Sunday, December 12, 2010

Fur, hair and wool - what's it all about?

A human hair
Photo done by Scanning Electron Microscopy (SEM)
© 2010 University of Minnesota Duluth
What's the difference between fur, wool and hair? This is a question that has been bugging me for a long time, so I tried to find out the answer. Let me tell you right up front that I didn't find a simple answer. The following is what I have gleamed but please post a comment if you can add any clarity to this question.
Some of this confusion seems to be a matter of word usage, as they are all the same protein (keratin), so technically they are all hair. However, some features that help distinguish the usage of terms: The thickness for example. Hair has lower density with 500 follicles/sq inch although not all are active at the same time, so let's say @100-200 follicles per sq inch should define hair. Sheep wool on the other hand, have up to 60,000 follicles/sq inch (Merino) and if the density is high, like a sea otter which has one of the highest densities at 800,000 per sq inch, the hair is referred to as fur. 
Another characteristic that some use to distinguish between terms is the growth pattern. Fur grows to a certain length then stops, while wool and hair keeps on growing. Although, this all depends on species and genetics, but generally this seems a good separator. Fur tends to have a major shedding time annually. Only the primitive sheep (eg. Soay, Orkney, Hebridean) and the so called 'hair' sheep breeds (eg.Saint Croix, West African, Wiltshire Horn) shed annually. 
Churro sheep wool. SEM
Photo by Dave Lewis and the Ohio 
 Agriculture Research and Development Center in Wooster
Wool tends to be the term for sheep fleece. Some sheep have kemp (thick hairs) in amongst the wool usually in is found in certain breeds of sheep and certain locations (eg. rear end), other sheep and Llamas have double coats with longer guard-type hairs designed to shed water and shorter insulating down fur (eg. Icelandic, Navajo Churro) for warmth.
Alpaca.
Photo by Dave Lewis and the Ohio 
 Agriculture Research and Development Center in Wooster
And then there is the more technical characteristics, like the cellular structure. The hair shaft is made of cuticle cells (keritine) that form scales, overlapping each other and pointing towards the tip. The cells form a protective coating around the cortex (inner area). In the fine merino wool, the cells are one layer thick while human hair can be 10 layers thick. This cellular structure is different for each type of hair (eg. eyelashes, whiskers, hair) from different animals. The scanning electron microscope photos here show some of the different structures. Look at the difference between human hair, churro sheep and angora rabbit in the pictures here. But, it doesn't help much in distinguishing hair from fur from wool.
Alpaca  Light microscope photo
showing the medulation (dark areas).
Photo by Dave Lewis and the Ohio 
 Agriculture Research and Development Center in Wooster
Inside the hair shaft is the cortex. This is the middle of the hair/wool/fur. If the centre of the cortex is hollow we call the core 'medulla' or a medulated hair. The inner core can be a consistently hollow core, or contain sections which are hollow. This medulation can provide insulation, hence hairs with no medulation hold heat less well than medulated hairs. Alpacas and Llamas have medulated hairs while sheep do not, hence Alpaca wool is a better insulator than wool.
Angora. Note the very interesting V-shape cell structure
SEM Photo by Dave Lewis and the Ohio
 Agriculture Research and Development Center in Wooster
So why is this interesting? For a few reasons. The structure of a fibre creates its characteristics for: heat retention; strength, elasticity, felting tendency, light reflection, etc. And also because I want to be able to analyze a fibre and have a way to figure out if it is Mountain Goat or sheep wool or from the Coast Salish wool dog.




10 comments:

  1. Nice job! Very useful for me.

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  2. could you make a table plsssss

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  3. I too struggle with this. Great analysis, article. Only one suggestion, keratin, not keritine.

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  4. Can you please reply me with how to cite your work posted here?
    Thanks a lot.

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  5. Icelandic sheep have a dual coat consisting of two true wool fibers. The outer coat (called tog) is not a guard hair, but rather a coarser wool than the undercoat (called thel). The tog is similar to the longwools.

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  6. from a utilitarian perspective, I am a spinner, wool is completely different from hair.
    a simple explanation is that wool has two characteristics that hair does not. wool has crimp and has the ability to create loft ( that soft squishy feel from yarn.) it also has the ability to felt. when you drag two wool fibers beside each other they have what is like little hooks on the outside of the shaft. These shafts will catch each other and cause the fibers to stick together. Rubbing these fibers together creates a material known as felt.
    Hair on the other hand will tangle together to create locks that can be combed out if desired. felted wool is there for life.
    hair does not have the ability to create a soft squishy type of single strand yarn. strands can be spun together to create a bit of loft but the individual strands are a strong tightly spun single.
    there are almost limitless differences in the processes of each that produce a different finished product.
    Wool is sensitive to heat and cold in that it opens the cuticles and then locks the fibers together with sudden change of temperature.
    I hope this adds some additional understanding of the differences.

    ReplyDelete
  7. from a utilitarian perspective, I am a spinner, wool is completely different from hair.
    a simple explanation is that wool has two characteristics that hair does not. wool has crimp and has the ability to create loft ( that soft squishy feel from yarn.) it also has the ability to felt. when you drag two wool fibers beside each other they have what is like little hooks on the outside of the shaft. These shafts will catch each other and cause the fibers to stick together. Rubbing these fibers together creates a material known as felt.
    Hair on the other hand will tangle together to create locks that can be combed out if desired. felted wool is there for life.
    hair does not have the ability to create a soft squishy type of single strand yarn. strands can be spun together to create a bit of loft but the individual strands are a strong tightly spun single.
    there are almost limitless differences in the processes of each that produce a different finished product.
    Wool is sensitive to heat and cold in that it opens the cuticles and then locks the fibers together with sudden change of temperature.
    I hope this adds some additional understanding of the differences.

    ReplyDelete
    Replies
    1. What about alpaca fibre? Not a wool! felts, spins nicely etc. Has guard hairs!!!Some say it is hair! The scales are on all fibre/hair. Some have more layers etc. Alpaca has lots of crimp! Yet again it is not wool! Angora spins great , yet not wool, and crimp?

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    2. As someone who has 'felted' hair or dreadlocks and felts with wool I assure you they all felt. In fact while learning how to spin we used dog 'fur' in the end it is all the same material with a few modifications to make it feel or behave slightly different depending on that mammals needs and genetics.

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  8. Oh... Sheep wool fibers aren't hollow? But where does wool's insulating abilities come from then?

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