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  • Brief history

  • Structure

  • Evaluation on the alpaca

  • Care and preparation

fleece outline.jpg

Alpaca Fleece

Brief History

South American camelids consist of two wild varieties, the guanaco and the vicuna, and two domestic types, the llama and the alpaca.  Vicuna fleece with a fiber diameter of 13-14 microns (one micron is 1/25,000 inch; human hair is about 60-90 microns) is one of the finest and most costly fibers in the world.

Alpacas were domesticated from vicunas about 6000 years ago.  An impressive feat:  the vicuna comes in one color and produces about a pound of fleece every other year; alpacas deliver annual weights of 2-5 pounds of prime blanket fleece in shades of white, tan, brown, black, and gray, plus pinto and other patterns.

Spaniards in the sixteenth century killed many of the llamas and alpacas, displaced them from all but the high mountain country, and disrupted the criadores' breeding systems.  
Subsequent attempts to maximize fleece weights and inter-breeding between llamas and alpacas coarsened the alpacas' fleece.  Judging from mummified alpacas, the pre-conquest animals produced fiber of under 22 microns; most of Peru's present day fiber is over 25 microns.  However, the genetics to produce that fine fleece is still within the animals; with careful breeding, we are producing it again.

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True guard hair is stiff, straight,
and highly medullated (hollow)
fiber that is much longer than the fleece it protects.

Guard hair keeps the softer
underlying fiber from being
damaged by grass, twigs, leaves,
shrubs, etc when the animals are
grazing.

You'll find guard hair on the lower chest (because the animal pushes forward with the chest when it moves) and in the armpits and belly (where  it next encounters brush, grass, etc or accumulates it when lying down).

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Structure

When we talk about alpaca fiber, we mean the fiber grown from secondary hair 
follicles which surround a primary follicle
(the uncrimped and coarser or larger diameter fibers,
which we often refer to as "guard hair").  

The more secondary follicles there are, the denser the

fleece - that is, the more fiber the alpaca is producing.
As density increases, presumably the fleece will be finer since more

fibers are crowded into the same area. The "guard hair" seems to disappear; in fact, the primary fibers are getting finer and behaving more like secondary fibers.

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fiber compare.jpg

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Two breeds of alpaca with distinctly different fleece.

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  Suri  

GiovanniHd2.jpg
ChampHd1.jpg

Huacaya

LollipopFlc.jpg

Please don't reproduce these photos without permission.

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Each fiber is encircled by a layer of tiny cuticle cells, or scales, which overlap each other in an irregular pattern.  (This is the reason fleece can be spun into yarn; scales from individual fibers cling together.)  

The scale edges stick up and out from the fiber - .04 microns high for huacaya alpaca, compared to .08 for wool.  

This means that, given a wool fleece and an alpaca fleece of the same average diameter, the alpaca will feel finer and less scratchy because the fibers are smoother.

Interior cells, the cortex, give the fiber strength and elasticity.  Fine fibers are composed of a high proportion of cortex.  The huacaya cortex is made up of orthocortex and paracortex growing next to each other along the length of the fiber, with the paracortex on the insideof any wave or crimp. The crimp is what makes the fiber elastic and gives it "memory" - that is, when stretched, then released, it returns to its original length.

Suri fibers have a unilateral cortex, fewer and much flatter scales, and less medullation, making them smoother to the touch and more lustrous, but a little more slippery to spin.

Running up the interior of the cortex are hollow areas - medulla - more in coarser fiber, less in finer.  Alpaca (and cashmere) have smaller amounts of medullation than do other fibers.  
Medullated fibers are stiff, with pointed tips that migrate toward the outside of yarn (desirable in Harris Tweed, but increasing the itchy feel of a fabric); they reflect light and take dye differently from more solid fibers.

When we were first learning about alpacas, we were often told that the hollow fibers provided the warmth of an alpaca garment.  But what actually makes you feel warm is the air trapped between fibers, and finer fibers provide more spaces to hold more air.

 

On the other hand... I don't remember where I got this, but it makes sense.

Fiber Medullated.jpg

Evaluation of fleece on the alpaca - uniformity, crimp, density, fineness, handle

This is the fun part - putting your hands into that lovely fleece.

But first, stand back and take a look at the alpaca.  You want to see fleece that looks uniform; no area should stand out.  

With the sun behind the alpaca, look for a "halo" of straight fibers protruding from the fleece; these are undesirable coarser uncrimped hairs.

Up close, you can see them as a straight tip at the end of the lock.  All alpacas have them, especially in the apron (the lower chest area) and belly, but a better quality animal will have fewer in the blanket and neck, and its apron will start lower on its chest.  However, crias' secondary fibers are still developing; they often have a prominent "halo" that disappears after their first shearing.
                                                                                                            
Use your hands to open and spread the fleece.  Looking at a huacaya, check the lock structure.  It may be tight with many short waves per inch (high frequency, low amplitude) or bold with tall but fewer waves. The fibers may be bundled into thick or thinner locks.  
Some alpacas, like vicunas, have no apparent crimp, but each fiber shaft has a wave or "crinkle." These fleeces can be very fine, but are probably not dense.
The frequency and amplitude of the crimp is designated as curvature, measured as degrees per millimeter of the fiber length. Suri has low curvature of 10-35; huacaya measures 25-60.
There are some studies showing that high curvature fleeces are finer and some that show only limited correlation.
In my opinion (you'll find others who disagree), the type of crimp (the wave along a lock of fiber) is a matter of personal preference.

Only a skin biopsy is accurate to measure density, but you can get a rough idea.  If you put the flat of your hand against the alpaca's side, does the fleece resist your pressure?  When the fleece is opened, how much skin do you see?  More skin visible means less density - that is, there are fewer fibers per area of skin.  Density, along with length, is important because we sell our fleeces based on weight (although the price may be based on fineness).  But many breeders feel that fineness and density are opposing traits, and a finer fleece will weigh less.

"Handle" refers to how the fleece feels when you take it in your hand or gently rub it between your fingers.  You would like to describe it as soft and smooth rather than stiff or rough. Remember that alpacas like to roll, and a coating of dust can make a fleece feel much coarser.

Suri fibers are straight so they have no crimp.  There are different styles of suri locks - flat, wavy, twisted, and so on - but if suris are sheared every year, as they should be, the lock structure can be hard to evaluate.  
I prefer to concentrate on luster; that shine is what draws me to suris, along with the silky smooth handle.  Beware, the right lighting can enhance a mediocre luster, and a cloudy day makes it hard to evaluate.

We always want to know the "micron count."  This is an actual measure of fineness - of the average diameter of each fiber (AFD).  
The standard deviation (SD) is another average: it tells us the average that individual fibers differ from the AFD of the sample.  A SD of 5 would mean that the greatest percentage of fibers range from 5 microns below to 5 microns above the average. A low SD tells you that the fleece is very uniform and will therefore have a soft handle.
The coefficient of variation (CV) is used as a measure of consistency; it is the SD divided by
the AFD.

It's reassuring to have what seems like a nice solid number to look at and use for comparisons.  We say, "His CV is 22%; he's very consistent.  His micron is 22; he's very fine."  But there are a few pitfalls here. The first is that usually we're talking about a single sample of fleece, 2 inches by 2 inches. It's a pretty good stand-in, but it's also a pretty small proportion by which to judge the entire fleece, especially regarding uniformity.  
Pitfall #2 is that alpacas' fleeces usually coarsen as they get older.  If one breeder is sending in fiber samples at 12 months and another at 24 months, they can't be compared. In fact, it's tricky to compare animals from different farms, since their environment has been
different.
Pitfall #3 is the CV, which is merely a ratio, SD divided by AFD.  Two alpacas, one with a SD of 3 and another with a SD of 6, can have the same CV, yet no one examining the actual animals would ever judge those two fleeces as equally uniform.

I confess, I do use the CV in marketing.  Our stud, Ceazar, had a CV of 15%, a very impressive number.  I expect that people who know something about micron counts will like that number; people who know a little more will see that his AFD is also low and will deduce that his SD is therefore also low.