When a client is choosing the wood for their cabinetry one of the questions I am often asked is “How hard is the wood?” What they want to know is how well it will hold up under daily use. I’ll try to keep it simple and hopefully the following proves helpful.
Hardwood Versus Softwood
First, clients often say they want hardwood cabinets, not softwood. Unfortunately this can be misleading. The terms “hardwood” and “softwood” have nothing to do with the hardness or softness of the wood. Hardwood, by definition, simply means a deciduous tree, that is, a tree that sheds its leaves every year whereas Softwood is a coniferous or evergreen tree – one that does not shed its leaves. Based on this balsa wood is a hardwood although it is one of the softest woods available. Cork is also a hardwood. White pine, hemlock and Douglas Fir are all softwoods and are softer than most hardwoods but yellow pine is harder than silver maple (also called soft maple). An old lumberjack I knew years ago said that he thought the two terms had to do with the hardness of the bark but I’ve never been able to verify this.
There is a hardness scale called the Janka Hardwood Scale which tests the impact resistance of woods and is used primarily by flooring companies to demonstrate the durability of their flooring. They run the test by forcing a metal ball into the surface of a board with a machine to see how much force it takes to penetrate halfway into a board.
To give you a sense of the scale: Brazilian walnut is one of the hardest available and has a Janka score of 3684. Red oak, which is the most common cabinet wood, has a Janka rating of 1290. At the low end of common cabinet woods, Eastern white pine is rated at 380 (for comparison, balsa wood is 100).
While the Janka scale is useful in flooring it is not as useful for cabinets. This is because flooring is subject to tremendous stress from people walking on it. Flooring must take a lot of abuse due to the weight and velocity of people walking on it. My dad used to work in an office in New York City in the 1960’s and at that time spike heels became very popular for the women working there. They had oak hardwood floors and soon discovered that spike heels do a lot of damage to wood floors. A 125 pound woman wearing ¼” spike heels exerts 2000 pounds per square inch of force and that is just standing there. Add velocity and the force exerted can reach 5000 pounds of force! As a result the company stopped allowing the employees to wear spike heels.
But we don’t walk on cabinets and they are seldom subject to impact with hard objects (unless you have children who like to throw things). (As an aside, here at The Cabinet Guy LLC we repair busted cabinet doors and after the Broncos lost to the Ravens in the AFC Championship game this year we had several clients bring us doors that had been kicked in from frustrated fans).
The most common wearing of cabinet doors and drawer fronts that I see comes from fingernails and knives, silverware and utensils. The scars from fingernails are usually around the door handle or, if you don’t have door handles, at the place where you grab the door to open it. The damage from metal utensils is usually along the top of the drawer fronts where you keep these items. No matter how hard the wood, eventually all this scraping will wear off the finish and scar the wood. The only sure way to avoid it is to be careful (especially if you have long fingernails).
Practical Advice Regarding Wood Durability for Cabinets
Rather than get into the Janka hardness scale I simplify this by grouping the most common cabinet woods into three categories: Very hard, medium hard and soft as it applies to the fingernail and metal utensil test.
Very Hard: Birch, hickory, pecan, hard (sugar) maple (the species used for butcher blocks), white and red oak, ash, lyptus and beech
Medium Hard: Yellow (Southern) pine, carbonized bamboo, American walnut, American cherry, soft (silver) maple, wormy maple and African (ribbon-grain) mahogany
Soft: Cypress, alder, hemlock, white pine, basswood and poplar (commonly used for paint-grade cabinets but medium density fiberboard - MDF - is a much better choice since it is much harder, about 1200 on the Janka scale -similar to oak - versus 540 for poplar)
I have had people tell me they want knotty alder instead of pine because pine is too soft. The truth is that while alder has a Janka rating of 590 and Eastern white pine is 380, practically speaking, there is not much difference in the durability of the two woods. (If you want the look of alder but much harder consider knotty beech which has a Janka rating of 1300 versus 590 for alder.)
The above scale applies to solid wood parts. When a veneered panel is used its durability is determined by the density of the core material. The densest core material commonly used is medium density fiberboard (MDF) which has a rating of 50 pounds per square inch (PSI) meaning it takes 50 pounds of pressure to dent it, the equivalent of a strong person swinging a hammer hard from two feet away. In comparison, cabinet-grade particle board is around 37 PSI and standard plywoods are around 25 PSI. Thus, MDF core veneer panels will hold up better than plywoods.
Effect of the Varnish on Wood Durability
Another factor that affects the wear on the cabinets is the thickness and hardness of the finish coats. The heavier and denser the coats the more durable they are. At The Cabinet Guy we use a water-borne Greenguard certified finish called Aqualente made by ML Campbell and build a 5-6 mil layer of varnish through successive coats (a mil is 1/1000 of an inch – a strand of hair is 2 mils). In the world of varnish 5-6 mils is considered a heavy coat sufficient to stand up to years of wear and tear. Aqualente has a very high solids content (42%), almost double a standard industry lacquer (25%), which makes it very durable. (Click here to see the performance and chemical resistance characteristics of Aqualente).
Many factories apply less than 5-6 mils, the average is 3 mils. Also, many boast that they oven cure the finish (we don’t) but don’t be fooled by this. It does not make the finish any harder, it only speeds up the drying so they can ship the cabinets sooner and bill the buyer faster.
The Bottom Line
While the hardness of the wood is a factor in your cabinet choice I recommend to my clients that they focus more on which wood they like the best aesthetically. You could be very disappointed in how your kitchen feels if you don’t love the look and chose the wood solely based on its durability.
One more thing, for many years white pine furniture was “distressed” at the factory meaning they actually beat up the wood prior to finishing it. They did this because the pine could damage easily during manufacturing and intentionally distressing it eliminated complaints from customers. It gives the cabinets a warm “old-world” look that many clients find very appealing (not to mention practical since if they ding a cabinet it doesn’t stand out like a sore thumb!). This distressing is commonly available on all hardwoods nowadays and we often do it at The Cabinet Guy for our clients.
For those of you who want to know more the website Woodgears has a great layman's review of the impact resistance of many woods and other materials. Click here to see the article. And as always, if I can help you in any way do not hesitate to email me at firstname.lastname@example.org.