To attach the label ‘natural’ to a material is perhaps a little misleading, as it could be argued that everything we use derives from a natural material. Therefore, in order to understand what is meant when people use this term we need to put it into some kind of context.
In a world where natural resources, such as oil, gas and various ores are being rapidly depleted, where scientists tell us our carbon emissions are too high and the waste we create can no longer simply be buried, we need to find alternatives to the use of energy intensive, non-renewable, polluting materials. This is the context in which we can start to arbitrarily attach the label ‘natural’.
In general terms ‘natural materials’ in their raw state exhibit a range of properties that make them an obvious choice for a particular function. Using our context above, this will automatically mean that in addition to its eventual in use attributes, its processing and end of life disposal will have been given equal consideration.
This does not necessarily mean that the material requires no processing or modifications, merely that these are within acceptable parameters.
Time for an example:
These days most of us are very familiar with insulation materials, so this seems like a good area to consider.
For many years now the majority of builders and homeowners have been insulating buildings with either mineral wool or, more recently, rigid foam or polystyrene board.
The origin of each of these products is in minerals that have been created over geological timescales. Once depleted, these will not be available to us again.
To turn each of these minerals into our desired end product requires vast amounts of energy that fundamentally alters the base properties of the original material.
If we take Rockwool as an example, I doubt there are many of us who have ever picked up a rock and thought ‘I bet this would make a great insulation material’! Yet, in our previously energy-rich world, full of quarrying and mining companies, that’s exactly what did happen. Somebody decided that melting down rock at an extremely high temperature (1600°C) before eventually processing it into light, layered, aerated matting was a good use of rapidly diminishing natural resources.
Each of the other mineral based insulation materials has to undergo a similar type of high intensity processing in order to make it fit for purpose and each one, whilst fulfilling its intended function perfectly well, cannot be easily disposed of at the end of its use.
The reason we describe 100% British sheep’s wool as a natural material is that with minimal processing, shearing, basic scouring (washing) and felting it provides us with a material that regulates heat and humidity, provides efficient acoustic absorption, puts useful nutrients back into the soil, is 100% renewable, is relatively non-polluting and is 100% biodegradable.
So for us a natural material is one that is renewable (often a crop) that requires minimal energy and/or chemicals to turn it into the end product, is non-polluting in use and can be responsibly disposed of at the end of its life with no detrimental effect to the natural environment.
We wish to stress that the text in this section was not written with the intention of making comparisons in performance between different materials. Its purpose is merely to try and explain what we mean when we use the term ‘natural materials’