There are also exciting developments and technologies that are stretching the performance of the base material – transforming the properties of timber, for instance, so that it acts like another material.
Timber, of course, has been used for millennia, and prior to the 20th century, many of the products that industrial designers are currently responsible for – furniture, household products and transport – were hewn from locally grown materials.
A variety of timbers were used, for furniture (chairs, tables, beds), tools (handles, shoe lasts), food preparation (fruit bowls, utensils), washing (washboards and wringers, clothes racks, clothes pegs), ablution and personal grooming (all manner of brushes for hair, teeth and shaving; combs), and transport (wheels, carriages, coaches, walking canes).
Wicker and willow were also woven into baskets for the carriage of a multitude of items. Many of these products have since been refashioned utilising newer materials – predominantly plastics and metals – but in the discussion of sustainability, we are revisiting these ‘grown’ materials as in many cases their environmental impact is significantly lower than that of their modern material counterparts.
Growing trees takes a long time – particularly for high-quality timber. In processing the tree to make timber there is often a lot of waste – that is, a large proportion of the tree is not converted to timber, as typically it is only the trunk and principle branches of the tree that are used.
Seasoning of the timber also takes time. Traditionally this process involved stacking the sawn timber and air-drying over several months, but more commonly the seasoning time is reduced by using kiln-drying techniques.
The process of harvesting, processing and manufacturing timber can be a little wasteful, laborious and time-consuming. Additionally, if the timber is to be used in an outdoor environment it is usually chemically treated with a cocktail of poisons (eg copper, chrome and arsenic, or CCA) that protect the timber from fungal, pest and rot attack.
Yet the environmental virtues of timber are often promoted. A particularly interesting argument put forward in more recent years with the prospect of carbon tariffs and carbon trading is the amount of carbon that can be ‘stored’ in the timber.
That is, during the life of the tree, CO2 is absorbed and converted to cellulose-based material (wood), and therefore so long as the timber is not burnt or allowed to decompose, the carbon is locked away. In this way the carbon footprint of timber is virtuous indeed when compared to many other materials.
One curious example is the debate over the use of cork versus aluminium screw caps to seal wine bottles. Without going into the functional or emotional argument about which is better for the wine or the consumer, the environmental debate is interestingly contentious.
The majority of Australian wines now use screw caps rather than cork. Cork is harvested form the Quercus suber oak tree, by peeling away the cork bark. Because the trees are not cut down in this process they continue to absorb CO2, thereby helping to offset any carbon-emissions in the processing of the cork products.
Conversely, in the production of aluminium screw caps the CO2 emissions are much higher (in the order of four times) as aluminium smelting is extremely energy intensive. Aluminium, however, is produced locally whereas cork is imported from the other side of the world, hence the CO2 emitted in transporting the corks should also be factored into the eco-footprint.
Then, considering that the top of the bottle with the cork in is often wrapped in an aluminium foil anyway, the environmental argument can become a little academic. In short, there is always more than one argument to support the selection of one material over another.
Hemp is similarly contentious, largely due to its association with marijuana (hemp and marijuana both derive from the cannabis plant: hemp is obtained from the stalk, whilst marijuana comes from the leaves, flowers and seeds). But not all plants within the cannabis family contain high levels of the active THC compound that is sought after for use as a drug, and at one time hemp was widely grown.
Indeed, hemp was the mainstay of textiles prior to the Industrial Revolution – providing fabric for clothes, towels, sheets, sails, tents, curtains and rugs, amongst other things. Its modern uses are more varied than textiles, however, and include bio-fuels, paper, oils and lightweight building products.
Hemp is currently an under utilised resource that offers many benefits over other natural and synthetic fibres – especially in regard to its environmental virtues. It grows quickly, is cheap and produces a light and strong fibre.
It grows using a fraction of the water required by cotton plantations – something of particular significance to Australia, given the Federal Government’s buy-back of irrigation permits in southern Queensland to help increase water levels in the Murray-Darling Basin.
The Hemp Industry Bill 2008, passed by the New South Wales Parliament, permits the industrial use of hemp, so it is expected that there will be a greater uptake of hemp in manufacturing.
Hemp can also be used to form a biopolymer known as hemp plastic or Plasticana, which can be formed into all manner of objects in much the same way as any other thermoplastic.
Another biopolymer is cellulose acetate, which derives from cellulose material extracted from trees. This plastic can be translucent, has good wear resistance and can self-polish, making it ideal for things like spectacle frames. The polymer can also be dosed with a scent – a perfume, for instance – that provides interesting opportunities for designers to create more sensorial products.
Novel approaches to enhancing the properties of timber are in development.
A number of researchers are working in the field of timber modification; amongst them are Forest Research in New Zealand and the Australian Cooperative Research Centre for Wood Innovations, who are, amongst other things, using microwave technology to modify timber for rapid seasoning and for bending (comparable to steam bending).
At high temperature the structure of timber can be modified, and Retiwood is an example of such a product, whereby timber is heat-treated as a preserving technique. The process, developed by Ecole Nationale Supérieure des Mines in Saint-Etienne, France, is environmentally friendly as it does away with the need for chemical treatments.
Some recent developments are now commonly available, including Eveneer – a beautiful product that is made by adhering many veneers together and then counter-slicing off very thin sheets of the material to create a veneer comprising multiple layers.
This process allows all manner of decorative effects – dark and light veneers can be stacked to produce a very fine contrasting final veneer, or the layers can be differently coloured to create interesting (if somewhat gaudy) patterning.
The process also results in a more stable veneer that is easier to book-match together, providing an invisible join over large areas. From an environmental perspective this material has merit because it allows smaller pieces of veneer and timber (often off-cuts) to be brought together to make a very decorative final material.
Also making more from less, the Indurite process alters the properties of fast-growing plantation timber (usually pine) to produce a more resilient and hard-wearing timber that can compete with slower-growing hardwoods.
The process works by re-impregnating cellulose derived from trees back into the timber to produce a denser material. The virtue of this process is that it adds mechanical strength and stiffness, greater durability and better machining properties, thus adding significant value to the material.
As the additive to the timber is its own cellulose, the final product has environmental merits – perhaps the most significant from a sustainability perspective is that, as it only takes twenty or so years to grow and harvest the softwood, several harvests can be gathered in the same time it would take to grow trees that provide similar strength and durability.
This product is commercially available under the name Green Seal.
The speed at which plantation pine grows is nothing like the growth rate of bamboo, however. In the right growing conditions it’s reported that bamboo can grow a metre a day – a phenomenal rate indeed.
Typically it grows more slowly, as optimal conditions are not always available. Bamboo is readily used in its natural state for all manner of bespoke products, including musical instruments, construction scaffolding and bicycles and other modes of transport.
Bamboo is also processed into composite boards and can be used much like standard timber – one common application is for flooring boards. Its ability to be stripped into a fibre and woven into baskets and other products provides other important ways of using this material.
Weaving with natural fibres is common to many cultures, particularly island cultures where there are fewer material resources – many ingenious applications, uses and processes have emerged from the plant-based materials to hand. When considering sustainability, there is much to learn from the versatile and clever ways in which vernacular materials and resources have been used in these cultures.
There are ancient traditions and techniques of wicker-work – a generic term referring to the weaving of cane (young stems of tropical plants such as bamboo), twigs or reeds – and many plants are used, including rattan (a tropical climbing palm), jute (a fibre sourced from the course bark of a tree), hemp and flax.
There are also textiles derived from plant materials that do not require weaving. In Africa, for instance, a fabric called bark cloth is made from the crushed bark of Ficus natalensis which is layered and flattened to create a nonwoven textile.
Another way to utilise plant-based fibres, strands, chips and particles is to compress them under great pressure to form a dense fibrous material. Of course there are many modern versions of this process, including all of the fibreboards (chipboard, MDF, hardboard and so on), but some of the more traditional and unusual materials hold some interesting opportunities for sustainability.
Kirei Board, for instance, is a strong, lightweight board made from the waste stalks from the sorghum plant after the grain has been harvested. The stalks are heat pressed with an adhesive to form the material. In a similar fashion, straw, coconut fibres and seagrass have also been used to produce boards, usually for insulation.
As children most of us made papier-mâché bowls and objects. If the same material is compressed under intense pressure into a mould, it produces a remarkably strong and lightweight material.
Importantly it is made from recycled paper of which there is a plentiful supply. Another application using recycled paper is paper foam – an interesting insulation and packaging material made by crushing recycled paper to obtain fibres that are then mixed with a natural resin (starch).
The resultant paste is then heated and expanded to create a foamed material that’s very similar to expanded polystyrene or expanded polypropylene.
One of the most unusual plant-based materials is a compressed board made entirely of tea. The tea ‘brick’ is made by compressing tea leaves into a die in a 60-tonne press. For more than 200 years these bricks have been used as a space-saving way to transport tea, and in the past they were sometimes used as a form of currency.
There may well be other ways to use compressed leaves, coffee grinds or other waste ground or fibrous matter in a similar fashion to the compressed tea brick. Another interesting thing about the tea brick, apart from its texture, is its amazing smell.
There are real possibilities for the creation of ‘products’ from discarded matter with inherent or added fragrance. Of course, timber materials have naturally dominated over other materials for their olfactory qualities, and probably always will, but design has typically concentrated on the visual allure of materials, and not really exploited the other senses.