Our oak lexicon

What is acetylated wood?

Acetylated wood is wood that has undergone a chemical modification process using acetic anhydride to reduce its susceptibility to decay caused by wood-destroying fungi and insects, thereby significantly extending its service life in outdoor applications. Through this process, the molecular composition of the wood is permanently altered, resulting in improved physical and mechanical properties such as dimensional stability, increased density and hardness, and enhanced weather resistance. Since acetic anhydride and the acetic acid produced during the reaction are non-toxic, acetylated wood can be utilized and disposed of without restrictions.

What is bending strength?

Bending strength, also known as flexural strength, describes the ability of wood to resist bending stress without breaking. Bending strength is an important measure for the load-bearing capacity and stiffness of wooden components and is expressed in newtons per square millimeter (N/mm²).

Definition of Bog Oak

Bog oak refers to subfossil oak wood (Quercus spp.) that has been preserved over centuries or millennia in bogs or swampy areas. During this time, the wood undergoes chemical transformations, primarily caused by the reaction of tannins in the wood with iron compounds from the bog water.

The result is a unique material characterized by a dark coloration, increased density, and enhanced hardness. Bog oak is not a separate type of wood but rather a condition of oak wood preserved under specific environmental conditions. It is highly valued in art, craftsmanship, and research due to its rarity and distinctive aesthetics.

What is Brinell Hardness?

Brinell hardness is a standardized method for measuring the hardness of materials such as metals, plastics, and wood. It indicates how resistant the material is to mechanical indentations and is commonly used in the metal industry and material testing. During the measurement, a steel ball with a specified diameter and constant force is pressed into the material. The resulting indentation is measured and used to calculate the hardness value, known as the Brinell hardness number (HBW), which is given in N/mm².

What is Butt-cut lumber?

Butt-cut lumber, or original log (equivalent to "whole log"), is a type of wood that retains its natural edge or bark (unsurfaced) after being sawn lengthwise from a tree trunk. This process preserves the original thickness and structure of the wood, even after storage, drying, and further processing.

What does cell collapse mean in wood?

Cell collapse describes a defect in wood processing in which the cells in the wood tissue irreversibly collapse during drying or under certain mechanical conditions. Wood affected by cell collapse can exhibit strong deformation, sometimes accompanied by broad, honeycomb-like internal cracks that render it largely unusable. This type of damage is often recognizable by irregularly sunken surfaces that can appear corrugated, along with significant distortions in the cross-section.

What is compressive strength?

Compressive strength characterizes the ability of wood to withstand axial compressive loads without failing. It is an indicator of the load-bearing capacity of wooden components subjected to compressive stresses, such as columns, piles, and foundations.

Definition and Functionality

A drying kiln is a closed, climate-regulated facility in which wood is dried by controlling temperature, humidity, and air circulation. The goal is to adjust the wood’s moisture content according to its intended use and to achieve a uniform moisture distribution throughout the entire cross-section.

The drying process is controlled through the interplay of various physical processes, including the evaporation of free water from the cell lumina, the movement of water through cell walls, and the gradual reduction of the wood's overall moisture content. Modern drying kilns are equipped with sensors that monitor temperature and humidity, allowing precise control over the drying process and helping to prevent damage to the wood.

What is Equilibrium Moisture Content?

Equilibrium moisture content (also known as EMC) refers to the moisture content of wood that stabilizes after a certain period under constant environmental conditions. In this state, the wood neither absorbs moisture from the air nor releases moisture to the air.

What means flat cut, crown cut?

Oak sidewood from large logs. In this selection OAK flat cut/crwon cut we take only the side boards of a log. In this form there is no medullary rays shown. No straight grain. The edge of the tree shows a heava wane. The difficult part of drying the flat cut boards is the surface without cracks. A very carefully predrying under roof and the modern vaccumdrying allowes us a gently kiln-dried result. The oak sawn timber produced from the flat cut/crown cut OAK board shows the unique view. The finished piece of furniture, the high-quality floorboards, or the wall cladding in its perfect look.

What is the FSC® Label?

The FSC® (Forest Stewardship Council) is an independent, non-profit organization that sets global standards for responsible forest management. FSC-certified forests and wood products must meet strict ecological, social, and economic criteria based on the so-called Principles and Criteria of the FSC. For consumers and companies, the FSC label signifies that the wood used comes from sustainably managed forests and that full traceability along the supply chain is guaranteed.

What is the Janka Hardness?

The Janka hardness is a method for determining the hardness of wood, indicating how resistant the material is to indentations. It measures the amount of force required to press a steel ball with a diameter of 11.28 mm halfway into the wood. The required force, measured in kilonewtons (kN), provides information on the wood's resistance to pressure marks. The higher the Janka value, the harder and more resistant the wood.

What is Live Edge?

The live edge, also known as waney edge, natural edge, bark edge, or by the German term Baumkante, refers in woodworking to the natural edge of a wooden board or log. It replicates the naturally grown line of the tree trunk, thus preserving the original shape of the tree, including the bark and sapwood. The live edge imparts increased naturalness and individuality to the wooden workpiece, which is appreciated in both modern and traditional designs.

What does wood with a live edge mean?

Wood with a live edge, also known as "live edge" wood, refers to wood products where the natural shape and contour of the tree trunk are preserved. Unlike fully trimmed wood, live edge wood retains the natural bark and outer form of the tree. This gives the wood a rustic and natural appearance, which is highly valued in furniture making and architectural applications.

How is sawn timber measured?

The measurement of sawn timber is an important process in wood processing to determine the dimensions for sale and further processing. There are different methods depending on whether the timber is unedged, partially edged, or fully edged. Each of these categories has specific rules for measuring width, handling wane (bark edges), and accounting for splits.

What is Mass Density?

Mass density or particle density of wood describes the density of the pure wood material without any pores or cavities. It measures how heavy the wood itself is if all voids (lumina) within the wood were compressed to be nonexistent. The mass density is nearly the same across all wood types and is approximately 1.50 g/cm³. This value relates to the chemical components of wood, such as cellulose and lignin, independent of natural pore structures or external factors.

What is a rift cut?

The rift cut, also called radial cut or mirror cut, is a special way of cutting wood. The rift cut only produces planks with vertical growth rings, which result in high strength and a uniform tensile and shrinkage ratio.

What is sapwood or heartwood?

When people think of wood, they often imagine a uniform material. In reality, however, a tree trunk consists of different zones that vary in their characteristics, depending on the tree species. In general, we distinguish between sapwood and heartwood, each fulfilling important functions in the tree and bringing its own specific properties for woodworking.

What is a sawn veneer

Sawn veneer is a thin sheet of wood that is obtained by sawing a tree trunk. In contrast to other methods of producing veneer, such as peeling or slicing, sawing produces a rougher surface and a more pronounced wood structure. This method of production preserves the natural beauty and characteristics of the wood, which makes it particularly attractive for high-quality applications.

What are the Shrinkage and Swelling Measures in Wood?

When we talk about wood, many people first think of warm colors, a pleasant feel, and a sense of nature. But wood can do even more - it “works.” This is precisely where the shrinkage measure and the swelling measure come into play. These two terms describe how much wood changes when it absorbs or releases moisture. And it’s not as complicated as it might seem at first glance.

What is solid wood?

Solid wood refers to wood that is cut from a single piece of the tree trunk without being broken down into smaller pieces or combined with other materials. This natural form preserves the original structure and grain of the wood and makes it a favoured material in wood processing.

What does "square-edged" mean?

Square-edged refers to a board that has been cut along the grain on both sides, resulting in a consistent width along its entire length. The processor of sawn timber has a significantly more accurate yield calculation when purchasing parallel-edged wood. This makes it easier to estimate costs for molding or furniture production. It's a crucial factor when comparing prices effectively.

What is tannic acid?

Tannic acid, also known as tannin or tannin, is a fascinating class of polyphenolic compounds found in many plant species, especially trees. This substance is not only an essential component of plant defence mechanisms, but also a key element that contributes significantly to the longevity and robustness of wood.

What is white cloud discoloration?

White cloud discoloration is an undesirable phenomenon that can occur when drying wood, especially oak. It manifests itself as uneven, cloud-like light spots on the surface of the wood. This discoloration usually occurs when the wood is dried too quickly or unevenly, resulting in different moisture zones. The risk is particularly high when drying in closed kilns without prior air drying, as the wood cannot release moisture evenly.

What is Wood Density?

The density of wood describes the ratio of its mass to its volume and is given in kilograms per cubic meter (kg/m³). It indicates how heavy a specific volume of wood is and plays a key role in assessing properties like strength, hardness, and insulation capacity. Wood density varies depending on the wood type and moisture content and is an important factor in selecting wood for specific applications such as construction or furniture.

What is wood moisture?

Wood behaves hygroscopically, i.e. it absorbs water from the surrounding air and releases it again. The water content in wood is referred to as wood moisture and is expressed as a percentage of the dry weight. This value has a considerable influence on the usability, durability and workability of wood.