regions throughout the USA as well. Climate, soil and growing conditions such as hills and valleys all play an important role in the growth of the tree. As previously stated, the NHLA rules are the framework to begin the trading process.

The NHLA grading rules allow the following characteristics in the clear cutting percentages for all grades and they are therefore not considered defects.

Heartwood is the mature wood, which is often darker, extending from the sapwood to the pith. Sapwood is the lighter coloured wood growing from inside the bark to the heartwood


A burl is a swirl or twist in the grain of the wood that does not contain a knot.


Gum streaks are mineral-like streaks of color naturally occurring only in cherry.


Minerals streaks are streaks of color ranging from olive to blackish-brown, which typically follow the grain pattern.


Glassworm is Random mineral like tracts. Usually associated with ash.


A sticker mark is The mark left on the board from a seasoning sticker, which can be removed in the surfacing planning process

NHLA grading rules do not allow the following characteristics in the clear cuttings for all grades and they are therefore considered defects.


A bark pocket is A bark-filled distortion in the grain pattern


Bird pecks are Small blemishes in the grain pattern resulting from bird pecking that sometimes contain ingrown bark. An exception to the rule is hickory and elm


A check is A lengthwise opening on the face of the board resulting from rapid or faulty drying


Decay or rot is The breaking down of the wood substance by fungi. The discoloration of the sapwood indicates the initial evidence of decay.


An unsound knot is A circular area that once formed the base of a branch or twig and has a pith centre. (In some cases the wood may be missing).


A sound knot is A knot solid across its face, which shows no indication of decay.


A split is A lengthwise separation of the wood created as the wood dries. Shake is a separation between the annual growth rings.


A sticker stain is a stain that is typically grey in colour occurring from stickers used to season lumber.


Wane is Bark or lack of wood caused by the round nature of the tree or log.


Pith is The small soft core at the structural centre of the tree.


Worm holes are Holes in the wood ranging in size from 1/16” to over ¼”


Grub holes are Holes larger than 1/4”

10.1.3   FAS 1 Face and Select

This grade developed later where one face may be of FAS quality but the other of at least a No 1 Common grade. Select requires the same stipulations but now the minimum board size reduces to 4″ x 6.

11   Further reading


12   References

[1]http://en.wikipedia.org/wiki/Furniture#Types_of_wood_to_make_furnitureg (Furniture)
[2]http://en.wikipedia.org/wiki/List_of_woodsg (List of woods)
[3]http://en.wikipedia.org/wiki/Juglans#Woodg (Walnut)
[4]http://en.wikipedia.org/wiki/Millettia_laurentiig (Wenge)
[5](1, 2, 3, 4) http://www.mcilvain.com/fas-downgrading-for-walnut-lumber/
[6]Shannon Rogers. Dec 13, 2013. How Much Will My Lumber Cost? http://www.mcilvain.com/how-much-will-my-lumber-cost/
[7](1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14) Types of Woods. http://www.hoovedesigns.com/woods.html
[8]Rebecca. October 10, 2009. Why is Walnut Furniture More Expensive? http://getinthemilkcrate.blogspot.com/2009/10/why-is-walnut-furniture-more-expensive.html
[10]Sonder LA. How to care for your wood cutting board. https://sonderla.com/pages/care
[11](1, 2) WeRefinish. 2019-05-25. Removing white water rings and heat stains from wood furniture | THE ULTIMATE GUIDE | NEW VERSION. https://www.youtube.com/watch?v=GZK1jjHsurs