Understanding Alpaca Fleece

Alpacas are fiber-producing livestock.

That sounds obvious, but understanding what makes one fleece different from another can become complicated very quickly. Micron, density, staple length, uniformity, crimp, brightness, histograms, EPDs, skin biopsies - there’s an entire vocabulary surrounding the fiber alpacas grow.

The good news is that you don’t have to become a fiber scientist to understand the basics. And one of the most important things to learn is this:

No single measurement defines a great fleece.

A useful, high-quality fleece brings multiple characteristics together, and the importance of each can change depending on the animal, its age, the intended end use, and your breeding goals.

First: Fiber vs. Fleece

The terms are often used interchangeably, but they aren’t exactly the same.

Fiber refers to the individual strands an alpaca grows.

Fleece generally refers to the coat collectively, particularly once it has been shorn from the alpaca.

At shearing, the highest-quality portion of the fleece is generally the blanket, which comes from the main body of the alpaca. Fiber from other areas may be separated into seconds and thirds because those areas often contain greater variation in length, fineness, and coarse fibers.

None of that necessarily makes the fiber unusable. It may simply make it better suited to a different purpose.

Huacaya and Suri Fleece

There are two breeds of alpaca, and their fleece grows differently.

Huacaya fiber grows with loft and usually displays organized staple formation and crimp.

Suri fiber grows in locks that hang closer to the body and is particularly prized for its luster, drape, and lock structure.

The vocabulary changes somewhat between them - brightness and crimp are commonly discussed with Huacaya, while luster and lock structure are particularly important in Suri - but many of the fundamentals are shared.

AOA evaluates characteristics including fineness, density, uniformity, staple length, fleece weight, absence of undesirable coarse fiber, and fleece soundness in both breeds. 

Fineness: Understanding Micron

This is probably the fleece measurement most alpaca owners hear first. A micron is a unit used to measure fiber diameter. One micron is one-millionth of a meter.

When someone says an alpaca has an 18-micron fleece, they’re talking about the approximate diameter of those fibers. Generally, a lower micron means a finer fiber.

Finer fibers usually feel softer against the skin and can be desirable for next-to-skin garments. AOA’s current U.S. Alpaca Fiber Standard uses numerical grades ranging from Grade 0 at 15.0–16.9 microns through Grade 6 at 32.0–34.9 microns. Importantly, AOA deliberately avoids terms such as “baby,” “royal baby,” and “superfine” in its standard because those names are not used consistently throughout the fiber industry. 

But here’s where people sometimes get too focused on a single number: Finer doesn’t automatically mean better.

An extremely fine fleece with poor length, little density, considerable variation, weak fiber, or undesirable coarse fibers may be less useful than a slightly higher-micron fleece that performs well across those characteristics.

Micron is important. It just isn’t the whole story.

Uniformity: How Similar Are the Fibers?

Imagine two fleeces that both average 20 microns. One contains mostly fibers clustered very close to 20 microns. The other contains a mixture of very fine fibers and much coarser ones that happen to average out to 20. Those fleeces may have the same average micron - but they can feel and process very differently.

That’s why we care about uniformity. Uniformity can refer to consistency in fiber diameter, staple length, density, structure, and other characteristics both within the blanket and from one area of the fleece to another.

On a fiber test you’ll commonly see:

• SD - Standard Deviation
  This tells us how widely the individual fiber diameters vary around the average. Generally, a lower SD indicates greater uniformity.
• CV - Coefficient of Variation
  CV expresses that variation as a percentage of the average fiber diameter, allowing another way to compare uniformity.

AOA’s U.S. fiber standard identifies an average fiber-diameter standard deviation of 3 microns or less as a benchmark for uniformity.  For us, uniformity is an especially important breeding consideration because we’re not simply trying to produce fine fiber. We’re trying to produce consistently good fiber.

Staple Length: How Much Did the Alpaca Grow?

Staple length is the length of the fiber from near the skin to the tip. Longer isn’t automatically better in every situation, but adequate growth matters tremendously for both fleece production and processing.

It is also important to consider how long the fleece has been growing. Six inches of fiber produced over two years tells a very different story from six inches produced in one.

That’s why judges and breeders often evaluate staple length relative to the animal’s growth period. AOA considers longer staple length relative to growth period a positive fleece characteristic.  Length also needs to be reasonably uniform.

AOA’s current U.S. fiber standard identifies processable Huacaya fiber as generally falling between 2 and 5.5 inches and Suri fiber between 2 and 7.5 inches, with consistent length across the blanket important for processing. 

Density: More Than Looking Fluffy

Density is essentially how much fiber an alpaca is producing within a given area of skin. A fluffy-looking alpaca isn’t necessarily a dense alpaca.

True density involves the number and organization of fibers growing from the skin. Greater density can contribute to greater fleece weight and can also help protect the fleece from dirt and weathering. 

Density can be evaluated in several ways. Experienced breeders and judges evaluate it physically on the animal. Fleece weight provides another piece of the picture. Some breeders also use skin biopsies, which can measure follicle density and characteristics of primary and secondary follicles.

Research has demonstrated relationships between follicle density and fleece characteristics, although a biopsy is still a measurement from a specific sample location rather than a magical score defining the entire alpaca. 

Like everything else on this page: It’s another tool.

Crimp, Character & Staple Structure

Open a Huacaya fleece and you’ll usually see some form of wave running through the fibers. That’s crimp. But simply having lots of visible crimp isn’t the goal.

AOA describes crimp as the natural wave formed as fibers grow and organize within staple groups. Crimp can vary in frequency and amplitude, and it is influenced by things including fineness, density, and uniformity. Character describes the regularity and evenness of that crimp throughout the staple and fleece. 

In practical terms, we want to see organized fiber. Good staple formation. Consistency. Definition that continues through the fleece rather than disappearing when you move a few inches across the animal.

Suri fleece is evaluated differently, with emphasis on lock structure and formation rather than Huacaya-style crimp.  

Brightness & Luster

This may be one of the easiest fleece qualities to appreciate. Brightness describes the way Huacaya fiber reflects light. Luster describes the distinctive sheen of Suri fiber.

And brightness does not mean white. A black, brown, fawn, grey, or spotted alpaca can have beautifully bright fleece.

When you open a high-quality fleece and it seems to almost reflect light back at you, that’s the characteristic breeders are describing.

Handle: What Does the Fleece Actually Feel Like?

Sometimes numbers tell us a lot. Sometimes you put your hand into a fleece and immediately notice something. Handle is the tactile feel of the fiber.

Softness isn’t determined by average micron alone. Uniformity plays an important role too, which is why two fleeces with similar average fiber diameters may feel noticeably different.

AOA specifically describes handle as an indication of both fineness and micron uniformity.  It’s one reason we don’t want to breed from spreadsheets alone. The alpaca still needs to be evaluated. The fleece still needs to be opened. And sometimes your hands tell you something the first number on a report doesn’t.

Guard Hair, Medullation & Comfort

Not every fiber within a fleece is identical. Coarser fibers - particularly those associated with guard hair - can affect how fleece processes and how comfortable a finished product feels against the skin.

AOA identifies guard hair as undesirable for fine-fiber processing because these coarse fibers behave differently during spinning and dyeing and can contribute to the “prickle” sensation in finished products. 

This is where two common fiber-test measurements come into play:

• Fibers >30 microns tells you what percentage of the tested fibers exceed 30 microns.
• Comfort Factor is essentially the reverse — the percentage measuring 30 microns or less. 

Another measurement you may encounter is medullation. A medullated fiber contains a central core or medulla. The amount, type, and diameter of medullated fibers can influence processing characteristics, dye uptake, softness, and the presence of undesirable coarse fiber.

Again, the goal isn’t merely chasing one perfect number. We’re looking at how all the pieces work together.

Reading an Alpaca Fiber Histogram

Send a fleece sample to a fiber-testing laboratory and you’ll receive what can initially look like a sheet of alphabet soup.

A typical report may include:

• MFD or AFD — Mean/Average Fiber Diameter
• SD — Standard Deviation of fiber diameter
• CV — Coefficient of Variation
• SF — Spin Fineness
• % >30 — Percentage of fibers over 30 microns
• CF — Comfort Factor
• Curvature — a measurement related to fiber curvature/crimp
• Staple Length
• Medullation, when measured

The histogram itself shows the distribution of fibers across different diameters rather than giving you only an average.  That distinction matters. An average tells us where the middle falls. The shape of the distribution helps show us how the fleece arrived at that average. And that can be much more informative.

A Histogram Is a Snapshot

There’s one more important limitation. A fleece test describes the fiber that was sampled from that animal, at that age, at that point in time.

Age, nutrition, health, pregnancy, environmental conditions, and other factors can influence fiber production.

AOA’s current nutrition education specifically notes that nutrition can affect fiber production and quality, while also acknowledging that some relationships remain more complicated than the simple rules sometimes repeated within the industry. 

That is why repeated testing can be more informative than looking at one result in isolation. We’re interested not only in how fine an alpaca was as a juvenile, but also: How does that fleece hold as the animal matures?

Histograms and EPDs Are Not the Same Thing

This is another area that can become confusing. A histogram describes the fleece sample from an individual alpaca. An EPD - Expected Progeny Difference - is a genetic prediction.

AOA’s EPD program uses performance information from the animal and genetically related animals to estimate the contribution that animal is expected to make to its offspring for measurable traits. 

That means an alpaca’s personal fleece test and its EPDs answer different questions.

A histogram might help answer: What did this alpaca produce?

An EPD helps answer: What might this alpaca genetically contribute to the next generation?

Both can be useful. Neither should be confused with the other.

So What Makes a Great Fleece? There isn’t one perfect formula. For us, we’re looking for balance. We want fineness without sacrificing production. Density with length. Uniformity within the staple and across the animal. Strong fleece structure. Brightness. Soft handle. Low levels of undesirable coarse fiber. And, perhaps most importantly for a breeding program, we want those qualities to continue through generations. A beautiful juvenile fleece is exciting. A line of animals maintaining and reproducing desirable fleece characteristics is something more.

More Than One Measure

We use fleece shows, hands-on evaluation, histograms, pedigrees, production records, EPDs, and - in some animals - additional tools such as skin biopsy information.

None of them gets to make the breeding decision alone. A remarkable histogram doesn’t correct poor conformation. A high density number doesn’t erase lack of uniformity. A championship doesn’t guarantee an animal will reproduce itself. And the lowest micron in the barn isn’t automatically the alpaca we should breed.

The value comes from learning what each tool measures, understanding what it doesn’t measure, and putting those pieces together. That’s how data becomes useful instead of just impressive.

From Fleece to Finished Products

Ultimately, all of these measurements lead back to the reason alpacas grow fleece in the first place: to be used.

Different fleece characteristics lend themselves to different applications. Fine, uniform fiber may be wonderful for garments worn against the skin. Other fiber can become hats, outerwear, rugs, felt, dryer balls, craft projects, or countless other products.

A fleece doesn’t have to be the finest fleece on the farm to have value. It needs to find the right purpose.

That’s something we especially enjoy seeing through Elderwood’s annual Shear-and-Share, where fiber artists can select the alpaca - and the fleece - they want to work with.

Because the story of alpaca fleece shouldn’t end at shearing. That’s where the next one begins.