Angora and wool

The two fibres most often found in a thermal base layer are Merino as a thermal base layer and, for loft, angora. The companion fibre that sometimes appears in a blend is covered under Mohair explained, and the physics behind the whole system is set out in How thermal underwear works.

What angora wool actually is

Angora wool is a single, long staple of protein fibre that grows on the angora goat (Capra hircus angora), a breed first developed in Ankara, Turkey, in the late 1500s and later refined in South Africa and Australia. The fibre's 20 micron diameter is finer than a human hair at roughly 70 microns, yet each strand is hollow at the core, a medullated structure that locks air pockets in place and slows heat transfer from skin to the cold air outside. In a thermal underwear panel that hollow core does the work: a 200 g angora panel holds about 1.5 times the volume of trapped air that an equal-weight cotton panel holds, which is why a thin angora layer can feel as warm as a thick cotton one. The same structure that makes angora so light also makes it more fragile than merino, so in a base layer the angora is usually spun together with a stronger fibre to survive 100 or more machine washes at 30 degrees.

The angora rabbit question

The word angora also names the fibre of the angora rabbit, a 2.5 kg domestic breed whose hand-plucked fleece is even finer, around 12 microns, and is almost always sold as angora yarn for hand knitting rather than woven into a base layer. The rabbit's 3 seasonal molts yield about 200 g of raw fleece per animal per year, far less than the goat's 1 to 1.5 kg per shear, which is why rabbit angora commands a higher price per kilogram and appears in a thermal blend as a 10 to 20% accent rather than the main body. When a label simply says "angora" without specifying the animal, the thermal underwear context almost always means goat fibre, because rabbit angora is too soft and too expensive to carry the weight of a full panel.

How the fibre structure traps heat

The fibre structure traps heat through 3 stacked mechanisms, and understanding them explains why a blend out-performs either fibre alone. The first mechanism is loft: the crimp in a merino strand, which repeats every 5 to 8 mm along the fibre, forces the yarn to spring open and hold a column of still air against the skin. The second mechanism is the hollow core of angora, which multiplies the air volume inside each strand and adds a second insulating layer beneath the one the yarn holds. The third is the keratin protein itself, a fibrous protein that absorbs up to 30% of its own weight in moisture vapour without feeling wet, pulling heat-carrying water away from the skin and depositing it in the outer layers of the fabric where it evaporates into the night air. Merino does the wicking; angora does the insulating; together in a 60/40 merino/angora blend the panel stays dry at the skin and warm at the surface at the same time, which is exactly the job a base layer must do on a 0 to minus 5 degree evening walk.

Where angora comes from and how it is harvested

Where angora comes from and how it is harvested determines both the price on the label and the ethical record behind the garment. The angora goat is obtained through 2 main methods: shearing, in which a trained handler clips the fleece with electric shears every 8 to 12 months, and hand stripping, in which the handler pulls out the fibre that has naturally loosened from the coat. The goat's fleece grows 10 to 20 cm per year, so a 2-shear cycle yields roughly 2 kg of raw fleece per animal per year, which after carding, dehairing and spinning becomes about 500 g of clean angora yarn, a 75% waste ratio that is built into the price. A kilogram of raw angora fleece from a South African farm typically sells for 20 to 30 pounds, and after processing that same kilogram becomes 250 to 300 grams of finished yarn priced at 60 to 90 pounds per 100 g skein. Merino, by contrast, is sheared once a year from a sheep whose fleece yields 2 to 4 kg raw, and a kilogram of 18.5 micron merino fleece goes for 15 to 25 pounds, which is why a merino-heavy base layer costs less at the point of sale even though the garment uses more total fibre. The ethical record of the goat industry is cleaner than the rabbit industry's: goats are sheared, not plucked, and a well-run farm keeps the animal's coat short enough to prevent matting, a 10 minute procedure that replaces the 3 to 4 hour hand-plucking session a rabbit needs each molt. The word "cruel" that appears in search queries usually traces back to poorly sourced rabbit angora from the 1990s, when hand-plucking without waiting for the natural molt damaged the skin; the goat shearing method that dominates thermal underwear production has no such record.

Angora versus cashmere and merino in the same panel

Angora versus cashmere and merino in the same panel comes down to 3 measurable differences: diameter, loft and wicking speed. The table below puts the 3 natural fibres side by side on the properties that a base-layer buyer actually checks.

Cashmere wins on fineness at 14 to 19 microns and on loft per gram, but the cashmere goat sheds only 150 to 250 g of usable down per year, a fraction of the angora goat's output, which is why a 100% cashmere base layer costs 4 to 6 times more than an angora/merino one. Cashmere also wicks more slowly than merino, so in a sweat-heavy activity like a hill walk it can feel clammy at the chest while the angora/merino panel is already drying. Merino and angora in the same panel is therefore the default thermal underwear recipe: the merino handles the moisture, the angora handles the still air, and the 60/40 ratio keeps the garment under 30 pounds for a full mid-weight set, a price point that cashmere cannot reach at equal warmth.

Which fibre wins in which cold

Which fibre wins in which cold depends on the 2 conditions that change fastest: the ambient temperature and the sweat load on the skin. The angora-dominant panel wins when the air is still and the temperature sits between 0 and minus 5 degrees, the range where trapped air does most of the insulating and the wicking load is low. The merino-dominant panel wins when the activity raises the core temperature by 1 to 2 degrees, as on a brisk walk or a run in minus 10 degree air, because the merino's crimp and keratin absorb the moisture before it soaks the fabric and kills the loft. The 3 rules that cover most real-world choices are:

• Still air below 0 degrees: favour the angora at 50% or more of the blend for maximum loft
• Active movement above minus 5 degrees: favour the merino at 70% or more of the blend for wicking speed
• Wet conditions at any temperature: add a 10% mohair or cashmere accent to the blend to raise the moisture-absorption ceiling from 30% to 35% of fibre weight

The 30% moisture figure is not a hard limit; keratin absorbs more under sustained humidity, but past 30% the fibre begins to feel cool and heavy against the skin, which is the threshold a base-layer wearer notices first. An angora panel that has absorbed that 30% will feel 2 to 3 degrees colder at the surface than a dry merino panel of the same weight, so the wicking fibre is the one that keeps the warmth on a long walk. The 10 to 20 cm of fleece that grows on the goat each year is, in the end, the raw material that a mill spins, a knitter sets into a 200 g panel, and a wearer pulls on at 7 in the morning when the forecast says minus 3, and the 3 properties of loft, wicking and breathability decide whether that panel holds the heat through the 40 minute commute or lets it slip away by the second crossing.

Where to go next

FIBRESMerino as a thermal base layerWarmth and ItchFIBRESMohair explainedWhat Is Mohair Wool and How Warm Is ItGARMENTSHow thermal underwear worksHow Natural Fibres Trap Body Heat