01How merino wool is made
Merino sheep are shorn, usually once a year. The raw fleece is greasy, so it is graded by fiber diameter and length, then scoured to remove lanolin, dirt and plant matter. The clean wool is carded and combed into "tops", a rope of parallel fibers, and spun into yarn.
For apparel, the yarn is knitted into jersey or rib for base layers and tees, or flat knitted into sweaters. Many mills treat the wool so it can go in a washing machine without felting, typically with a chlorine-based or chlorine-free shrink-resist process. If machine washability matters, ask which treatment is used.
Pure merino is soft but not very strong at light weights, so a lot of performance merino is blended with nylon, either mixed in or as a core inside the yarn, or with spandex for stretch.
02Micron grades
Fiber diameter, measured in microns, is the single biggest factor in how soft merino feels and what it costs. Coarser fibers are what make wool itch. Naming varies by market, but this is the general picture.
| Grade | Approximate microns | Typical use |
|---|---|---|
| Ultrafine | About 15.5 and under | Luxury next-to-skin and fine suiting |
| Superfine | About 15.5 to 18.5 | Base layers, tees, fine knitwear |
| Fine | About 18.5 to 20 | Base layers, socks, sweaters |
| Medium | About 20 to 23 | Sweaters, outer layers, socks |
03Mulesing, RWS and animal welfare
Mulesing is a practice, mostly in Australia, of removing strips of skin around a sheep’s tail area to reduce flystrike. It is widely criticized, and many brands now require mulesing-free wool.
The Responsible Wool Standard (RWS) certifies farms on animal welfare and land management and does not allow mulesing. It is a chain-of-custody standard, so every step from farm to finished product has to be certified for you to make an RWS claim. Other options include ZQ certified wool and suppliers who sign a non-mulesed declaration.
04Pros and cons
- Regulates temperature: warm in cold, comfortable in mild heat
- Resists odor, so base layers and tees can be worn more between washes
- Absorbs moisture vapor and stays warm when damp
- Fine microns feel soft against skin with little or no itch
- Natural, renewable and biodegradable fiber
- Expensive compared with synthetics and cotton
- Light pure merino gets holes and pills; needs blends or careful care
- Shrinks and felts in hot water unless treated
- Slower to dry than polyester
- Animal welfare questions; you need mulesing-free or certified supply to make claims
05Typical uses and price
- Base layers and thermals
- Hiking and running socks
- Merino t-shirts and travel wear
- Fine gauge sweaters and cardigans
- Beanies and neck gaiters
- Suiting and tailoring (woven)
Price tier: Premium. Merino costs well above cotton and synthetics, and finer microns cost more. Certified mulesing-free or RWS wool adds a further premium. Nylon-core or polyester blends lower the cost and add durability.
06How to spec it with a factory
Merino quotes swing on micron, blend and certification. Put all three in the tech pack, or two mills will quote two different fibers.
| No. | Field | What to write |
|---|---|---|
| 01 | Fabric composition | Exact percentages, e.g. 100% merino, or 87% merino 13% nylon, or merino with a nylon core |
| 02 | Micron | Average fiber diameter with a maximum, e.g. 17.5 to 18.5 micron |
| 03 | Construction | Jersey, rib, interlock, or flat knit gauge for sweaters |
| 04 | Weight | GSM after finishing (e.g. 150, 200, 250), with a tolerance |
| 05 | Treatment | Machine-washable shrink-resist treatment, and whether chlorine-free |
| 06 | Sourcing | Mulesing-free required; RWS or ZQ certified if you want to claim it |
| 07 | Shrinkage | Maximum after machine wash, length and width, with test method |
| 08 | Pilling | Minimum pilling grade and test method |
Certifications and marks
- Responsible Wool Standard (RWS)
- Animal welfare and land management, no mulesing. Every step in the chain must be certified to make a claim.
- Mulesing-free declaration
- At minimum, get the wool supplier to declare the fiber is non-mulesed, with traceability to origin.
- Woolmark
- Woolmark licensing lets you use the Woolmark logo on products that meet its fiber content and quality tests.
- OEKO-TEX Standard 100
- Tests the finished fabric for harmful substances, useful for next-to-skin base layers.
From the factory floor
- Ask for a fiber test report showing average micron. Coarser wool is the easiest substitution to hide in a quote.
- Machine wash test samples on the care label setting. Untreated merino will shrink badly.
- For light tees and base layers, consider a nylon-core yarn to cut holes and returns.
- RWS claims need certified suppliers all the way to your garment factory; ask for transaction certificates.
07Merino wool vs regular wool
Regular wool from other breeds is usually coarser, often 25 microns and up, which is why it itches. Merino is finer and softer, so it works next to skin. Coarser wool is cheaper and tougher and suits outerwear, rugs and heavy sweaters.
08Merino vs cashmere
Cashmere comes from goats, not sheep, and is typically around 14 to 19 microns. It feels softer and loftier but is weaker and more expensive. Merino is more durable, easier to wash and better for active base layers.
09Merino vs polyester base layers
| Merino | Polyester | |
|---|---|---|
| Odor | Resists odor well | Holds odor unless treated |
| Dry time | Slower | Fast |
| Warmth when wet | Stays warm | Less warm |
| Durability | Lower at light weights | High |
| Cost | Premium | Budget to mid |
10FAQ
Q01Does merino wool itch?
Fine merino, around 18.5 microns and under, rarely feels itchy to most people. Coarser merino and regular wool are more likely to itch.
Q02What micron merino is best for base layers?
Most next-to-skin base layers use roughly 16.5 to 19.5 micron merino. Finer is softer but less durable.
Q03Can you machine wash merino wool?
Only if it has been treated to resist shrinking. Untreated merino should be hand washed or washed on a cool wool cycle and dried flat.
Q04What is mulesing?
Mulesing is removing strips of skin from around a sheep’s breech to prevent flystrike, practiced mainly in Australia. Mulesing-free and RWS certified wool avoid it.
Q05Why is merino wool expensive?
Fine merino fiber costs much more than cotton or synthetics, it needs careful processing and treatment, and finer microns and certified supply cost more again.