What Is Merino Wool
Merino wool is not ordinary wool. It comes from a specific breed of sheep — the Merino — selectively bred over centuries to produce fibres that are finer, softer, and more technically capable than any other wool variety. It is the most versatile natural fibre in menswear and womenswear: warm without bulk, breathable without being cool, odour-resistant without any synthetic treatment.
This guide explains exactly what makes merino special, what micron count means and why it matters, how Gran Sasso sets the benchmark for merino knitwear, and how to care for merino so it lasts for decades.
1 | What Is Merino Wool?
Merino wool comes from the Merino sheep — a breed originally developed in Spain and now raised primarily in Australia, New Zealand, and South America. The Merino breed has been selectively developed for thousands of years to produce exceptionally fine, long-staple wool fibres.
What distinguishes merino from standard wool is fineness. A standard wool fibre measures 30–40 microns in diameter. Superfine merino typically measures 15–19 microns — finer than a strand of human hair, which averages 70 microns. This extreme fineness is the source of merino's softness: fibres this fine cannot produce the bristle sensation that makes coarser wool feel scratchy against skin.
Merino at a Glance
- Breed: Merino sheep, raised primarily in Australia, New Zealand, South America
- Fibre diameter: 15–24 microns (standard wool: 30–40 microns)
- Fibre length: long-staple — reduces pilling tendency
- Natural properties: thermoregulating, odour-resistant, moisture-wicking, biodegradable
- Benchmark producers: Zegna Baruffa (Italy), Loro Piana (Italy), The Woolmark Company (certified)
2 | The Key Properties of Merino Wool
Merino wool's properties are not marketing language — they are the result of its specific fibre structure, which differs fundamentally from synthetic fibres and from coarser wools.
Thermoregulation
Merino fibres have a naturally crimped structure that traps air. In the cold, this trapped air insulates. When warm, the same structure releases moisture as vapour, creating a cooling effect. This is why merino works across a wider temperature range than almost any synthetic alternative.
Odour Resistance
Merino fibre has a naturally antimicrobial lanolin coating and a complex protein structure that binds odour molecules rather than releasing them. A merino knitwear can be worn multiple times between washes without developing the persistent odour that synthetic fabrics accumulate quickly.
Moisture Management
Merino can absorb up to 35% of its own weight in moisture without feeling wet or clammy. The fibre wicks moisture away from the skin and releases it as vapour from the outer surface — keeping you drier during activity than cotton or most synthetics.
Breathability
The natural structure of the merino fibre allows air movement through the fabric. This prevents the overheating and stuffiness associated with tightly woven synthetics, making merino comfortable across a wider range of temperatures and activity levels.
Softness Against Skin
Below 19 microns, fibres flex on contact with skin rather than irritating it. This is why superfine merino can be worn directly against the body by people who find standard wool unbearable. The finer the micron count, the softer the feel.
Biodegradability
Merino is a natural protein fibre — it biodegrades fully at end of life. This is in contrast to synthetic fibres, which persist in the environment for decades. A merino garment worn for 20 years and composted at end of life has a fundamentally different environmental profile to fast-fashion synthetics.
3 | Micron Count Explained
Micron count (µm) is the measurement of individual fibre diameter. It is the single most important technical specification in merino wool — finer microns mean softer handle, greater loft, and improved drape.
| Grade | Micron Count | Typical Use | Feel |
|---|---|---|---|
| Ultrafine Merino | Under 15µm | Luxury knitwear, next-to-skin base layers | Cashmere-level softness |
| Superfine Merino | 15–18.5µm | Premium knitwear, fine-gauge sweaters | Exceptionally soft, no itch |
| Fine Merino | 18.6–20µm | Mid-weight knitwear, cardigans | Soft, skin-friendly |
| Medium Merino | 20.1–23µm | Outer knitwear, heavier sweaters | Comfortable, occasional sensitivity |
| Broad Merino / Strong Wool | 23µm+ | Outerwear, rugged knitwear | May be scratchy for sensitive skin |
The Practical Takeaway
If a brand does not state the micron count, assume it is 20µm or above. Premium knitwear houses publish their micron specification precisely — and at OD's we can tell you the specification of the Gran Sasso pieces we stock. Generally, anything 18.5µm and under is exceptional quality.
4 | Gran Sasso — The Merino Benchmark at OD's
Gran Sasso was founded in Pescara, Italy in 1952. Over seventy years of continuous operation, they have become one of Italy's most respected knitwear houses — making everything in their Pescara factory using yarns sourced from Zegna Baruffa and Loro Piana, two of the world's preeminent spinning houses.
The reason Gran Sasso is the benchmark for merino knitwear at OD's is not simply the raw material — it is the combination of superfine or extra-fine merino yarn with high-gauge Italian construction. Where mass-market knitwear uses coarser yarn on lower-gauge machines, Gran Sasso invests in finer yarn and more complex knitting to produce a fabric with superior drape, handle, and longevity.
What Makes Gran Sasso Different
- Made entirely in Pescara, Italy — not outsourced
- Yarn sourced from Zegna Baruffa and Loro Piana spinning houses
- Superfine and extra-fine merino — 16–18µm range across main knitwear line
- High-gauge construction — finer stitch density, superior drape
- Long-staple yarn — reduces pilling tendency
- Washes well — knit structure retains shape over years of careful washing
Browse Gran Sasso at OD's
View the full Gran Sasso collection in store at 44 Barrow Street, St Helens, or online at OD's Designer Clothing.
5 | How to Care for Merino Wool
Merino is more robust than its softness implies — but it does have specific requirements. The key enemies are heat (causes shrinkage and felting) and biological detergents (enzymes attack the protein fibre structure).
Washing
- Hand wash or machine wash on a wool/delicate cycle — 30°C or cooler. Many merino pieces are machine washable on a gentle cycle; check the care label.
- Use a wool-specific detergent — such as Woolite or Eucalan. Avoid biological detergents — the enzymes are designed to break down protein stains and will gradually damage wool fibres.
- Turn inside out before washing — protects the visible surface from friction during the wash cycle.
- Do not agitate or wring — merino fibres felt (irreversibly mat together) when subjected to heat, friction, and moisture simultaneously. Handle gently when wet.
Drying
- Lay flat to dry — never hang a wet merino garment. The weight of the wet fabric stretches the knit vertically, distorting the shape permanently. Lay on a clean dry towel and reshape gently to the original dimensions.
- Never tumble dry — heat causes merino to shrink and felt. Even a low-heat tumble dryer cycle can cause permanent and irreversible shrinkage.
- Dry away from direct heat — do not place merino on a radiator. Dry at room temperature.
Storage
- Fold, do not hang — hanging a knitwear on a hanger stretches the shoulders and distorts the knit over time. Fold and store in a drawer or on a shelf.
- Store clean — moths are attracted to food stains and body oils on fabric. Always wash or air a merino piece before storing it for the season.
6 | Protecting Merino from Moths
Moths are the principal threat to a merino knitwear collection. It is not the adult moths that cause damage — it is their larvae, which feed on keratin, the protein found in wool, cashmere, and other natural fibres. A single moth infestation can destroy expensive knitwear before you are aware there is a problem.
Cedar
Cedar blocks, balls, or hangers release natural oils that moths dislike. Place cedar blocks in drawers and wardrobes where knitwear is stored. Replace or refresh annually — the scent fades as the oils evaporate. Sand lightly with fine sandpaper to restore the scent.
Lavender
Dried lavender sachets work on the same principle — the scent deters moths naturally. Place sachets in drawers and replace annually. Lavender sachets are a practical and pleasant-smelling alternative to mothballs.
Sealed Storage
For long-term storage (off-season), store merino knitwear in sealed ziplock bags or vacuum storage bags after washing. Moths cannot reach fabric they cannot access.
Regular Inspection
Check stored knitwear every few months. Early detection of moth damage — typically small irregular holes — allows action before a full infestation. If you find evidence of moths, launder all affected items immediately and treat the storage area.
Mothballs Work — But Avoid Them
Traditional mothballs (naphthalene or paradichlorobenzene) are highly effective but toxic — harmful to humans and pets, and they leave a persistent chemical smell that can be very difficult to remove from fabric. Cedar and lavender are safer alternatives for all but the most serious infestations.
Shop Merino Wool at OD's
Every piece below is in stock at OD's Designer Clothing — authorised UK stockist.