This guide is meant to help you get the most out of the database. Here, I’ll try my best to explain what each of the features mean that are included in each wood profile, and why they are important.
Let’s start off with something that’s not even a “term” at all, it’s the main profile picture:
Profile Picture:
In the top left of (nearly) every wood profile, you’ll see a 200 x 200 square showing a good representation of the wood species. You can also click this square and see an enlarged 600 x 600 image as well. In most cases, this is actually a digital scan of the wood, and is meant to be as accurate as possible in regards to color and detail.
Note that this picture shows the wood in its unfinished, unstained, and otherwise “raw” state. All that has been done beyond surface planing is a quick sanding: usually to 120-grit or thereabouts. Very often, wood will get darker when a finish is applied, and so in addition to this raw picture, I’ve also tried to include another scan at the bottom of the page that shows the same section of wood with either a shellac sanding sealer or mineral spirits applied: this will give a more accurate representation of the color of the wood in a finished project.
Common Name:
This is the name that everybody uses when talking about the wood. It can sometimes be vague, because there are some instances where two different species of wood are called by the same common name. (One example would be Philippine Mahogany.) Yet, I’ve tried to list the most commonly used name(s), and have omitted most questionable alternative names unless I’ve specifically heard/seen that name used from multiple reliable sources.
Take for example Cocobolo: one reference I checked listed an alternate name as “palo negro.” Huh? I’ve never heard anyone call it by that name, so I’ll spare the obscure names from cluttering the entry.
Scientific Name:
This is a much more precise way of referencing wood: the only downside is that it’s Latin, and doesn’t make much sense to most English-speaking people.
The name is listed in two parts: [Genus species]; so in the example of White Oak, it would be listed as [Quercus alba], where Quercus is the genus of the tree, and alba is the species. When two or more species are included in a genus under a single common name, only the genus will be listed, with a “spp.” afterward. For example, Purpleheart is comprised of many similar species, and is listed as: Peltogyne spp.
If you click on the link to browse the database by scientific name, you will see different woods organized by genus: so all of the Oaks would be listed under the Quercus genus.
Distribution:
This is the location(s) where the tree is commonly found; that is, where it naturally grows. This can be helpful to determine if a wood is imported, or if it’s domestic. A tree’s distribution can also be a good conversation piece for a project if the wood used comes from a foreign or distant land.
Also, additional source data will be included on a wood species if it is commonly grown on a plantation or is harvested from some other non-native area, such as Teak.
Tree Size:
Beyond just giving a good visualization of how large the tree of a given wood species grows, (in height and diameter), these measurements can also help to give an idea of what size boards/lumber is available.
For instance, Swietenia macrophylla (Mahogany) trees grow very large, and it wouldn’t be surprising to see very wide (16″ or more) boards for sale. Yet it would be nearly impossible to find a board that large from a much smaller tree, such as Dalbergia cearensis (Kingwood).
Average Dried Weight:
This is a measure of a wood’s weight in relation to a preset volume. Usually it’s pounds per cubic foot (lbs/ft3), or in metric units: kilograms per cubic meter (kg/m3). However, a wood’s weight will also greatly depend on it’s moisture content (MC). For instance, a board that has just been freshly cut (called “green” wood) can weight more than double its oven-dry weight! Since there are so many sources of information on wood properties, and not all of them use the same standards and testing procedures, there can be a great variety in weight readings.
I’ve made every effort to standardize all readings to reflect the weight at a 12% moisture content; this is the most common standard of measurement for nearly all wood testing conducted worldwide. A moisture content of 12% is attained when a wood sample has reached equilibrium moisture content (EMC) with the surrounding air at a temperature of 70°F and a relative humidity of 65%. Storing wood in areas where the relative humidity is lower than this will result in a lower moisture content, and therefore a correspondingly lower density.
Take time to compare a density reading to another well-known wood, and see how it measures up. For instance Red Oak is about 45 pounds per cubic foot, (or 730 kilograms per cubic meter), which in and of itself isn’t too terribly useful, seeing as how you will most likely never encounter (or be required to lift) a piece of oak that is a perfect one-foot (or one-meter) cube. However, if you make a mental note of this weight, and use it to gauge other woods, you can quickly get an idea of how much things weigh. (For example, you can quickly see that Western Red Cedar weighs about half as much as Red Oak, but Lignum Vitae’s weight is almost double that of Red Oak!)
Additionally, in general terms, a wood’s density can be used to deduce a number of things about a wood’s properties; i.e., hardness, strength, etc. The heavier a wood is, the harder and stronger it is, in general.
Basic Specific Gravity:
Technically, specific gravity is a measure of density, so it might seem a bit redundant to list this field right after the dried weight density reading. But because of the diverging measurements found in the dried weight values of wood samples at widely varying moisture levels, (see listing above), specific gravity is intended to provide a standardized base measurement for the density of wood.
But when measuring a wood’s specific gravity, that is, its ratio of weight as compared to water, typically it is based upon a wood’s oven-dry weight, (meaning a moisture content of 0%, which is the lightest the wood can ever get), and its green volume, that is, when it is freshly cut: having the largest possible volume. This may seem like a double-standard—to calculate this density from the wood’s dry weight, and its green volume—but this standardization, commonly called the “basic specific gravity,” prevents any irregularities or inconsistencies from occurring, mainly because it uses predictable extremes (i.e., lightest weight and largest volume) to calculate the SG value.
Using a wood’s basic specific gravity, along with its volumetric shrinkage data, the average dried weight can be calculated at a number of moisture contents, ranging from 0% up to 30%.
Hardness:
Commonly called the Janka hardness test, this number is incredibly useful in directly determining how well a wood will withstand dents, dings, and wear—as well as indirectly predicting the difficulty in nailing, screwing, sanding, or sawing a given wood species.
The actual number listed in the wood profile is the amount of pounds-force (lbf) or newtons (N) required to imbed a .444″ (11.28 mm) diameter steel ball into the wood to half the ball’s diameter. This number is given for wood that has been dried to a 12% moisture content, unless otherwise noted.
For reference, White Oak has a Janka hardness of 1,360 lbf (6,000 N), while the super-hard Lignum Vitae has a hardness of an astounding 4,500 lbf (20,000 N). (Who could imagine a wood species that is over three times harder than White Oak?) On the lower end of the spectrum, Basswood has a hardness of around 410 lbf (1,800 N).
Also, in some instances, I’ve estimated the Janka hardness value using equations that use the wood’s basic specific gravity, as found in the paper, “Estimating Janka Hardness from Specific Gravity for Tropical and Temperate Species.”
Bending Strength:
Also known as modulus of rupture (MOR), this is a measure of a specimen’s strength before rupture. It can be used to determine a wood species’ overall strength; unlike the modulus of elasticity (seen below) which measures the wood’s deflection, but not its ultimate strength. (That is to say, some species of wood will bow under stress, but not easily break.)
MOR is expressed in pounds-force per square inch (lbf/in2) or kilopaschals (kPa). This number is given for wood that has been dried to a 12% moisture content, unless otherwise noted.
In practical terms, the number itself isn’t all that meaningful, but it becomes useful to use in comparison with other woods. For instance, Hickory is known to have excellent strength properties among domestic species in the US, and has a MOR of 20,200 lbf/in2 (139,310 kPa). In comparison, Red Oak is another well-known wood used cabinetry and furniture, and has a MOR of 14,300 lbf/in2 (98,620 kPa).
Elasticity:
In the most simple terms, the modulus of elasticity (MOE) measures a wood’s stiffness, and is a good overall indicator of its strength. Technically it’s a measurement of the ratio of stress placed upon the wood compared to the strain (deformation) that the wood exhibits along its length. MOE is expressed in pounds-force per square inch (lbf/in2) or megapaschals (MPa). This number is given for wood that has been dried to a 12% moisture content, unless otherwise noted.
In practical terms, the number itself isn’t all that meaningful, but it becomes useful to use in comparison with other woods. For instance, Hickory is known to have excellent strength properties among domestic species in the US, and has a MOE of 2,160,000 lbf/in2 (14,900 MPa). In comparison, Red Oak is another well-known wood used in cabinetry and furniture, and has a MOE of 1,820,000 lbf/in2 (12,500 MPa).
Shrinkage: Radial, Tangential, and Volumetric
These values measure the change in wood when going from a freshly cut (green) state, to an oven-dry (0% moisture content) state.
Radial shrinkage is the amount the wood has shrunk across the grain.
Tangential shrinkage is a measurement of the amount the wood has shrunk along the grain. (Not to be confused with longitudinal shrinkage, which measures the shrinkage along the entire length of the board, which is usually very slight,:under .5%)
Volumetric shrinkage is an overall measurement of how much the wood has shrunk in volume during the drying process.
T/R Ratio is the ratio of tangential to radial shrinkage. The smaller the ratio, the more likely a wood is to stay flat and avoid warping due to seasonal expansion and contraction.
In a nutshell, the shrinkage numbers tell the magnitude of the wood’s movement with changes in humidity, and the T/R ratio shows the stability of the changes.
(More information on shrinkage can be found in the article about quartersawn woods.)
These numbers are very valuable in determining how stable the wood will be in service with respect to changes in relative humidity. In and of themselves, the numbers can be hard to decipher, but with a few simple reference points, they can quickly provide useful information.
For instance, Honduran Mahogany has long been considered to have excellent shrinkage properties—setting a standard for stability. While other woods have a much higher level of movement, such as American Beech.
Color/Appearance:
A general description of the physical appearance of the wood. For most woods, the color will be of the heartwood, as that is the area of the tree that is most commonly used for lumber, with a few exceptions.
Grain/Pore:
This describes any visual/physical characteristics that pertain to the grain pattern and pores of the wood. It could range anywhere from the giant, valley-like pores found in Wenge, or the smooth, closed-pored grain of Hard Maple.
Durability:
This refers to a wood’s ability to resist elemental and natural forces of decay: whether that be from rain/moisture, or from termites or other boring/destructive insects. (This assessment is only based on the tree’s heartwood, and not its sapwood—as only the heartwood has any appreciable degree of durability anyhow.)
An overall chart defining the terms used to describe a wood’s durability in direct ground contact:
Classification Service Life
(in years)
Very Durable 25+ Durable 15-25 Moderately Durable 10-15 Non-Durable 5-10 Perishable less than 5
For instance, the lumber from Mango trees is frequently subject to spalting and decay, and insects feast on the wood so readily that it has been called “Bug Candy.” On the other end of the spectrum is wood such as Teak, which is well-known for its durability, and is frequently used in boat-building and other outdoor applications.
Workability:
A brief overview of any possible difficulties that may occur when machining, gluing, and finishing the wood.
Smell:
Sometimes when you can’t quite tell what wood species you’ve got visually, and you’ve got it narrowed down to only a few, one of the best ways to identify it is to saw/sand into it and take a sniff. Grain and color can be highly variable among wood species, but usually its scent is very distinct. I’ve tried my very best to describe the smell of the wood in words: a task that can be difficult to do accurately.
Safety:
Lists any known allergies or toxicity information for the wood. For more information, see the articles on Wood Allergies and Toxicity, and Wood Dust Safety.
Price Range:
Exact prices change all the time: I’ve tried to avoid giving precise dollar amounts on any given wood species, but have instead tried to give a description of a wood’s overall scarcity, sustainability, and price in comparison to other wood species.
Comments:
This is an open-ended section where any notable aspects of the wood species can be mentioned.
Related Species:
A wood species must be in the same genus in order to be considered related in this field. Hence, some woods that seem to be related, such as African Mahogany and Honduran Mahogany, will not be listed because they belong to different genera (Khaya and Swietenia, respectively). Likewise, other woods that seem completely unrelated, such as Narra and Padauk, will show up as related species since they are both from the same genus (Pterocarpus).
Scans/Pictures:
In this section I’ve tried to give a good representation of what the wood can/will look like in a woodworking project. Most wood species will have at least one additional scan of the wood once it’s been sealed with a sanding sealer in order to give a more accurate representation of the wood’s finished color. Also, if the wood species has any other figured forms, (such as curl, spalt, quilt, etc.), I’ll try to include a scan of the variant(s) as well.
I may also include photos of finished wood projects with a top-coat applied, or images of what the wood looks like once it’s been turned on the lathe and in a cylindrical form, or even videos or other multimedia to help demonstrate the wood’s properties. (For instance, the profile for Honduran Mahogany features a video showing the chatoyance of the wood.)
