By Lorrin Windahl.
Well I’m happy to admit that I’m a recent convert to cork. I guess convert isn’t quite the right word, I just didn’t know what a fantastic material it is but now I do. I’ve been enlightened. For those of you who don’t know the story of this highly sustainable material here it is.
Cork oak trees, predominately grown in Portugal and Spain, can live for up to 200 years. After around 25 years the tree needs stripping every 9 years. The bark that is pulled off during this process is what becomes the material that we know as cork. The older the tree is the higher the yield and the quality.
The bark is then processed and cut into uniform, rectangular planks. High quality planks are often used for flooring or wine corks. Poor quality planks and any waste material from the cork manufacturing process is broken down into small particles and turned into agglomerated cork. Pure agglomerated cork is bound together using only heat and pressure in a mould whereas compound agglomerated cork has a binding or adhesive agent added. Additives allow the cork to be enhanced to achieve different performance characteristics.
Pros of cork
- When harvested the tree survives and regenerates its outer bark layer (unlike other timber materials)
- If the bark is removed every 9 years then the tree absorbs 3-5 times more carbon than a similar tree that is not stripped (according to the World Wildlife Fund)
- Waste material can be turned into agglomerated cork
- Excellent chemical and thermal resistance
- Due to cork being made up of hundreds of tiny air pockets it is quite buoyant and will compress & then expand back to its original shape
- Biodegradable & recyclable at its end of life
Cons of cork
- Use of energy and water to process and manufacture the cork
- Synthetic additives such as adhesives for compound agglomerated cork
As you can see, the properties of this material are equally as impressive as the way it is harvested. And although it is likely to have a fair impact on the environment during processing I think that the way that it is harvested, its material properties and that it is biodegradable far outweigh this.
According to the WWF, the move towards synthetic wine corks is having a major impact on the cork industry and the conservation of these precious trees. There is a real concern that these cork oak woodlands will be abandoned if the demand for cork is diminished. But what can we do I hear you ask? Well as designers we can start thinking of cork as a viable material and as consumers we can buy cork products. Thankfully, we seem to be seeing a lot more products made from cork in the market place today. These range from lighting and furniture to footwear and even bags.