Technical Corner

Different Species

WOOD: Answering the Call

Is there anything that can be done to make wood a more stable product?

Is there any way to make some woods such as Ash, Aspen, Beech, Birch and Poplar more useful to the Architect and Designer?

Can you make wood more durable and retain color consistent throughout the wood for Commercial Projects?

Is there a natural way to make woods more insect repellent and less susceptible to rot?

Based on research that was started in Finland and France in the 1990’s there is a technology that helps answer all of the above questions.

Researchers found that when you take the basic building blocks of wood – Cellulose, Hemicellulose, and Lignin and super heat them there are some chemical reactions that take place that alter the behavior of wood. More…

 

Humidity-MCWood Movement, You Can’t Stop it

Most flooring contractors and finish carpenters are aware that seasonal changes in humidity cause trim and flooring to shrink in the winter and expand in the summer. But few realize that the expected movement can be accurately predicted and potential problems avoided. With a moisture meter and an understanding of wood movement, most wood movement problems can be avoided.

The Nature of Wood

Wood is hygroscopic, which means its moisture content (MC) will fluctuate based on the relative humidity (RH) of the surrounding air. As humidity increases, the MC increases, and the wood expands, and as the humidity decreases, MC decreases, and the wood shrinks. This relationship is referred to as Equilibrium Moisture Content (EMC), and can be accurately predicted.

The moisture content of wood is tied directly to the relative humidity of the surrounding air. The higher the relative humidity, the higher the MC of the wood; period. If you’re installing wood flooring that’s recently been transported, or installed on a job, it might take a little while for the material to reach its equilibrium moisture content (EMC) with the air—in other words, for the wood to acclimate to the humidity level for the climate around the wood: the wood may take on more moisture or it may dry out. For example, if wood at 10% MC is exposed to a low 25% RH, the wood will dry to 5% MC (and shrink as it dries).

More…

 

 

Fuming Oak

Fuming an Aged Old Process Given New Life

Much of the beauty of Gustav Stickley’s Arts and Crafts furniture is derived from the careful wood selection and his insistence on finishes that didn’t obscure the natural look and feel of the wood. The unique design of his Morris chair is trademarked by beautiful character marks of quarter sawn White Oak that was not to be obscured but enhanced by his fumed finish process.

He devised this finishing process to achieve the low-key, almost sensual look and feel he wanted.

Fuming – An age old method that has been resurrected to once again reveal the beautiful grain of wood. This process gives wood a distinctive brown appearance and highlights the rays of quarter sawn Oak.

Fuming wood flooring chemically changes the color of the wood. The procedure involves putting the Oak in a closed chamber in which commercial grade ammonia is introduced. This chemical is a commercial grade of ammonia that is stronger than the household grade and produces a stronger effect. The darkening effect of the ammonia is a chemical reaction with the tannins that are naturally in the wood’s chemical make-up. It is not the application of the ammonia to the wood, but rather the fumes reacting to the tannins in the wood that produce the color change. More…

 

Different Cuts of Wood

 

Different Cuts of Wood

This old proverb advises to cut and stitch the cloth according to the material available. Cutting lumber can be compared to this same idea. What will the log yield? What is the desired look, style, pattern sought after. It can all be altered in the way that you cut the log.

Quarter Sawn, Rift Sawn, Plain Sawn, Live Sawn

Have you heard these terms and wondered what they mean. We often struggle to define these terms however I will try to explain them in a way that works for me.

Let’s take a look at Oak as a species. Early in our Country’s history Oak trees were and still are very prevalent. The cell structure of Oak is ring porous with radial rays that can be readily split along the radius of the log. Metal wedges were driven into the logs and split. The log would split along grain lines fairly evenly. To produce planks from these logs a tool called a froe was used.

A froe could be driven into the end grain of the log.

A froe (or frow) or shake axe is a tool for cleaving wood by splitting or riving it along the grain. It is an L-shaped tool, used by hammering one edge of its blade into the end of a piece of wood in the direction of the grain, then twisting the blade in the wood by rotating the handle. The froe used the handle as a lever to multiply the force of the grain, allowing the wood to be sliced (riven) along its grain. More…

 

 

White Oak Reactive FinishesReactive Oils and Finishes

Hidden within the cellular structure of many hardwood species are chemicals that will oxidize and reveal attractive reactions. These unique reactions were developed over 300 years ago, before the advent of pigment for stains or paints. Some of these custom colors can take from 7-9 steps to produce, which replicate the true chemical weathering process that wood experiences in nature. Each step of the process creates a physical change inside the wood on a molecular level. The chemical reactions which take place, such as the oxidation of metallic minerals embedded within the cellular structure of the tree, actually change the physical properties of the wood. In fact, it actually becomes harder and denser, which adds to the durability of the material. Since there is no stain or paint used, you won’t see that artificial, manufactured, uniform look that most wood floors have today. This wood is also finished using a natural oil, which penetrates into the wood instead of sitting on the surface. This accentuates the natural grain and texture of the wood, and as the oil cures naturally within the wood’s pores, it hardens to create a strong surface but allows for easy repairs. Careful experimentation will expose a myriad of colors to the inquisitive and resourceful finisher.

When I think of reactive finishes, I am reminded of our own skins natural tanning process. The amount of pigmentation in each individual’s skin determines whether they will tan quickly or it will take longer timed exposure to develop the degree of tanning desired.

How it works

Woods like Oak, Cherry (heartwood), Mahogany, and Walnut contain a significant amounts of tannins or phenolics which in their electron-rich reduced state tend to be colorless to a very slight yellow. However, rearrangements in electronic structure that occur with oxidation (loss of electrons) cause the compounds to become a more highly colored brown to reddish brown. Some tannins are photosensitive and will oxidize in light with the atmospheric oxygen acting as an oxidizing agent. The reaction tends to be fairly slow, and is the process which Cherry and Mahogany darken over time.

Placing the wood in direct sunlight will speed up this process. Sunlight on cherry causes the color to change much faster as the light acts as a catalyst to speed the oxidizing reaction. A week in the bright sun will darken your wood, but may not be practical for a large project. More…