Wood Selection: Choosing the Right Kind

Hardwood vs softwood: What is this all about and what's the difference? “Softwoods” aren’t all that soft, and “hardwoods” aren’t all that hard. The four softest woods are hardwoods, in fact, the top 10 softest woods are a dead split between hardwood and softwood. However, in general hardwoods are harder and the hardest woods are hardwoods.

Let me lay a little science on you: Softwoods are Gymnosperms, or Acrogymnospermae. In actual words this means a softwood reproduces via naked seeds: a pine cone for instance ruptures and spreads its seeds.

Hardwoods are Angiosperms: or seeds which are cased in some sort of vessel. Think of a nut or a fruit tree: the nut or fruit is always cased in something (an apple, a walnut shell, etc). Not all hardwoods have edible fruits or nuts.

Commonly you will hear people refer to hardwoods as deciduous, however Holly, Magnolia and a number of other trees are hardwood and are not deciduous.

Which one do I need? It is project dependent, but usually general home repair and carpentry use softwoods (pine and cedar) and furniture or fine woodwork require hardwoods. Why would I choose one over the other?

Usually the biggest factor is cost and availability: Softwoods are almost always cheaper and more readily available. Hardwoods are usually more durable, prettier and nicer to work with, often this isn’t necessary and the cost doesn’t make sense. Some projects need the strength or elasticity of a specific wood, and it isn't always best to go cheap

Rift sawn, quartersawn, plain sawn, live sawn, flat sawn are a handful of terms for the processes used to create lumber. Quartersawn and rift sawn are the same thing by another name and section of the board (see image) quarter sawn boards are the most dimensionally stable cuts. They often show off rays and flecking in certain species (White Oak).

Quartersawn is the most premium because it creates the most waste. Rift sawn is similar to edge cuts of a live board and can be an excellent source of straight grain lumber. Plain sawn is common with large diameter trees as boards over a certain width are unstable. Live or flat sawn are common in smaller trees or ones that will be sold as live edge

Wood is measured in Board footage: Rough cut lumbers are measured this way, and this is the measurement used if you visit a store that specializes in hardwood. One board foot is 144”3, or a 12”x12”x1” section. This is done because there are varying thicknesses, lengths and widths, remember this is a natural and minimally processed product.

Wood sold in board footage is always thickness measured in “quarters” which is lingo for a quarter of an inch. So a “four quarter” board is 4/4” or one inch, this could be any number, 1/4, 5/4. 10/4. To convolute that a little more that is the raw cut thickness. A 4/4 board will usually end up being closer to 7/8” thick.

Linear footage: Dimensional lumber (2x4’s for instance) will be sold in linear footage, meaning priced by the foot. Dimensional lumber is also not true to the noted dimension, if you measure a 2x4 you will find it is close to 1.5”x3.5”, that is because it is rough cut to 2”x4” dried, then finish milled to final dimension.

This is industry standard: you're not going to avoid it, just plan for it instead. Dimensional measurement is the common type of measurement at “big box” stores. If you buy hardwood at a place like this it will be priced by linear foot. Avoid buying hardwood at big box stores, it is usually twice or more the cost of buying from a hardwood supplier!

Where to buy: Hardwoods should be sourced from a dedicated vendor, examples in Denver are Austin Hardwoods, Paxtons Lumber, or CS woods. A second choice would be Rockler or Woodcraft (Sometimes their prices are higher, but if they are having a sale they can be lower). Avoid stores like Lowe’s or Home Depot for hardwood, prices are unreasonable.

Softwoods are widely available, if you are buying a large quantity a dedicated lumber yard is your best bet on quality and price. If you only need a few, or few dozen boards the big box stores are OK for this.

Online retailers are becoming better and more viable options. Just watch shipping, especially on long lengths or particularly large sections.

A note on pricing: You will find most dedicated hardwood stores don’t post prices online or in their warehouses. Wood is a market good, the prices are constantly shifting, the price of the woods will reflect this. You can call any hardwood place and ask for the days pricing.

MDF: “medium density fiberboard” is a composite wood that is essentially wood dust and glue compressed together. Its strengths are: inexpensive, good impact resistance, available in a variety of coatings and colors, reasonably strong, uniform strength, homogenous processing and machining properties.

Weaknesses: Poor shear strength, very susceptible to water damage, heavy, extremely dusty unless you purchase a domestic product it probably contains formaldehyde, this means any MDF sourced from a big box store! Always wear a respirator when cutting or sanding MDF. You can also buy HDF or LDF (high or low density).

Plywood: There are a variety of types, thicknesses and constructions. It can be made out of or veneered in any wood species, it can be marine grade, low grade, finish sanded or not. There is too much to cover in this guide, consult google or a shop worker for help in choosing what you need.

In general it has excellent strength and working characteristics, prices vary drastically based on application and construction.

Masonite: a composite hardboard made of steam cooked, glued and pressure molded wood fiber. It's often used for its smoothness in things like table tennis boards or final layers skateboard ramps. It has good impact resistance, is somewhat flexible, but will tear apart once it has exceeded its flexibility. It has very little water resistance.

Waferboard or OSB: Is a composite wood product manufactured from rectangular wood flakes with a minimum and maximum size limit, bonded together with a phenolic resin. It is often used as casement for exteriors but has minimal water resistance and must be covered or coated.

Manufactured “lumber”: “Lumber” generally refers to boards rather than sheet goods, Trex and other composites fall into this category, they are a molded product similar to one of the above designed to mimic real wood, they have their own strengths and weaknesses, there is a great deal to cover with these so it won’t be covered in this guide.

Other sheet goods: The selection of sheet goods is vast, too much to cover here, but if you are looking at something not listed here you should understand its properties before purchase.

Straightness: Every board you buy should be checked for straightness and twist. Whether it’s a 2x4 or an exotic hardwood it does not matter. Straight boards will be easier to work, tool and process. Please take the time to find yourself some quality wood. Twist, cupping, and bowing in wood is never desirable.

It's difficult to plane straight, impossible to cut on a table saw and you often end up losing a great deal of wood getting a piece flat, worse than this: once you relieve the stresses the defect can actually reappear in days or weeks.

Curved boards should only be purchased for very specific circumstances where a curved grain structure is desired. If this is the case you should take patterns with you for the curved section you need so you can ensure you are getting the match required.

Grain orientation and patterning: All boards, and sections of boards have specific strengths and weaknesses.

Long grain vs Cathedrals: These phenomenon occur based off of where the wood is cut from the tree. Long grained sections will come from portions of the wood cut near the edge of the tree and cathedral sections will come from the center cut of the wood.

Straight grain sections are excellent for legs: they look uniform from all sides of the cut and are extremely strong and flexible in the planes of the grain.

Cathedral sections are best for tops and aprons: They are visually interesting, beautiful and more than strong enough for these applications as they will rarely see high impact and shear loads.

Sight down the board: to check for straightness, twist and warp. A Board: On the left side of the dashed line you see straight grain, from the edge of the tree. On the right you can see the cathedrals from a center cut of the tree

Heartwood vs Sapwood: Every tree has both of these. It is important to read up on the species to determine if it matters for your application or not.

For instance: most rot and weather resistant woods are only resistant in the heartwood. This is especially true in cedar and redwood, the heartwood of these species is extremely rot and insect resistant, but the sapwood is not and will literally rot away from the heartwood in outdoor uses. White Oak and Teak’s sap woods aren't weather resistant!

Other aesthetics: Take a moment to understand why the wood you are buying looks the way it does. In the case of wormy or ambrosia maple the long dark streaks in the wood are actually caused by tiny worm holes, the discoloration is due to the tree fighting back. Are the little holes going to be a problem in your design?

Knots and burls can be really nice touches in a piece, but watch for cracking, check to make sure the knots aren't loose, if they are you will have to stabilize them before you process the wood or you will be left with a void.

Curly pieces of wood are beautiful, but unless you have high quality planing tools you will almost certainly be left with tear out and a lot of sanding. Large sections of burl are visually stunning, burl is more uni-directionally stable than other woods but it is extremely difficult to machine without tearout and the price tends to be prohibitive.

A single walnut board: Was cut up to build a table. On the left: the center of the boards was taken and resawn to use as the top. Bottom middle: more center board section will be laminated to form aprons.

Right: the outer sections will be used for their straight grain to turn legs. Because this table is made from one board it will have uniform color and patterning.

Hardwood or softwood? This is probably most easily answered by determining what sort of construction is to be used. If the object is to be assembled via fasteners: screwed, doweled, domino’d or nailed together, softwoods or sheet goods are adequate. If you are using joinery and glue a hardwood is a better choice.

Assembly type can be determined by how long you expect the item to last: 1-5 years of use can be accomplished with fasteners. If you want an item to last 5+ years, your lifetime, and probably many lifetimes beyond that joinery and glue is required.

Aesthetics: Sometimes a species is chosen for no other reason than look or feel. Please remember there is a lot more to building quality items than looks. Instead first select a few species that will do what is required then select the look you like most; remember most woods change color as they age, will that benefit the piece or take away?

Another item to be noted: in general practice hardwoods are not dyed or stained, choose a wood you like the aesthetic of to begin with, that way if it gets scratched or dented there is minimal impact to the surface uniformity. Dying, staining and finishing are their own separate processes from woodworking.

Costs: Wood can vary from a few dollars a board foot to over a hundred. Build full scale drawings and a cut list, compare the total wood price to your budget. Don’t forget to add 20% to your material bill to account for waste and processing losses. Would one species keep your budget and another blow it?

Combining woods: It is fairly common to have a design which utilizes at least 2 species. Normally it isn’t a problem, if you verify your design and pay attention to the species. Potential issues exist due to different shrinkage rates: If you are looking at 2 species with different shrink rates combining them could cause engineering trouble.

Other potential issues come when sanding: woods like redheart are also used as dyes, when you are sanding bloodwood mixed with another wood (especially a light colored wood) you will get color transfer from the bloodwood to the other. It's hard to avoid at the sanding step, but if you are aware, you can simply use redheart instead of bloodwood.

Finishing pieces with multiple species: If you are using a very hard wood and a very soft wood the hard wood will hold up to sanding a lot better, it will create high spots. Try to use woods that are of a similar hardness if your design shows this might be a problem.

Specifications for a species can be found via books or the internet. The easiest to use is wood-database.com. Janka Hardness: this is dent resistance. It is determined by pushing an 0.444” steel ball 0.222” into the piece, the number is force required. This is something important in hardwood flooring, but does it matter for a lamp?

Weight: Usually in pounds per cubic foot. Modulus of rupture: This reflects bending strength, it is the best determination of overall wood strength Elastic modulus: this is the woods ability to deflect. Rot resistance: Important if the item will be used outdoors or in a kitchen/bath

Crushing Strength: AKA compression strength. This is how strong the wood is in the direction of the grain. This will determine how much weight something like a table leg can support at a given size. Shrinkage: swell, this is usually a percentage and tell you how much the wood will change in size across the grain with moisture.

Grain/texture: straight grain woods is the easiest to work, interlocked grain will be the toughest and most difficult to machine. Workability: Description of how much the wood will fight you and good way to look at how hard the wood will be on tools. Allergies/toxicity: This is a good way to figure out how careful you need to be.

Effects of aging: Some woods like cherry age beautifully, it turns from a soft pink to a deep reddish brown. Other woods such as purpleheart age poorly: it turns a very undesirable brown color and loses most of its purple hue. Purpleheart is also very hard on tools, it’s use should be avoided. WOOD COLOR CHANGE WITH TIME CANNOT BE PREVENTED.

Oak is oak, right? Not at all. There are 600+ species of oak, and each specific species has different characteristics: White oak is rot resistant while red oak is perishable, pin oak is about 20% harder than any other oak species, and they are all visually different! Just saying something is made of “oak” or “Mahogany” doesnt tell the whole story.