Understanding Fibre Microns: What Makes Merino Soft (and Why It Matters)

Why Some Wool Is Scratchy (And Some Isn't)

"I can't wear wool—it's too itchy."

We hear this all the time. And it's based on real experience—many people have worn uncomfortable, scratchy wool sweaters.

But here's the secret: itchiness isn't about wool—it's about microns.

Understanding micron count is the key to finding incredibly soft, comfortable wool you'll want to wear every day.

What Is a Micron?

A micron is a unit of measurement: one millionth of a metre.

In textiles, "micron" refers to the diameter (thickness) of individual fibres.

The rule:

• Lower microns = finer, softer fibres
• Higher microns = thicker, coarser fibres

That's it. The entire difference between scratchy wool and luxuriously soft wool comes down to fibre thickness.

The Micron Scale: From Coarse to Ultra-Fine

Human Hair (for reference): 70-100 microns

Natural Fibres:

40+ Microns:

• Coarse wool (traditional "scratchy" wool)
• Carpet wool
• Upholstery
• Feel: Rough, prickly, uncomfortable against skin

30-40 Microns:

• Standard wool (what cheap sweaters are made from)
• Shetland wool
• Some lambswool
• Feel: Somewhat itchy, tolerable over clothing but not comfortable against bare skin

25-30 Microns:

• Medium-grade wool
• Some merino blends
• Lambswool
• Feel: Less scratchy, acceptable for some people, but still noticeable texture

20-25 Microns:

• Fine wool
• Standard merino wool
• Feel: Soft, comfortable, minimal scratchiness

17-20 Microns:

• Superfine merino wool
• High-quality merino
• Feel: Very soft, luxurious, comfortable against bare skin

15-17 Microns:

• Ultra-fine merino
• Cashmere (14-19 microns)
• Feel: Incredibly soft, indistinguishable from cashmere to most people

11-16 Microns:

• Angora rabbit (11-16)
• Qiviut (musk ox, ~13 microns—rarest and softest)
• Feel: Cloud-like, extremely delicate

Why Micron Count Matters for Comfort

The science of scratchiness:

When wool fibres are thick (high micron count):

• They're stiff enough to poke through fabric
• They bend against your skin, causing irritation
• Your nerve endings register them as "prickly"

When wool fibres are fine (low micron count):

• They're too flexible to poke through
• They bend completely against skin without resistance
• Your nerve endings register them as "soft"

Threshold for most people: ~25 microns

• Below 25 microns: Comfortable
• Above 25 microns: Itchy

Below 20 microns: Luxuriously soft (no one finds this itchy)

Merino Wool: The Goldilocks of Natural Fibres

Merino sheep produce the finest wool of any sheep breed.

Merino micron ranges:

• Strong Merino: 23-24 microns (still soft, but on the edge)
• Medium Merino: 20-22 microns (comfortably soft)
• Fine Merino: 18-19 microns (very soft)
• Superfine Merino: 15-17 microns (as soft as cashmere)
• Ultrafine Merino: <15 microns (extremely rare, incredibly soft)

Why merino is perfect:

• Soft enough to wear directly against skin (under 20 microns)
• Durable enough for everyday wear (stronger than cashmere)
• More affordable than cashmere
• Versatile performance properties (breathable, odour-resistant, temperature-regulating)

At Sashū, we use fine to superfine merino (15-19 microns) for ultimate softness without sacrificing durability.

Cashmere: The Luxury Standard

Cashmere comes from the undercoat of cashmere goats.

Cashmere micron range: 14-19 microns (similar to finest merino)

Why cashmere feels so soft:

• Ultra-fine fibres (14-16 microns is most common)
• Longer staple length (individual fibres are longer, creating smoother feel)
• Natural crimp (creates loft and softness)

The trade-off:

• More delicate (finer fibres = more fragile)
• Pills more easily (especially low-quality cashmere)
• More expensive

Cashmere under 15 microns is incredibly rare and extremely expensive.

The "Prickle Factor": Why Some People Are More Sensitive

Everyone has different sensitivity thresholds:

Not Sensitive:

• Can comfortably wear 25-30 micron wool
• Traditional wool sweaters feel fine

Moderately Sensitive:

• Needs 20-23 microns to feel comfortable
• Regular merino works well

Highly Sensitive:

• Needs under 19 microns
• Superfine merino or cashmere only

If you've always thought you "can't wear wool," you probably just need finer microns.

How to Tell Micron Count When Shopping

Unfortunately, most brands don't list micron counts.

What to look for:

Label Language:

• "Superfine merino" = 15-17 microns
• "Fine merino" = 18-19 microns
• "Merino wool" (no descriptor) = 19-23 microns (still soft, but not superfine)
• "Wool" or "lambswool" = 25-30+ microns (may be scratchy)

Price Indicator:

• Ultra-fine merino or cashmere: $250-400+ for sweater
• Fine merino: $150-300
• Standard merino: $80-150
• Generic wool: $30-80

Generally, finer microns cost more (harder to produce, more labour-intensive).

Feel Test:

• If you can touch the fabric, rub it against sensitive skin (inner wrist or neck)
• Scratchy = high microns
• Soft = low microns

Microns and Durability: The Trade-Off

Finer isn't always better for every purpose.

Ultra-fine fibres (under 16 microns):

• ✅ Incredibly soft
• ✅ Luxurious feel
• ❌ More delicate
• ❌ Pills more easily
• ❌ Less durable for heavy-duty use

Fine to superfine fibres (17-20 microns):

• ✅ Very soft
• ✅ Comfortable
• ✅ Durable enough for everyday wear
• The sweet spot for most people

Medium fibres (20-24 microns):

• ✅ Soft (for most people)
• ✅ Very durable
• ✅ Great for activewear, socks, base layers
• ❌ May be slightly scratchy for sensitive individuals

Coarse fibres (25+ microns):

• ✅ Extremely durable
• ✅ Great for outerwear, rugs, heavy-duty items
• ❌ Uncomfortable against bare skin

For everyday sweaters and clothing: 17-20 microns is ideal (soft but durable).

Other Fibres and Their Microns

Alpaca: 18-25 microns

• Softer than sheep's wool (comparable to fine merino)
• Hypoallergenic (no lanolin)
• Slightly less elastic than merino

Cashmere: 14-19 microns

• Softer than most merino
• More delicate
• Higher price

Mohair: 25-45 microns

• Thicker than merino (but feels soft due to smoothness)
• Lustrous and durable
• Slightly itchy for some

Qiviut (Musk Ox): ~13 microns

• Softer than cashmere
• Extremely rare and expensive ($300-600/oz)
• Warmer than any other fibre

Silk: 10-13 microns

• Ultra-fine (softest natural fibre)
• Not insulating like wool
• Different properties (smooth vs. crimped)

Cotton: 12-20 microns (but feels different due to structure)

• Plant fibre (smooth, not crimped like wool)
• Less warm than wool
• Different comfort properties

Why Superfine Merino Is the Best Value

Comparing cost-per-micron:

Cashmere (15 microns):

• $400 sweater
• ~$27 per micron of softness

Superfine Merino (17 microns):

• $250 sweater
• ~$15 per micron of softness
• Nearly as soft, half the price

Plus merino advantages:

• More durable than cashmere
• Better performance properties (odour resistance, moisture-wicking)
• Easier care

For most people, superfine merino (17-19 microns) offers the best balance of softness, performance, durability, and value.

How Microns Affect Other Properties

Micron count doesn't just affect softness—it influences:

Warmth:

• Finer fibres trap more air
• More air pockets = better insulation
• Cashmere (14-19 microns) is warmer than coarse wool (30+ microns) by weight

Breathability:

• Fine fibres create tighter weave
• Better moisture management
• More comfortable across temperature ranges

Durability:

• Thicker fibres (20-24 microns) are stronger
• Ultra-fine fibres (under 16 microns) are more fragile
• 17-20 microns is the sweet spot (soft + durable)

Pilling:

• Ultra-fine fibres pill more (they break more easily)
• Medium fibres (19-22 microns) pill less
• Proper fabric construction matters more than microns for pilling

Shopping Smart: Questions to Ask

When buying merino or wool:

1. "What's the micron count?"
   • If they don't know, it's probably 23+ (standard merino or coarser)
2. "Is this superfine or fine merino?"
   • Superfine = 15-17 microns
   • Fine = 18-19 microns
3. "Can I feel it against my skin?"
   • Test on inner wrist or neck (most sensitive areas)
4. "What's the price per garment?"
   • Under $100 = unlikely to be fine merino
   • $150-300 = likely fine merino
   • $300+ = likely superfine merino or cashmere

Sashū's Micron Standards

At Sashū, we use:

• Fine to superfine merino (15-19 microns) for our sweaters and tops
• Premium cashmere (15-17 microns) for our cashmere collection

Why?

• Soft enough for even sensitive skin
• Durable enough for decades of wear
• Beautiful drape and feel
• Professional quality

We believe in transparency—if you have questions about the micron count of any piece, ask us.

The Bottom Line

If you've avoided wool because you think it's scratchy:

• You've probably only experienced high-micron (25-30+) wool
• Fine merino (18-20 microns) feels completely different
• Superfine merino (15-17 microns) rivals cashmere

Micron count is the secret to soft wool.

Try superfine or fine merino—your perception of wool will change completely.

Explore our fine merino collection and discover how soft wool can be.

Not scratchy. Not itchy. Just incredibly comfortable natural fibre clothing.