Everything You Need to Know About Cotton

Is cotton the best fabric for t-shirts?

For everyday wear, cotton is hard to beat. It's soft, breathable, easy to wash and comfortable against the skin, which is why it's been the default t-shirt fabric for generations. But "best" depends on what you're doing in it. For long days outdoors, physical work or changeable weather, cotton has real limits, and that's where merino wool earns its place.

Here's what you need to know to choose well.

What is cotton?

Cotton is a natural plant fibre. It grows as a fluffy boll around the seeds of the cotton plant, a shrub grown in warm climates such as India, China, the United States and Brazil. The fibre is almost pure cellulose, the same material that gives plants their structure.

After harvest, the cotton is ginned to separate the fibres from the seeds. The fibres are then cleaned, carded (brushed into alignment) and, for finer fabrics, combed to remove short fibres. They're spun into yarn, then either knitted (for t-shirts) or woven (for shirts and trousers) into fabric.

Is 100% cotton the best t-shirt fabric?

For casual, everyday wear, 100% cotton is an excellent choice. It feels soft, lets air circulate, is gentle on sensitive skin and holds up well to regular washing.

Where it falls short is moisture. Cotton absorbs sweat and rain readily but dries slowly, and once wet it feels heavy and cold. It can also shrink and lose shape over time.

So the honest answer: cotton is the best fabric for many t-shirts, but not for every situation. For relaxed days, around town or layered under a jacket, cotton works well. For active or outdoor use, a performance fibre like merino wool is the better choice.

What are the benefits of cotton?

• Softness: Cotton fibres are naturally smooth, and they get softer with washing.
• Breathability: Cotton knits allow air to move through the fabric, keeping you comfortable in mild, dry conditions.
• Gentle on skin: Cotton rarely causes irritation, making it a good option for people with sensitive skin.
• Easy care: Most cotton is machine washable, tolerates warm water and doesn't need special detergents.
• Durability: Good quality cotton, particularly heavier weights, stands up well to years of regular wear and washing.
• Versatility: It takes dye well, comes in many weights and weaves, and suits everything from lightweight tees to heavy work shirts.

What are the downsides of cotton?

• Moisture retention: Cotton absorbs a lot of moisture and holds it close to the skin rather than moving it away.
• Slow drying: Once wet, cotton can take hours to dry, especially in cool or damp conditions.
• Loss of warmth when wet: Wet cotton loses most of its insulating ability, which can chill you quickly outdoors.
• Shrinkage: Cotton that hasn't been pre-shrunk can shrink noticeably in its first few washes, particularly with hot water or a hot dryer.
• Loses shape: Cotton knits can stretch out at the neck, hem and elbows, and wrinkle easily.
• Holds odour: Cotton doesn't resist odour the way wool does, so it needs washing after most wears.

What is the difference between cotton types?

"Cotton" covers many fabrics. The difference comes down to how the yarn is knitted or woven and how the fabric is finished.

• Jersey: A lightweight knit fabric with some natural stretch. This is the classic t-shirt fabric: soft, drapey and comfortable.
• Oxford: A woven fabric with a slightly textured basketweave. It's durable and a little heavier, used for button-down shirts that look sharp but handle everyday wear.
• Poplin: A tightly woven, smooth and lightweight fabric with a crisp finish. It's common in dress shirts and warm-weather shirts.
• Flannel: A woven fabric brushed to raise a soft, fuzzy surface. The brushed fibres trap air, making flannel warmer than other cottons, which is why it's a cool-weather staple.
• Brushed cotton: Any cotton (knit or woven) that has been brushed on one or both sides for extra softness and a little added warmth.

Quick guide: choose jersey for t-shirts, Oxford or poplin for shirts, and flannel or brushed cotton when you want extra warmth.

Does cotton shrink?

Yes. Untreated cotton commonly shrinks around 3 to 5%, and sometimes more, mostly in the first few washes. Knits such as jersey tend to shrink more than tightly woven fabrics.

Why it happens: During manufacturing, cotton yarns and fabric are pulled under tension. Heat, water and agitation in the wash let those fibres relax back to their natural length, so the garment tightens up.

How to avoid it:

• Look for pre-shrunk cotton, which has been treated to reduce shrinkage, usually to a small percentage (all Swanndri t-shirts use pre-shrunk fabric).
• Wash in cold or warm water rather than hot.
• Skip the dryer, or use a low heat setting.
• Dry flat or on a line, and reshape the garment gently while it's damp.

How do you wash and care for cotton?

Good care keeps cotton looking better for longer and reduces shrinkage and fading.

• Temperature: Wash at 30 to 40°C for everyday cotton. Cold water is gentlest on colour and fit.
• Turn it inside out: This protects the outer surface and any prints from abrasion.
• Wash with like colours: Dark cotton can bleed, especially in its first few washes.
• Drying: Line dry where possible. Dry dark colours in the shade, since strong sun fades cotton over time. If using a dryer, choose low heat and remove items while slightly damp.
• Ironing: Cotton tolerates a hot iron. Woven shirts iron best while still slightly damp. Jersey t-shirts rarely need ironing if you hang or fold them straight after washing.
• Storage: Fold knits rather than hanging them to stop the shoulders stretching out.

Looked after properly, a well-made cotton garment can give you years of wear.

Cotton vs merino wool

Both are natural fibres, and both have a place in your wardrobe. They're just suited to different jobs.

Where cotton wins:

• Lower price for everyday basics
• Easy machine washing with few special requirements
• A smooth, crisp feel that suits casual and smart-casual wear
• Strong and hard-wearing in heavier weights

Where merino wool wins:

• Temperature regulation: Wool keeps you warm in the cold and comfortable when it warms up, which suits changeable conditions.
• Moisture management: Wool can absorb a significant amount of moisture vapour while still feeling dry, and it moves sweat away from the skin.
• Warmth when wet: Unlike cotton, wool keeps much of its insulating ability when damp.
• Odour resistance: Wool naturally resists odours, so it can be worn several times between washes.
• Softness: Fine merino fibres are soft and don't carry the itch people associate with coarser wools.
• Natural and renewable: Wool grows back every year and is biodegradable.

The trade-offs: Merino generally costs more than cotton and needs gentler washing, typically a cool wool cycle and flat drying.

The verdict: Cotton is great for relaxed everyday wear. For outdoor work, travel, the hills or any day where the weather might turn, merino is the stronger performer. It's why wool has been at the heart of Swanndri since 1913.

Is cotton good for outdoor or active wear?

Honestly, not usually. Cotton is fine for a gentle walk in fine weather or a casual day outside, but it isn't built for sweat, rain or cold.

Once cotton gets wet, from exertion or the weather, it holds that moisture against your skin, dries slowly and loses its warmth. In cold, wet or windy conditions, that can leave you uncomfortably chilled and, in serious outdoor situations, increases the risk of hypothermia. It's why many hikers, trampers and outdoor workers avoid cotton as a base layer.

For active or outdoor use, wool is the better choice. Merino regulates temperature, manages moisture, stays warm when damp and resists odour over long days. It's what New Zealanders have relied on for generations in the bush, on the farm and in the hills.

The bottom line: Keep cotton for everyday comfort. When you're heading outdoors, reach for wool.

Shop our cotton t-shirts for everyday wear or explore our merino wool range for the outdoors.