About woodWhen you use wood for interior decoration, you create a personal and warm home. No piece of wooden furniture or accessory made of wood is exactly like another, since the grain and the material itself are always unique. Wood fits any home, regardless of style and period. Wood products offer a soft and natural feeling. It is not only wonderful to touch and great to live around, but it also smells good. Generally speaking, wood is a very strong material in relation to its weight. Wood products and accessories from JUST WOOD, for instance, seem light compared to similar products in other materials. Below follows a description of the structure and characteristics of wood in general, then a description of the types of wood and wood materials used in products from JUST WOOD. This is reading for those who are curious!
The structure of wood
All plants are made up of cells. These are enclosed by a so-called cell membrane, and around it there is a strong cell wall which fixates the form of the plant. The smallest part of the cell wall is cellulose (40-50%), which has a chemical connection to sugar and consists of long chain molecules. In between these chains, there is lignin (20-30%), a wood substance which binds cellulose. When exposed to sunlight, lignin turns yellow, and this can be seen in any timber or paper where lignin remains, for instance in paper used for newspapers. Cellulose and lignin function together in the same way as reinforced concrete, in the sense that cellulose acts as reinforcement and lignin as concrete. Other component parts are hemicellulose (20-30%), the structure of which resembles cellulose, and a small amount of other substances, such as for instance resin. The amount of cellulose is about the same in hardwood and softwood, but hardwood contains less lignin and more hemicellulose.
The wood of hardwood and softwood has the same structure in principle, but individual cells are partly different in form. Fiber (those cells that can be used for pulp, for instance, and that provide wood with stability) constitutes the major part, in coniferous trees 90-95% and in for instance birch 60-65%. The fibers of hardwood are also in most cases shorter than the ones of softwood; birch fibers are 1 mm and pine fibers are 2.5 mm in length.
Early wood – Late wood
In our climate, tree trunks only grow part of each year. The cells also grow in different ways at different points in the growth cycle, and this is why we speak of early wood and late wood. Late wood completes the growth period and marks the so-called growth ring. Late wood consists of cells with thick walls, and early wood consists of cells with thin walls. The difference between early and late wood is marked with varying obviousness for different trees. Pine trees, for instance, have very conspicuous growth rings, while the growth rings of aspen are barely visible. (See for instance the KAKU bag made of Japanese cedar (softwood) compared to the SNAKE hook made of beech (hardwood)). For soft wood trees, the share of late wood is relatively consistent from one year to the next, while the share of early wood varies in relation to growth. This means that fast-paced and substantial growth also means more early wood and lower density. Hardwood trees are divided into semi-ring porous and diffuse porous dep ending on how vessels are distributed in the wood. In semi-ring porous hardwood trees like oak and ash, very large vessels characterize the early wood, while the late wood contains only smaller vessels. Since the summer wood contains smaller vessels, more growth means a more compact wood, in other words higher density. For diffuse porous hardwood - birch, beech, maple, and so on – vessels of approximately the same size are evenly distributed across the entire growth ring and the cross-section surface of the tree. It can sometimes be hard to distinguish a clear boundary between spring and summer wood, and thus the growth rings can be difficult to see. Since the vessels are evenly distributed, the density is not impacted by changes in growth.
The small lines that go from the center of the tree trunk to the bark are called rays. Their task is to transport water and nutrients radially, and to store nutrients. It is easy to see so-called rays in hardwoods like oak and beech, but they are not visible in softwood.
Heartwood / Sapwood
In a living tree, transportation takes place in cambium (between the inner bark and the wood) and in the outer growth rings. The inner part of the trunk, the heart, contains 5-6 times less water and is expended as far as the tree is concerned although it contributes to stability. The outer growth rings, which are also called sapwood, are in many cases lighter in color and have other characteristics than the heart. The sapwood wood contains some living cells, although most of the cells are normally dead. This is different from the heartwood which is completely dead, and often resin-filled. The sapwood wood takes care of transporting water and minerals from the root to the leaves – this is why sapwood wood feels wetter than heartwood in a newly harvested tree. As long as the tree is growing, the heartwood is more vulnerable than the sapwood wood. This is because the sapwood wood is alive and can activate defense systems. This effect explains why old trees can sometimes become hollow. In those cases, the sapwood wood keeps renewing itself, while the heartwood disintegrates over time. However, when the tree is not growing, it is the sapwood wood that is less resilient when it comes to withstanding insects and fungi.
The characteristics of wood
Most types of wood are lighter than water but there are some that do not float in water, one example is ebony. The lightest wood of all is balsa tree, but it has low strength and is very soft (it is easy to push a pin deeply into a piece of balsa wood). For carving, linden wood is particularly suitable, since it is easy to work it using cutting tools. Pine and spruce are used for flooring. Pine is stronger and more stable in form when there are changes in humidity compared to spruce, but darkens when exposed to light. For floors which are not going to be covered by linoleum or plastic carpets, spruce is therefore often the preferred alternative. Spruce can sustain bending better than pine. This explains why spruce was a common material for making old-fashioned massive skis. For the same reason, spruce was traditionally used for trusses and roof ridges. Birch and beech are harder and stronger than pine, but not as hard and strong as oak. The specific characteristics of each type of wood depend on where and how a tree grows. Already when the tree is growing up, it is possible to influence the quality of the timber through new and old forestry techniques. Wood from the same type of tree can have radically different conditions. It can vary in hardness, be straight or crooked. Timber sawed from a log can be very different in terms of weight compared to another quantity of timber of the same type depending on individual growth conditions. One of the reasons can be if it has grown more rapidly or more slowly.
- Heat characteristics – Wood has low thermal conductivity and high heat capacity, which makes it a good material for building and also suitable as an isolator, for instance in pot handles.
- Permeability – Wood is a porous material, and as such it has high permeability, which means the ability to absorb liquid. It is important to be careful with wooden accessories and keep them away from water, for instance avoid wearing them in the shower.
- Electric characteristics – Dry wood does not conduct heat. Damp wood above the fiber saturation point (30%) is conductive.
- Acoustic characteristics – Wood has good silencing qualities and improves the acoustics of a room. Wood is greatly suitable as a material for making music instruments. Tap your wood products and listen to the sound!
- Smell – Wood smells good. Some types of wood have a more intense scent than others, for instance juniper and larch. Spruce and beech have almost no discernible scent.
- Color – The color of wood varies a great deal between different types of tree, but also depending on humidity, heart/splint, age, processing and surface treatment. When exposed to light, most types of wood darken (“mature”) to a greater or lesser extent. Pine, for instance, darkens much more than aspen. Some of the products of JUST WOOD are untreated, and therefore they will darken and achieve a beautiful patina over time. One example is the BASIC no 1 necklace.
Description of wood materials used in the products of JUST WOOD
Different types of wood and wood materials differ in appearance and feeling as well as qualities, availability, and price. Below follows a description of those types of wood and wood materials that have been used for JUST WOOD products.
The ash is one of our most nutrient-demanding types of trees, and it grows best in deep, calciferous mold soils. An ash tree can reach a height of 25-30 metres. The crown is open and domed, and especially the outer branches are clearly directed upward. The bark on the trunk is smooth, light grey to olive grey-green. Leafing takes place late, often later than all other deciduous trees, and the leaves are composed out of around ten small leaves which are oval like lancets and vaguely serrated. The natural habitat of the ash in Sweden extends to Värmland and Gästrikland, which corresponds roughly to the northern boundary of the oak tree. The wood is hard, tough, and semi-ring porous which means clear differences between early and late wood. The rays are small and barely visible. The color of the sapwood varies from light yellow to light grey. The heart is darker. The timber is tough, strong, and relatively easy to work. Due to its toughness and strength, ash has traditionally been used for
wheels and tools. Today, ash is used for parquet flooring, banisters, furniture, and interior decoration. The ash has had a boost in the furniture industry over the last 5 years. I myself think that ash is an exceptionally beautiful type of wood, with its distinct pattern of early and late wood. An example of a JUST WOOD product made of ash: the BochL tray.
Hornbeam / White beech
The Hornbeam has a limited need for access to nutrients, but prefers well-drained mold soils. The Hornbeam can reach a height of 25-30 meters, has a domed crown, and often multiple trunks. The bark is light grey and smooth with lengthwise rounded ridges. The leaves are narrowly eggshaped and pointed with a doubly serrated edge. In Sweden, it can be found sparsely in the southernmost parts. The wood is diffuse porous, yellow/white, lacking a heart, heavy, tough, and hard. The growth rings are distinct and characteristically curvy. The wood is homogeneous with no visible vessels, which provides a massive and smooth surface. The timber is the heaviest, hardest, and strongest of the Nordic types of wood. Historically, it has been used for products which have been exposed to heavy wear and pressure, such as plugs, wood screws, cylinders, mangle rolls, and machine parts. Today the timber is used for tool handles, table tops, wooden clubs, and piano keys. An example of a JUST WOOD product made of Hornbeam: colored wooden beads in KUL accessories (earrings, necklaces, bracelets).
Birch – Vårtbjörk+Glasbjörk
The birch is common almost everywhere in Sweden. The white birch prefers damper soils than the silver birch. The white birch has a straighter and stiffer way of growing compared to the silver birch, its branches are less droopy, it has rounded and singly serrated leaves, and a smooth and more shiny white bark than the silver birch. White birch is sold in the same way as silver birch; they are not distinguished by species but just labelled as “Birch”. Birch wood is differous porous with growth rings which are vaguely visible. The wood is yellow-white to yellow-brown and lacks a distinct heart. The rays are hardly visible. Birch is the wood that has the broadest range of application of all Swedish types of wood. Traditionally, birch has been used for furniture, household items, tools, and appliances. Birch has been the most common type of wood in furniture manufacturing. Birch is also used for the surface layer of plywood, and for panel. Birch wood is greatly in demand for pulp, its high value as fuel i s well known, and its bark is attractive for craftspeople.
Examples of JUST WOOD products made of birch: the NAMO and PANTO sunglasses, the RETRO tray, the LASTU baskets, the OKSA hook, the JUGEND-, EMPIRE- necklaces and the PRINSSI candlestick.
Beech – European beech
The beech is a tree which prefers shade and deep mold soils. The ground should be hilly and amply watered. In closed populations, the beech has a straight trunk and a high crown, while a single beech has a wide, low crown. The bark is light grey to grey, thin and smooth. The leaves are egg-shaped with slightly serrated edges. The beech is common in Sweden as far north as Västergötland, but is cultivated/planted almost only in Skåne and Blekinge. Beech wood is differous porous with vague growth rings, and it is heavy and hard, yet easy to split. When newly harvested, it is white/yellow, but later turns reddish, which is why it is called “red beech” in Sweden. Another characteristic trait is its distinct, thin, brown rays. The beech is dense, hard, with straight fibers, easy to split, has good qualities for turning and was therefore used traditionally for wagons, toys, and tools. Beech wood does not absorb fat, or emit smell or taste, and is therefore used for household items such as ice cream sticks. B eech can also be bent by means of steam, which has been done for a long time to make bending furniture like chairs. Another area of application is furniture, interior doors, and parquet floors. Examples of JUST WOOD products made of beech: the SNAKE hook, the WOODLANDS hook, the RAILROAD shelf.
The oak has a deep root system and prefers deep clay or mold soils. There are two species of oak in Sweden, Skogsek (Quercus robur) and Bergsek (Quercus petraea). An oak growing freely has a very wide and open crown with thick, gnarly and almost horizontal branches. In forest populations, it can have a straight trunk. Its bark develops over time into a grey and rough bark with lengthwise furrows. The leaves have very short stems, and are usually sleek. In Sweden, the oak is common in the middle and sounth of Sweden. The two species of oak look similar, they are semi-ring porous and the pores in early wood are broad, organized into rings, and clearly visible. The rays are also visible. The splint wood is light yellow-grey and clearly separated from the heart which is grey-yellow and later light to dark brown. Oak is hard and strong, and its heartwood is very resistant to rot. Traditionally, therefore, oak has been used for a long time for building ships and structures having to do with water. O ak wood has also been used for bridges, banisters, fences, and other types of outdoor construction. Throughout history, massive oak and oak veneer have enjoyed a high status as material for interior decoration and furniture. Wall paneling, massive doors, and furniture made of oak have been used for a long time to lend banks a high status. The office furniture industry used only oak until beech and birch gradually took over the market. Examples of JUST WOOD products made of oak: the LASER necklace and earrings.
The linden thrives on clay, nutrient-rich, and well-drained soils. It provides a great deal of shade because of its densely structured crown. In young trees, the bark is smooth and brown-grey, while old trunks form a greyish bark. The leaves have long stems and are obliquely heart-shaped, serrated with a prolonged tip, and distributed apart on the branches. The most common type of linden in Sweden is Tilia cordata (Small-leaved Linden). It occurs naturally in small populations in the middle and south of Sweden. It is not particularly common. There is also Tilia platyphyllos (large-leaved linden), which is common in other parts of Europe but which can only be found in a few places in Bohuslän in Sweden. The wood is light yellow-white and diffuse porous with a tendency towards semi-ring porous. The pores are small and evenly distributed across the growth rings which are vaguely visible. There is no visible difference between splint and heart. The timber has a distinct acrid scent. Linden wood is soft, l ight, homogenous, with straight fibers, which makes it suitable for carving and sculpture. For example, the KORPAR of JUST WOOD are carved out of linden. Many medieval church sculptures and the sculptures of the Royal Ship Vasa were made out of linden. Linden is also used for fine woodwork and wood turning such as brushes, toys, music instruments, and blinds.
The maple thrives on deep, well-drained soils, and demands a great deal of light. When solitary, the maple has a leafy crown with a rather irregular and crooked set of branches. In closed populations, it can develop straight trunks with a great part of the trunk free of branches. The bark is smooth, but over time it splits lengthwise. The color of the bark varies from grey-brown to almost black. The leaves have a characteristic laciniated shape and turn to beautiful yellows and reds in the fall. The wood is diffuse porous, hard, medium heavy, and elastic, and usually uniform in structure with straight fibers. The wood is white to yellow-white and usually has no distinct heart. The growth rings are vaguely visible. Massive maple wood has been used for fine furniture and turned objects. The timber turns smooth and soft when polished. Maple spoons were very durable, and handles for axes and rakes made out of maple were said to “cause fewer blisters than other types of wood”.
Examples of JUST WOOD products made of maple: the RETRO kitchen tissue holder, the PUISTO cutlery and cake slicer.
MDF means Medium Density Fibreboard. MDF is a wood fiber plate for which wood fibers have been mixed with glue and water and pressed into a board. Since the material consists of finely chopped fibers, the surface is smooth and even, which means that the material is very suitable for painting. Consequently, it is often used for painted woodwork. The MDF plate is made out of 100% softwood, which means a light color.
JUST WOOD products made out of MDF: the RETRO cutting board.
Paper is made in the pulp and paper industry from fibers containing cellulose in the shape of pulp. The dominating raw material for pulp production is wood, but other plants such as hemp and cotton can also be used. There are different methods for making pulp, and they can be divided into mechanical and chemical production methods. Mechanical methods have been used since the 1840s. The fibers are separated from each other mechanically by means of mills (refiners) or grindstones. This paper will be weaker than paper made from chemical pulp since the share of cellulose is lower - which in turn is due to the fact that all parts of the wood, especially lignin, remain – but the mechanical methods provide a high pulp return, usually more than 85-90%. The lignin in the paper means weaker bonds between fibers and the paper turns yellow when exposed to light.
The two most common chemical production methods are the sulphite process and the sulphate process. The sulphite process was the dominating method for pulp production from the late 19th century until the 1940s. Wood chips are boiled in sulphur dioxide solutions, and the process results in a relatively light pulp, but not as strong as the pulp resulting from the sulphate process. The sulphate process has been the most commonly used since the 1940s and it yields stronger paper than other methods. The process means that wood chips are boiled in white caustic, a strong alcaline solution of sodium sulphite and sodium hydroxide. Recycled paper is also used for making recycled fiber pulp, used for paper and cardboard with partly lower demands for quality.
Tisue paper is made partly from bleached virgin wood fiber (pulp) for high quality, partly from recycled fiber for lower quality. The weight of tissue paper is lower than for other qualities of paper, usually below 30 g/m² all the way down to 12 g/m². The consumer products are manufactured through converting the large paper rolls from the paper machine, to finished products. The end product is often made in several layers, for instance paper napkins. The end product is often printed or stamped with different patterns, either for decoration or to keep the tissues together if there are several layers.
JUST WOOD products in tissue paper: the RETRO napkin.
Wood fibers are used for a great many products which are not usually associated with wood, such as dish cloths, clothes, fuel and so on. The wood fiber has then been processed in different ways and mixed with some other material to make a wood-based composite.
Product from JUST WOOD in wood-based composite: the RETRO dish cloth with 50% cellulose and 50% cotton.
Source: primarily Nordiska Träd och Träslag – Dahlgren, Wistrand and Wiström