Micron values

The Importance of Fiber Fineness for Yarns: Micron Values Under the Magnifying Glass

Why does some wool feel buttery soft, while other wool scratches the skin? A crucial factor is fiber fineness, which is specified in microns (µm).

The micron value describes the diameter of a single fiber, thus providing information about the softness, wearing comfort, and application area of a yarn. The finer the fiber, the more pleasant it generally feels on the skin.

For knitters and crocheters, this knowledge can be very helpful when choosing yarn. After all, a finished project should not only look beautiful but also be comfortable to wear.

 

What does the micron value mean for wool?

One micron (micrometer) corresponds to one thousandth of a millimeter. This unit is used to measure the thickness of individual wool fibers.

The rule of thumb is:

• under 18 microns = particularly soft
• 18 to 24 microns = comfortably wearable
• over 25 microns = robust and durable

The micron value alone does not determine the quality of a yarn, but it does give a good indication of its wearing properties.

 

Why are fine fibers softer?

The thinner a fiber is, the more easily it bends when it comes into contact with the skin. This creates a soft and pleasant feel.

Thicker fibers are stiffer and can irritate the skin more. This is often perceived as scratchiness.

That's why particularly fine fibers are suitable for:

• scarves
• shawls
• sweaters
• baby clothes
• hats

Stronger fibers are often used for:

• jackets
• slippers
• blankets
• outdoor clothing
• home accessories

 

Micron values of various wool fibers

 

Merino Wool: The popular all-rounder

Merino wool usually has micron values between 15 and 24 microns, depending on the quality.

Merino wool comes from merino sheep, originally from Spain, but now mainly bred in Australia, New Zealand, and South America. Particularly fine merino qualities feel soft on the skin and are excellent for garments worn directly.

Typical projects:

• Shawls
• Sweaters
• Baby clothes
• Hats

 

Cashmere: Luxury in its softest form

Cashmere is one of the finest natural fibers of all. The fibers usually range between 14 and 19 microns.

Cashmere comes from the cashmere goat, which lives in the icy heights of Mongolia, China, Iran, and Afghanistan. The yarn is lightweight, soft, and offers excellent thermal performance with low weight.

Typical projects:

• Scarves
• Shawls
• Sweaters
• Luxurious accessories

 

 

Alpaca

Typical micron value: approx. 18–30 microns

Alpaca is the noble fiber from South America and comes from the animals of the same name, which live in the Andes at over 3,000 meters above sea level. Alpaca wool has a special hollow fiber structure that makes it extremely light and heat-insulating. Alpaca is available in different qualities. Baby alpaca is significantly finer than regular alpaca. The fiber is known for its soft feel and excellent thermal properties. Another plus: alpaca contains no lanolin, which often makes it well-tolerated by people with wool allergies.

Typical uses:

• Sweaters
• Jackets
• Winter accessories

 

Vicuña

Typical micron value: approx. 10–13 microns

Vicuña wool, also known as the "Gold of the Andes." Vicuñas are wild relatives of alpacas and live in the Peruvian highlands at over 4,000 meters above sea level. They can only be shorn every two years, and a single animal yields just about 200g of wool. This makes vicuña wool an absolute rarity and explains why a scarf made of pure vicuña can easily cost over €1,000. Vicuña is considered one of the finest natural fibers in the world and is extremely lightweight and temperature-regulating.

 

 

Mohair

Typical micron value: approx. 23–38 microns

Mohair is obtained from the hair of the Angora goat. The breed originally comes from Turkey, but today it is bred in South Africa, the USA, and Australia, among other places. The fiber is characterized by its silky sheen, lightness, and high durability. Although mohair often has higher micron values than merino or cashmere, it is often perceived as pleasantly soft. This is due to the smooth surface of the fibers, which feels less coarse than many other types of wool. Mohair is often combined with other fibers and is particularly used for airy shawls, sweaters, and companion yarns. Characteristic is the slight fluff, which gives many knitting and crocheting projects a special look.

 

 

How is the micron value measured?

To understand how soft or robust a fiber truly is, its thickness must be precisely determined. But how do you measure something that is only a few micrometers thin? Various methods are used in specialized laboratories for this purpose.

Laser microscopy

The most precise method is laser microscopy. The fiber is placed under a high-resolution microscope and scanned with a laser beam. The computer then calculates the exact diameter of the fiber with an accuracy that can detect even the finest vicuña fiber. This method is extremely reliable but also expensive and complex.

 

Airflow measurement

Another technique is airflow measurement, also known as the Airflow method. Here, the fibers are placed in a chamber with a controlled airflow. Depending on how much the fibers impede the airflow, their thickness can be inferred. This method is particularly practical for the quick quality control of large quantities of wool, but not quite as precise as laser microscopy.

 

Light microscope

Probably the most traditional method is projection under a light microscope. The fiber is highly magnified and displayed on a screen, where a technician manually measures its thickness. While this method is simple and does not require high-tech equipment, it is more prone to errors as it heavily depends on the experience of the person doing the measuring.

 

So, the next time you stand in front of a yarn shelf or browse an online shop and stumble upon a micron value, you now know: this small number reveals more than meets the eye.

Of course, the micron value alone does not determine whether a yarn feels pleasant. Processing, spinning method, and personal preferences also play an important role. Nevertheless, it can be a helpful guide and sometimes even decide whether a project becomes an absolute favorite piece or leads a life at the back of the closet.

Because let's be honest: after hours of stitches, rows, and sewn-in ends, no one wants to find out that the finished scarf, while beautiful, feels like a loving hug from sandpaper.