Histogram | Read and understand a fiber analysis

Reading the histogram is a must to know much better the quality of the alpaca that is evaluated. Although the histogram does not say everything, is not infallible and presents only an idea of the quality of the fleece of the whole animal (it remains a sample!), it is a tool of choice to compare several alpacas between them and get a better idea of what it will become... this is how we improve the qualities of a herd; By selecting our progenitors with care, not otherwise!

Histogram | Lab Analysis Sheet
OFDA 100 Analysis sheet of a sample.

A single histogram certainly gives very interesting information about an animal, but several histograms over several years allow to better know the evolution of this said animal.

At the end of the day, several analyses give us a more logical choice! I explain why besides it makes more sense at the end of this article with an example, but at first glance, here in detail the information that the analysis of the laboratory provides...

You don't understand all the concepts at first glance? You find this article arid and difficult to read?

Don't get discouraged, it's normal! It is an apprenticeship like so many others that takes time, logic and a lot of concentration at the beginning, a thousand milles from the artistic side of the fiber. But as for skate, we end up getting there!

The Constitution of the histogram

Histogram-Example written
A histogram with the different data, here framed.

In the preamble, this is what the summary of a histogram looks like everywhere; A bunch of numbers, symbols and letters.

Although the presentation differs sometimes, it is practically always in this order that we see the different data of the histogram (which I have separated here in red squares). According to the test performed, the curvature (here: curv for curvature) is not always present and other data may also be present or not, including the spin fineness, which is the fineness touch (which is also computable with the data Main).

The 4 main data are usually always: AFD, SD, CV and >30.


AFD (average fiber diameter) is one of the main data of the histogram, the average fibre diameter of the sample analyzed. This is calculated in Micron (1 micron = 0.001 mm). On average, for alpaca, this figure between 15 and 35 microns.

The smaller the number, the better, since the finesse of the fiber is intimately linked to the softness.

The softness associated with the micron accounts for about 70 to 80% of the total value attributed to fibre 1. That is, the more a fleece is fine (and softer!) The more expensive it can be on the market!

For reference, know that a red blood cell is about 8 microns and that a human hair is located between 50-100 microns. The vicuna (wild ancestor of the still alive Alpaca) and high quality silk have about 12 and 10 microns in diameter. Some alpacas have started to reach in the United States the 10 microns mesure, although it is still very rare.

For a fiber from 21 microns, it may start to have some reactions but at 25 microns, the average people will begin to feel slight itching on the skin if the item is worn in sensitive areas of the body, like the neck.

Each person have a different sensibility; the effect can vary from one person to another, from one region to another on their body and from one circumstance to another (if it is too hot, for example, the itching can be accentuated).

At 30 microns, fibre is considered as strong as a guard hair; You'll see further that the proportion of hairs above 30 microns is also recorded in the histogram for the sample analyzed. So finesse has an impact on what we're going to do with the fiber.

It should be noted that the scale on the alpaca fibre is much less perceptible to the touch than the sheep ones; This makes the alpaca fiber 25 microns softer to the touch than wool for an identical analysis. This peculiarity makes that wearing alpaca is more enjoyable and disturbs less some people with more sensitive skin.


The SD (standard deviation) represents the variability of the fibre diameter around the average data (AFD), in microns.

We figure to still the closest to 1 possible; so that the fibres are the most uniform in the sample. Uniformity improves the quality of products designed, of course, but also the sensation of general softness to the touch and the tensile strength of the fiber 2 and animals with low SD generally exhibit less variability in microns in the entire fleece (not just in the sample). In an average fibre population, 66% of the measured fibres were in the first SD of the average (one micron before the average and the other after), 95% in a total of 2 SD and 99% in 2.6 SD 3.

The SD is a difficult data to use for comparing several alpacas that do not necessarily have the same micron since the SD tends to increase with AFD. That is why many people often use the CV for the comparison between animals. Nevertheless, this data is increasingly being demanded by commercial buyers; It is foolish not to worry about it and it gives leads that the CV can not give on the fiber.


The CV is a combined data of AFD and SD and is presented as a percentage. To obtain the CV without having it, it can be calculated simply as follows:

(SD/AFD) x 100 = CV

The average fibre distribution usually gives a CV of 24%. It is best to have the lowest CV possible for a better uniformity of fiber and a CV always below 24%. At each slice of an average of 5% below 24%, there is an improvement of about 1 micron to the touch (softness to touch is the data of the spin fineness, which is found on the analysis sheet of the laboratory, but not always recorded in The broadcast histogram).

To be precise (hum!) ...

Histogram: fineness Spin formula
In the formula opposite, the MFD is the same data as AFD and CVD% is the CV.



The Spin fineness is a good measure to use to compare the finesse of alpacas between them, precisely because they understand the data of the CV and AFD.

If we take the example above with the simple calculation: AFD 18.5 SD 3.3 CV 18.0% >30 0.6% CURV 55.2
A CV of 18% (24%-18% = 6) is therefore equivalent to a little more than one micron less for this animal to touch, thus about 17.3 microns.


This percentage is equivalent to what the sample contains in fibres that are above 30 microns. It is of course hoped that this figure is as low as possible even if the best animals still have a few guard hairs in their fleece. A too high percentage will affect the softness and comfort associated with the fiber, but also the profitability of the fleece.


The Curvature is a data that is not always present in the histogram, but I like to see more and more. It gives as information the degree of the curve to each wave in the fiber (crimp) in millimetre. Despite what some people think, the crimp is not only a criterion of personal appreciation, but a very interesting data for the improvement of the quality of the fiber since once spun, this curvature will change not only the volume of the thread (so that it is well spongy to the touch!) , its memory (its ability to regain its shape), but also its heat coefficient. Generally speaking, especially for alpaca since it tends to have a much less pronounced curvature compared to other quality fibers, the higher the degree of curvature, the more positive it is!

It should be known however that the higher this figure is and less generally the fibre will have length (but will be more elastic on the other hand). An alpaca that has a nice length and a high degree of curvature; It's heaven! 🙂

Histogram comparison

That's when it gets fun and interesting! Because once we know how to read the analyses (and that the headaches associated with comprehension are gone!), animals can be compared more easily. Even if we don't have all the information about animals, these histograms can influence our real interest in an animal or help us choose between two very similar animals. It must be noted, of course, the age that the animal had during the histogram; Because comparing animals that are not the same age, we obviously compare apples and oranges!

Animal #1, 1 year: AFD 19.6 SD 3.7 CV 19.0% >30 1.3%, CURV 41.0

Animal #2, 1 year: AFD 20.7 SD 4.9 CV 23.8% >30 2.4%

Here, for example, we notice that the first animal has a better finesse (AFD) than the second one of about 1 micron. If we look at the CV, we notice 5 percent down 24% for the 1st animal which gives it about 1 micron of extra softness to the touch for a total of 2 microns softer than the 2nd animal.

The number of guard hairs for the first animal is also less than the second.

Several histograms are better than one!

A single histogram says a lot about fiber for a very specific time. On the other hand, nothing better than comparing several histograms of the same animal since it shows us the evolution of the fleece over several years, so also an idea of how this one will evolve in the future.

So here I am doing a personal analysis of two animals... an example will convince you!

Animal #1

1 year: AFD 19.6 SD 3.7 CV 19.0% >30 1.3%, CURV 41.0
2 years: AFD 20.9 SD 3.5 CV 16.9% >30 1.3%, CURV 44.9
3 years: AFD 25.1 SD 4.0 CV 15.8% >30 6.4%, CURV 40.7
4 years: AFD 23.1 SD 3.9 CV 16.9% >30 3.3%, CURV 39.3

Animal #2

1 year: AFD 20.7 SD 4.9 CV 23.8% >30 2.4%
2 years: AFD 20.2 SD 4.3 CV 21.5% >30 2.0%
3 years: AFD 22.8 SD 5.2 CV 22.9% >30 6.3%
4 years: AFD 24.9 SD 4.9 CV 19.8% >30 11.8%

Here you find the same 2 animals that we evaluated previously. On the other hand, in this case, with several histograms, we can make a much interesting analysis. For example, as of the second year, we notice that the fleece of the second animal has almost no change. With regard to the second fleece of the first animal, its AFD (micron) increased by 1.3 point. We could, rapidely, think that the second animal is better because it has been able to retain its finesse, but before any easy deduction, it is necessary to observe the CV which has changed also... For the first animal, in reality, softness to touch is about 1.5 points lower than AFD (CV24%-16.9% = 7.1/5 = 1.42 micron less), thus 19.5 microns while it changes only from 0.5 micron for the second animal (19.7 microns).

The first animal is therefore, again in my opinion, in its second year, the most interesting from the point of view of the histogram, even if the average finesse has moved a little more than that of the second animal.

In the third year, we notice a drastic change of the first animal with a AFD of 25.1 microns and a CV of 15.8%. He always has a touch of about 23 microns just like the second animal because of his CV. Normally, note the abrupt changes in the histogram; If it was the last available histogram of the first animal, one might think of a Blow outin its 3rd year (a rapid change in fiber quality), but the 4th histogram confirms that this is not the case since the micron decreases again at the age of 4 years and the micron difference is always about 1 micron per year. It should be noted that an overweight can cause the diameter of the animal's fibre to rise by several microns; This is the case.

It is noticed that at the age of 4, the 2nd animal remains till the 1st despite a normal evolution of its fibre. The second animal's fur was developed much faster than that of the first animal, which was still at 3.3% at 4 years, compared with 11.8% for the second animal.

On average, there is an increase of about 2 microns to the maximum between the 1st and 2nd year and a micron per year thereafter although there are exceptions. Animals that do not increase with the years (and even whose finesse is accentuated!), it exists, but it is very rare!

As for the CV in general on these two animals, the first animal seems to have a better uniformity of micron in its sample, which means that it might be the case in its fleece also... which is sum all doubly interesting saw the beautiful progression of fineness that we analyzed!

The histogram is not infallible

Yes, even though the histogram is a very convenient way to compare two animals to each other, there are a lot of traps that must be avoided and take the results for what they are...

1. Do not buy only by using a histogram

Even if they are very practical, they do not give any information about the health of the animal, the state of its teeth, the paws, the hooves... etc. Fiber density and length are also a very important part of evaluating an animal's fiber and the histograms do not give this information. Do not forget that a histogram remains only one tool among many others...

2. Skinny or fat, your alpaca?

The animal's flesh condition has a lot of impact on the histogram.

An animal that is too skinny will have a particularly great histogram (low micron) but does not necessarily give you a healthy animal. And once its healthy weight resumed, the histogram shows the true face of the animal... with perhaps some additional physical problems created by this time period when the animal did not have what it needed in nutrients...

An animal too fat will have a histogram often several microns higher compared to what it may have; Knowing that the animal is overweight can help since the comparison is not the same as if its state of flesh was correct!

We want to evaluate what the animal has intrinsically as quality, not what it actually has on its histogram at all costs... it is necessary to make a bias sometimes to certain collected data !

3. The histogram, it's cheating too...

Some methods of calculation by laboratories can be circumvented when you know exactly when "an alpaca must to fast"... Yes, I know, you can raise your eyes to heaven; It's horrible to read this... Do breeders really do that? It remains to be seen...

There are different machines to test the fiber and the most used are the Laserscan and the OFDA 100. For analysis, these machines require a sample of less than 2 mm length of the fiber that is cut in the sample that the breeder has sent... at a precise distance... which also corresponds to a very precise moment of the growth of the fiber.

This measure hardly corresponds to a few weeks of life in a year and that is why we know that theoretically, analysis can be faked...

Unlike these machines, the OFDA 2000 gives a ratio based on the whole length of the fiber sent, thus on all the growth of the fiber. On the other hand, few breeders use these machines.

I will probably write in an another article the differences between the different scientific tests possible (histograms, density...) ... there is a lot to say!


  1. A Definitive Guide to Alpaca fiber, Cameron Holt.
  2. http://www.aaft.com.au/guide.html
  3. http://www.alpacas.com/AlpacaLibrary/Html/FiberTesting.htm

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