What’s micron got to do with it?

We’ve written about GSM and what has it got to do with t-shirts before. But did you know there is another, equally important aspect to pay attention to when buying anything made of merino - or any other wool, for that matter?

Micron sounds something straight out of a physics lesson. Micron - or a micrometre - is a unit of measure in the metric system equal to 1 millionth of a meter in length (or about 39 millionths of an inch, to our customers using the imperial system). In the wool business, a micron is the measurement used to express the diameter of the wool fibre, which is the most important characteristic for determining the wool value. The lower the micron value, the finer the wool fibre.

A typical, high-quality merino wool garment will use merino wool at a diameter of 17.5-18.5 microns - that’s less than 2.6 times the width of human hair! The smallest recognisable size to the naked eye is around ~55-75 micrometres. Amazing, we know. A small micron value also means that merino wool feels much softer and smoother next to your skin, compared to other types of wool. Cashmere fibres boast 19 microns whereas wool will usually start feeling itchy above 22 microns. That’s why some of those woolly socks and sweaters knitted by gran sometimes feel a bit prickly, despite all the love that has gone into making them.


However, while a typical merino fibre is 17.5 microns, a merino sheep doesn’t prance around as a little fluffy fleece cloud as usually a merino fleece contains a combination of fibres, some as low as 10 microns in diameter, others more than 25 microns - all depends on the age and health of the sheep. Finer the fibre, finer the yarn, finer the fabric. Result? Clothes that keep you warm (or cool, because that’s another awesome quality of merino but more about that some other time) yet are stylish and classy.

You may think that if something is as fine, it surely must be fragile too? Some manufacturers suggest using a nylon core or a nylon wrap to increase the strength of the fabric when using a 17.5 micron merino fibre but this means that the fibre isn’t 100% organic any longer. The beauty of merino is precisely the fact that it’s fine, soft and durable on its own. We asked the same question from one of our fabric suppliers, worried about the durability of the 17.5 micron fibre and received a beautiful answer:

“When one looks at each individual fibre, then a 17.5 micron fibre has a lower tensile strength than that of a 18.5 micron. It is thinner so that’s logical. However, when tested in the lab the same yarn made with 17.5 micron and 18.5 micron will have similar results, in particular, tensile strength. That’s because there are more 17.5 micron fibres in a similar piece of fabric than of that of made of 18.5 micron ones. Think of the yarn as a tube. You can fill the tube with sand or pebbles. In both cases, the tube remains the same diameter but there are more particles in the one filled with sand.”

We use only pure 100% merino wool and make sure that all our suppliers use fibres no larger than 19.5 microns in their yarns as we don’t want no itchy-skratchy skin around here, no sir. You can check the micron measure of all our clothes in the product description (example here).

What’s micron got to do with it blog picture