Cotton underwear can last ages and feel great for longer, but only if it is washed with a bit of care. The biggest issues are simple, heat that is too high, detergent that is too harsh, and drying that damages fibres over time.
This is the practical guide to keeping cotton underwear soft, comfortable, and well fitting, without turning laundry into a hobby.
1. Use cooler water than you think
Hot washes feel reassuring, but heat is what breaks down cotton fibres faster and makes elastic lose its recovery.
A good rule
30 degrees is ideal for most washes
40 degrees only when you need extra cleaning
60 degrees is rarely needed and usually too harsh for regular wear
If you are worried about hygiene, focus on a good wash routine and full drying, not constant high heat.
2. Choose the right detergent, gentle wins
Overly strong detergent can leave residue and make fabric feel stiff. Scent boosters can do the same, and they can irritate sensitive skin.
What to use
A gentle detergent
As little as you can get away with, especially if you have soft water
A fragrance free option if you are prone to irritation
What to avoid
Heavy fabric softener, it can coat fibres and reduce breathability
Too much detergent, it traps residue in the fabric
3. Protect the shape, use a wash bag
If you want cotton underwear to stay looking new, a mesh wash bag is one of the simplest upgrades. It reduces friction, stretching, and snagging, especially if you wash with jeans, zips, or towels.
If you only do one thing from this guide, do this.
4. Wash with similar fabrics
Cotton underwear does best when it is not being battered by heavy items.
Try not to wash it with
Denim
Towels
Anything with hooks or zips
If you do need to combine loads, at least use a wash bag.
5. Skip fabric conditioner, it is not your friend here
Fabric softener can make cotton feel slick at first, but it tends to coat fibres, which can reduce breathability and affect how the fabric sits against skin.
If you want softness without conditioner
Use the correct amount of detergent
Rinse well
Air dry when you can
6. Drying is where most damage happens
High heat is the shortcut to losing shape and softness. It can also shorten the life of elastic.
Best option
Air dry flat or draped naturally
If you use a tumble dryer
Use a low heat setting
Do not over dry
Remove while slightly damp and let it finish air drying
7. Treat stains quickly, no harsh scrubbing
If you need to spot clean, do it gently.
What works
Cool water
A small amount of gentle detergent
A short soak if needed
Avoid
Very hot water
Aggressive scrubbing
Bleach, it can weaken fibres and elastic
8. Storage matters more than people think
If you crumple cotton underwear into a tight drawer, it will crease, and elastic can deform over time.
Better
Fold loosely
Do not over pack the drawer
Keep it away from damp areas
A quick care checklist
30 degree wash for everyday care
Gentle detergent
Use a mesh wash bag
Skip fabric softener
Air dry when possible
Low heat only if using a dryer
Where String Nix fits in
String Nix makes one piece, a String Nix string thong designed to sit smooth and feel barely there under clothes, with smooth sides, a stable waistband, and breathable organic cotton. If you want it to stay soft and hold its shape, treat it gently, and it will reward you with comfort wash after wash.
FAQ
What temperature should I wash cotton underwear
30 degrees is ideal for regular washing, 40 degrees is fine occasionally, higher heat is usually unnecessary.
Can I tumble dry cotton underwear
Yes, but use low heat and avoid over drying, air drying is better for shape and softness.
Should I use fabric softener on cotton underwear
It is better not to, it can coat fibres and reduce breathability, a gentle wash routine keeps cotton soft naturally.
