What Is Cork And How Sustainable Is It?

Cork is such a versatile and environmentally friendly product that is a must for any maker environment/classroom. If you have a laser cutter, you are good to go. It's burn resistant, so once you have it on the laser cutter it can be cut and then decorated with no chance of flames. More on that later! If you don't have a laser cutter, then a good pair of scissors or a craft knife is all that you need.

We think so highly of this material that we want to make sure everyone knows about it.  We're going to deliver everything we know about cork and hopefully, it will find a place in your future projects. If you are a teacher, this is probably one of the best examples of sustainability available. If you cover Cork and Bamboo, you've covered the best positive examples there are.

  • You can download this guide as a PDF here.


What is Cork:

Cork is the bark from Cork Oak trees and it is harvested from a living tree. Not only does the tree not die, but it will also regrow its bark for future harvesting. A lesser-known fact is that the quality of the bark also improves in quality with subsequent harvests. The third harvest will yield a much higher quality bark than the first. The vast majority of cork oaks come from Portugal and Spain and the trees are Harvested in peak growing season, which is between May and August.

The primary use of cork is to produce wine corks, which are made from the best quality cork available. Once the material for wine corks has been segregated, the remaining is then made ready for all of the other potential uses.

Cork undergoes very little processing, the majority of the time the cork is in storage, laid flat on pallets. The sheets are then immersed in clean, filtered boiling water to remove any impurities and are then stacked flat to dry and cure. The result of this is that the cork is softer, flatter, and easier to work. The cork that is not being used for premium quality wine corks is then ground up and formed into shape with high temperature steam.


Sustainably Harvesting Cork:

On average, tree's can be harvested once the tree is about 25 years old. The trees are then harvested every 9 years. It usually takes three harvests before a tree begins to yield premium-grade cork. The trees are approximately 43 years old at this point. Cork trees usually live for around 200 years and can be harvested more than 15 times.

The main downside of removing the bark from the oaks is that it leaves them more vulnerable to forest fires. The bark is resistant to fire and is such a good thermal insulator that unharvested trees can often survive when all else around them perishes. Aside from that, the trees remain perfectly healthy after harvesting and the next bark growth will be of better quality than the last.

Cork is 100% recyclable.  Not only is cork the best material for a 'cork' for bottles, it also has by far the smallest carbon footprint when compared to any other type of bottle stopper material.


Cork Properties:

Being environmentally friendly is a big plus in corks favour, but its usefulness comes directly from its properties. On paper, cork looks like a super material. Let's explore them.

  • Acoustic insulation - Cork has very low vibration conductance, making it good for decoupling and sonic insulation. 
  • Thermal Insulation  - The trapped air in the cork is in isolated bubbles which makes it a good thermal insulator.
  • Fire/Temperature resistant - It doesn't burn readily, when it does burn it does so without a flame and doesn't emit any harmful gasses. The lack of flame lowers the chances of it becoming an ignition source for other nearby materials.
  • Excellent mechanical properties - It has excellent elasticity and compressibility properties, which means it can be put under considerable stress without permanent alteration.
  • Light/Buoyant - Because of its high air content, cork weighs very little and floats.
  • Hypoallergenic - Cork does not absorb air particles from its surroundings, such as dust and pollen. This makes it a good material of choice for those with certain allergies.
  • Impermeable to liquids and gasses - The properties of the cell walls that make Cork resistant to both gasses and liquids also means that it ages well and without visible deterioration.
  • Resilient - Cork has excellent resistance to impact and abrasion.

Add to the list that cork is soft and pleasing to the touch, making it an ideal finish on items that will be handled. This brings us neatly onto potential uses... 


Potential uses for Cork:

Cork has so many things going for it that it is a must for any making environment. Cork is a waterproof material that is also surprisingly durable. It has good elastic and compression properties and excellent thermal, acoustic and anti-vibration resistance. These all combine to make it suitable for a wide range of uses.

As well as the obvious cork boards, some other possible uses include; coasters, mouse mats, heat/sound insulation, to decouple a project from a work surface, as a covering to improve the tactile nature of a product, gaskets, a protective layer or bumper, business card, and the list goes on and on. Cork can even be used as an alternative to leather. 


Cork Options Available From Kitronik:

At the time of writing, Kitronik stocks cork in sheet form.  We carry them in 1mm and 3mm, 600mm by 400mm sheets, plus one in a larger sheet size. We also offer sheets with adhesive backings, so no glue required!  They are; 


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