An Apology to Every Pair of Briefs I Have Wronged
An apology to seven garments I destroyed through carelessness, and the laundry lesson buried in each. A care guide in the shape of a confession.
How to Wash Underwear Properly
How to wash underwear so the elastic survives: the right temperature, why fabric softener wrecks cotton and synthetics differently, and when to go hot.
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Most men's underwear does not wear out. It gets killed, repeatedly, in a machine, by its owner, over a period of about eighteen months, and then the owner concludes that underwear does not last any more and buys another multipack.
The waistband goes first. It stops snapping back, then it starts to ripple, then it rolls over on itself at the hip and stays there. The leg openings curl and twist into a cord. The white goes grey. The seat bags. Every one of those failures has a specific cause, and in almost every case the cause is a laundry decision rather than an hour of wear Buy It Once: The Durability Guide to Briefs That Last Years.
Elastic dies of heat, not of age
Start with the single most useful fact in laundry, because everything else follows from it.
Elastane, also sold as spandex or under the trade name Lycra, is a segmented polyurethane. It works because the molecule contains soft, coiled segments that stretch and hard segments that pull them back. Heat is the enemy of that arrangement in a direct, physical way: raise the temperature enough and the hard segments soften, the polymer relaxes into a new shape, and the recovery you paid for is gone. It does not come back when the garment cools.
Agitation does the same job more slowly. Every wash cycle flexes the fibre thousands of times, and a fibre flexed while hot deforms far more readily than one flexed cold.
So the useful mental model is not "my underwear is three years old". It is "my underwear has been through two hundred cycles, of which forty were hot and sixty went through a tumble dryer". Two identical pairs bought on the same day can be five years apart in condition depending purely on how they were treated.
Chlorine attacks elastane by a separate route, which is why swimwear has its own rules and its own article Chlorine, Salt and Sun: How to Make a Swim Brief Last.
The temperature answer
Wash at thirty degrees. That is the default and it is right for the overwhelming majority of loads you will ever run.
Thirty with a decent detergent removes body soil and sweat comfortably. Modern detergents are formulated for it; their enzymes work at low temperatures and some are actually less effective when you cook them. Cold washing is gentler still on elastane but struggles with the oily component of body soil, which builds up invisibly and then announces itself as a smell you cannot shift.
Forty degrees is acceptable for cotton you are not precious about, a small withdrawal from the account rather than a disaster. Sixty is a tool rather than a setting, and there are two occasions when you should reach for it, both covered further down. Ninety is for tea towels.
The other settings matter almost as much as the dial. Use a lower spin speed than the default, because the spin is the most violent part of the cycle and does real mechanical work on a fine knit. Do not stuff the drum; a packed machine agitates garments against each other rather than through water, which is abrasion.
Fabric softener ruins two different fabrics in two different ways
No version of fabric softener belongs anywhere near underwear, and the reason is worth understanding because it is not the same reason in both cases.
Softener deposits a thin cationic film on the fibre surface. That film is essentially a lubricant, and it is what makes towels feel plush in the shop and hopeless in the bathroom.
On cotton, the film sits on top of the fibre and blocks it. Cotton absorbs moisture because water gets into the cellulose structure; coat the outside with something water-repellent and you have made an absorbent fibre less absorbent. The fabric stops managing moisture and starts holding it against the skin, which is precisely the failure cotton is otherwise good at avoiding.
On synthetics, it does something worse. A wicking fabric works by capillary action through the spaces between fine filaments. Fill those spaces with a waxy deposit and the capillaries stop working. Sports kit treated with softener does not wick, and it holds odour more stubbornly, because you have laminated grease over the bacteria's food supply The Sweat Article: Moisture-Wicking Fabrics, Explained Properly.
The same logic rules out scented laundry beads and most "freshness" additives, which are the same chemistry in a different bag The Fabric Bible: What Your Briefs Are Actually Made Of.
The polyester odour problem, and how to fix it
Anyone who has owned technical kit knows the failure: the garment comes out of the wash smelling clean, you put it on, you warm up, and within ten minutes it smells like the inside of a gym bag.
There is decent science behind this. Researchers at Ghent University compared cotton and polyester T-shirts worn during a fitness session and found that micrococci, the bacteria most associated with textile malodour, grow markedly better on polyester. Those bacteria break long chain fatty acids from sweat into smaller, volatile ones, and those small molecules are what your nose registers. Fresh sweat is close to odourless; the smell is the bacterial work done on it afterwards. Polyester holds the oily residues feeding that process, and a cool wash does not necessarily remove them.
The fix is a detergent with a proper enzyme package, specifically lipases and proteases, which digest fats and proteins rather than merely lifting them. Use a full dose, not the optimistic small scoop. If a garment is already set in, a long soak in oxygen bleach powder, which is sodium percarbonate, will usually reset it where a normal wash will not enzyme laundry detergent.
Two habits prevent the problem entirely. Do not leave damp kit balled up in a bag overnight, which is a bacterial incubator with a zip. And do not let sports gear sit in the basket for four days waiting for a full load.
Wash bags, and why fine knits need them
A mesh wash bag is the cheapest upgrade in this article and the one most people skip because it looks fussy.
It stops fine garments being stretched around the drum ribs, prevents them tangling with sleeves and trouser legs, and keeps them away from anything with a hook, a zip or a hard fastening. A single jeans rivet passing through a fine gauge knit at spin speed will pull a thread, and a pulled thread in a fine rib is a permanent scar. Use one for anything fine gauge, merino or expensive. Sort while you are at it: towels shed lint that embeds in fine knits; denim abrades; zips cut mesh wash bag.
The tumble dryer is the fastest way to kill a waistband
If you take one instruction from this piece, take this one. Nothing else you can do to a pair of briefs is as destructive, and nothing else is as easy to stop doing.
A domestic dryer combines the two things elastane cannot survive. It runs hot, often hotter at the element than the setting suggests, and it tumbles, flexing every fibre continuously for the better part of an hour while it is hot. That is the exact combination that lets the polymer relax and reset at a new length. You will not see it in one cycle. You will see it after thirty, when the waistband no longer snaps back and the leg openings have started to curl.
The leg curling deserves a mention because men blame the style for it. A folded and coverstitched leg hem has fine elastic inside it, and when that elastic relaxes unevenly the hem starts to ripple, then curl, then rope into a twisted cord that sits across the thigh. A garment with a bound or flatlocked leg opening resists it far better, which is one more argument for looking at construction before you buy Anatomy of a Brief: Every Panel, Seam and Stitch Explained.
Cotton without elastane tolerates the dryer better, but it shrinks in the length rather than uniformly, so the rise drops and the garment stops fitting the way it did.
There is no low-heat setting that makes this fine. There is only not doing it. What eleven years of ignoring that does to a perfectly good brief is a confession of its own An Apology to Every Pair of Briefs I Have Wronged.
Drying flat versus hanging
Wet fabric is heavy and cotton loses tensile strength when wet. Hang a saturated garment by one edge and gravity spends several hours pulling it out of shape. For briefs, trunks and boxer briefs, hang them by the waistband over a rail rather than clipping one point, so the weight distributes across the whole band.
For anything knitted and heavy when wet, dry flat: merino base layers, wool socks, ribbed vests and anything with a loose gauge. A wool garment hung wet will grow, sometimes permanently, and the sleeves and body will not grow at the same rate The Best Merino Underwear.
Never dry on a radiator. It is the tumble dryer's problem in slow motion: direct contact heat, concentrated where the garment touches the metal, applied for hours. And keep colours out of direct sun, which is a genuine bleach. That cuts both ways, because sunlight is the best whitener there is for white cotton, and it costs nothing Why Underwear Is White.
Hard water and greying whites
White cotton does not usually go grey because of dirt. It goes grey because of what the water leaves behind.
In hard water areas, calcium and magnesium ions react with detergent and with soil to form insoluble deposits that build up in the fabric over successive washes. The result is a dull, flat grey cast that no amount of ordinary washing shifts, because ordinary washing is what put it there. Detergent residue from overdosing does the same, which is why using more powder to fix grey whites makes them worse.
Three things help. Use less detergent, not more. Add washing soda or a proprietary water softener, which binds the minerals before they bind to your clothes. And periodically soak whites in oxygen bleach, which lifts the accumulated deposit without the fibre damage chlorine bleach causes oxygen bleach powder.
Chlorine bleach is a last resort on white cotton and never an option on anything containing elastane, which it attacks directly. Optical brighteners mask greying by fluorescing rather than removing it The White Brief: A Cultural History.
When a hot wash is genuinely necessary
Having spent this article arguing for thirty degrees, here is the honest exception, because there are two situations where a cool wash is not good enough.
Fungal infection. If there is athlete's foot, jock itch or any other dermatophyte in the house, cool washing does not deal with it. A study of household laundering found that washing at forty degrees, with or without detergent, failed to reduce the viability of Trichophyton conidia, while sixty degrees and above did eliminate them. The same work found heat drying alone and freezing were both ineffective. So socks and underwear need sixty degrees for the duration of the treatment, and you should accept the cost to the elastane as the price of not reinfecting yourself indefinitely Wool Socks: The Outdoor Article.
Genuinely soiled or shared kit. Anything contaminated, anything from a hospital visit, anything shared. Sixty degrees, and take the hit.
Otherwise, hot washing is a habit rather than a decision, inherited from a household where detergents were much worse than they are now. Keep a few cheap cotton pairs for the hot pile so your good briefs never see sixty degrees at all cotton rib brief.
The whole routine, in one paragraph
Sort underwear away from denim, towels and zips. Fine knits and anything expensive go in a mesh bag. Thirty degrees, a full dose of enzyme detergent, no softener, reduced spin, drum no more than two thirds full. Hang by the waistband, or dry flat for wool, out of direct sun for colours and in it for whites. Never tumble dry, never dry on a radiator. Soak whites in oxygen bleach occasionally, and add a water softener if you live somewhere hard. Sixty degrees only for fungal infection or genuine contamination wool and delicates detergent.
Do that, and the difference is between replacing your drawer every eighteen months and replacing it when you have got bored of it, which is a better reason The Drawer Audit: How Many Briefs You Need and When to Replace Them.
Washing routines change for anyone managing leaks, where the priorities are different and the advice above needs adjusting rather than simply following Incontinence and Underwear: A Practical Guide Without the Euphemisms.
Questions people ask
What temperature should I wash underwear at?
Thirty degrees for almost everything. Modern detergents are formulated to work at low temperatures, and thirty removes body soil and sweat perfectly well while doing the least damage to elastane, which loses its recovery permanently when heated. Forty is acceptable for plain cotton you are not precious about. Reserve sixty degrees for the two cases that genuinely need it: household fungal infection, and properly contaminated or shared kit. Hot washing everything is a habit inherited from an era of much weaker detergents.
Does fabric softener ruin underwear?
Yes, and in two different ways. Softener deposits a waxy cationic film on the fibre surface. On cotton that film blocks absorbency, so the fabric stops taking up moisture and starts holding it against your skin. On synthetics it clogs the fine spaces between filaments that make wicking work, so technical fabrics stop performing and hold odour more stubbornly. Skip it entirely on underwear, socks and sports kit. Genuine softness comes from yarn and knit quality, not from an additive.
Why do my waistbands go slack so quickly?
Almost always heat, and specifically the tumble dryer. Elastane is a polymer whose stretch depends on hard segments pulling soft ones back; heat lets those hard segments soften and reset at a new length, and the recovery does not return when the garment cools. Tumbling adds continuous mechanical flexing while the fibre is hot, which is the worst possible combination. Hot washing, radiator drying and stretching the band to pull the garment on all contribute. Elastic dies of heat and agitation rather than of age.
How do I get the smell out of polyester sports underwear?
Use a detergent with a real enzyme package, particularly lipases and proteases, at a full dose. The smell comes from bacteria, mainly micrococci, which grow better on polyester than on cotton and break down the oily residues left in the fabric into volatile, smelly compounds. Ordinary cool washing lifts sweat but not always the oils feeding them. For set-in odour, soak in oxygen bleach before washing. Never use fabric softener on technical fabrics, and never leave damp kit balled up in a bag.
Why are my white briefs going grey?
Usually mineral deposits rather than dirt. In hard water, calcium and magnesium react with detergent and soil to form insoluble residues that build up over many washes and leave a dull grey cast. Overdosing detergent makes it worse. Use less, add washing soda, and periodically soak whites in oxygen bleach. Sunlight is free and highly effective.