Special note on acrylics
IMPORTANT UPDATE!

We use a lot of things made from petrol (basically, plastics) and they are probably all much better ideas than actually burning it for fuel!  Rather than the processing of acrylic yarns, it's really the oil industry itself that's the bigger problem,  with spillages still regularly occurring, not to mention proxy wars and the disastrous environmental effects of burning fossil fuels. 

The acrylic knitting yarns we use are not manufactured in the UK but are spun under license to the familiar brands, mainly in Far East, Turkey, India, Mexico, and South America.

Unlike some imports to the rag trade, they are made in industrialised countries, in modern factories with environmental regulations.  However the production of acrylics is basically a chemical industry and is bound to produce pollutants, and doubtless they are much more harmful to the environment than growing plant fibres:

"For synthetics, a crucial fact is that the fibers are made from fossil fuels.   Very high amounts of energy are used in extracting the oil from the ground as well as in the production of the polymers.

"A study done by the Stockholm Environment Institute on behalf of the BioRegional Development Group  concludes that the energy used (and therefore the CO2 emitted) to create 1 ton of spun fiber is much higher for synthetics than for hemp or cotton:


KG of CO2 emissions per ton of spun fiber:

crop             cultivation   
fiber                production        
TOTAL
polyester USA 0.00 9.52 9.52
cotton, conventional, USA 4.20 1.70 5.90
hemp, conventional 1.90 2.15 4.05
cotton, organic, India 2.00 1.80 3.80
cotton, organic, USA 0.90 1.45 2.35

(see http://oecotextiles.wordpress.com/2011/01/19/estimating-the-carbon-footprint-of-a-fabric/)

And a study done for the New Zealand Merino Wool Association shows how much less total energy is required for the production of natural fibers than synthetics:

Embodied Energy used in production of various fibers (MJ/kg):

Jute fibre cultivation (excluding field labour, retting and decortication)

3.75-8.02

 Wet decortication (sisal and henequen)

2.0

 Flax fibre non-woven mat

9.6

 Woollen and worsted: spinning and winding frames

10.8-12.8

 Woollen and worsted: spinning (ring frame)

18.7-28.6

 Wool (NZ merino on-farm energy use)

 14.8-53.4

 Wool (NZ merino dry top landed in China)

48.1-76.6

 Viscose

169

SOURCE:  “LCA: New Zealand Merino Wool Total Energy Use”, Barber and Pellow,      http://www.tech.plym.ac.uk/sme/mats324/mats324A9%20NFETE.htm

Because wool is an organic substance it is less harmful environmentally than petrochemical products, but it is  more harmful than plant based textiles, which is what we would expect.  However the figures above refer to wool fibre itself and do not include the chemicals used for defatting, chemical cleaning and bleaching of the wool before dying and spinning, processes which are not necessary for synthetically spun fibres. Taking this into account would alter the figures above.

Also to be considered is the fact that conventionally grown cotton and its processing has an extremely high carbon footprint and pollution rating.  It is a crop which is grown on a huge scale and uses massive amounts of water and chemical fertiliser.  I have read that the production of denim, for instance, is the most ecologically damaging of all textiles. This is a clear case where organic is superior to conventional.

It would be impossible here to detail the quantity and variety of greenhouse gases and other pollutants from the textile industry.  Suffice it to say that it is huge and that the textile industry is one of the world's biggest pollluters. 

The most ecologically sound way forward for conscientious knitters would be to use plant fibres, or yarn which we have personally recycled from old garments, or yarn purchased second hand.  If we buy recycled yarn we should realise that reclaimed fibres involve an energy intensive process.  Having looked, or should I say just glimpsed, into all this, I am now personally determined to use plant fibres or my own recycled yarns. 

Having said all this, and returning to the issue of acrylics manufacture ... aside from localised pollution, and in terms of greenhouse emissions, the manufacture of acrylics is not nearly as harmful to the environment as transport, for instance, which in turn is not as harmful as animal husbandry. This astonishing fact has been widely debated since the United Nations Food and Agriculture Organisation published its now famous report Livestock's Long Shadow in 2006.
http://www.europarl.europa.eu/climatechange/doc/FAO%20report%20executive%20summary.pdf
Though of course using such an argument is always a cop-out from the subject in hand!

IMPORTANT UPDATE

Alarmingly, it has come to light recently (early in 2018) from experiments done at the University of Plymouth, that acrylic and other petrol-derived fibres are contributing to the micro plastic residues in the sea and inland waters. In the domestic setting the microfibres are removed from garments during washing, then released into the sewage system. In this case they are filtered out effectively in the sewage works, but then the sewage residue ends up on the land, with effects which haven't yet been discovered (did you know that even teabags are sealed with plastic polymers which survive composting? Gardeners have noticed this!) However, scientists in the industry say that 'synthetics are manufactured to perform as we need them to' and are keen to develop artificial fibres which will be more stable over the years. They also point out that farming animals for wool fibre has a massive carbon footpring that should be balanced against the impact of acrylics. (BBC Radio 4 'Costing the Earth').

However, as far as sheepless knitting goes, let's hope that the spinning of plant fibres will continue to be improved and that they will become more widely available as knitting yarn. Meanwhile, if you choose acrylics, choose the more expensive ones or those spun with more stable fibres such as cotton, nylon or lycra. Those which are smoothest are those most likely to be stable when washed. This photo shows a very good example of a silky smooth yet soft acrylic, which you can see has a very special label - the first yarn label in the UK to use the V word!
vegan label
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