study no. 03
Yellowing is the reason most white t-shirts are replaced. This study shows that it is not one problem but two, and that both can be solved. The first is the slow dulling of the whole garment, decided by the fabric and its care. We built our tee to withstand it: genuine Supima, long-staple, densely knitted at 200 grams, and tested side by side against other white tees, which yellowed far sooner while ours stayed white. The second is the mark that can form under the arms. It does not come from the fabric at all, but from a reaction between sweat and the aluminium in most antiperspirants — and a reaction can be prevented. Drawing on published chemistry and on our own wear and wash testing, this study sets out where the yellow comes from, every decision we made to keep the white, and the three simple habits that keep the whole tee white.
§ 1the white tee everyone has owned
Almost everyone has owned it. A white tee that was bright in the shop and clean on the first morning — and then, slowly, quietly, not quite white anymore. A faint cream across the body. A shadow under the arms. A garment that once looked intentional and now looks tired.
Most people accept this as the nature of white. We did not. Before we made a single decision about our tee, we set out to understand exactly where the yellow comes from — because a problem that is understood can be solved.
§ 2two kinds of yellow
The first thing we learned is that "yellowing" is not one problem. It is two, with different causes and different solutions. Most brands never separate them. Once they are separated, both become manageable.
| the whole tee dulls | the underarm marks | |
|---|---|---|
| Where | Across the body of the garment | Under the arms only |
| Cause | Oxidation of the fibre, body oils, heat, harsh washing | Sweat reacting with the aluminium in antiperspirant |
| Decided by | The fabric, and how it is cared for | The deodorant, and how the tee is washed |
| Solved by | The right fibre — which we chose for you | Three simple habits — which we give you |
Two causes. Two solutions. Both within reach.
§ 3the yellow that comes from the fabric
The dulling of a whole white garment is mostly a story of oxidation. Cotton is cellulose, and cellulose ages when it is exposed to light, heat and humidity. Body oils left in the fibres accelerate the process; a hot wash or a hot dryer accelerates it further.3
Two more things make it worse. Chlorine bleach, the instinctive remedy, weakens the cellulose and leaves it more prone to yellowing.3 And many inexpensive white tees are made to look whiter than they are, with brightening treatments that wash away over time.5 When the borrowed brightness leaves, the true colour of the fabric is all that remains.
This is the yellow a garment can resist — and it is decided, above all, by the fabric. Which is where we began.
§ 4everything we did to keep the white
We treated the white as a design problem, and made every decision we could in its favour.
| decision | why it protects the white |
|---|---|
| Genuine Supima | Extra-long staple cotton, certified and traced to its origin. The finest raw white we could find.4 |
| Long-staple fibre | Longer fibres spin into a smoother yarn, with fewer loose ends where oils and residue can settle. |
| Dense knit, 200 g/m² | A dense, closed surface holds less and releases more in the wash.7 |
| Tested against other tees | Worn and washed side by side with other white tees before we committed to it.6 |
| Nothing left to chance | We tell you the few simple habits that keep it white. |
Then we put it to the test. Our tee was worn and washed alongside other white tees — including a Supima-certified tee from a large mass-market label — in the same way, through the same cycles.
| other white tees | the white tee | |
|---|---|---|
| Body of the tee, after repeated washing | Began to yellow, much sooner | 100% white |
| Underarm, with an aluminium-free deodorant | — | 100% white |
| Underarm, with a regular antiperspirant | Yellowed quickly | Only a trace, far later — easily lifted |
The tee kept its white. With the right deodorant, so did the underarm.6
§ 5the yellow under the arm — and how to prevent it
Sweat itself is colourless.1 The mark people find under the arms of their white tees is not sweat, and it is not the fabric. It is a reaction: the aluminium compounds in most antiperspirants meeting the proteins and fats in underarm sweat, and settling into the cloth.1, 2
A reaction needs its ingredients. Remove the aluminium, wash the residue away before it builds, and the reaction has nothing to work with.
§ 6three simple habits
The fabric does the hard work. What remains is light: three habits, none of which take more than a moment.
| habit | why |
|---|---|
| An aluminium-free deodorant | No aluminium, no reaction. The underarm stays white.1 |
| A cold wash | Cold water protects the fibre and its white.3 |
| Air dry | Air keeps the cotton young. That is all.3 |
The right fabric keeps its white. Three habits keep the rest.
§ 7if a trace ever appears
If a trace of yellow ever appears under the arm, it is not a flaw in the tee. It is a residue resting on the fibre — and a simple soak with a gentle, oxygen-based stain remover before the next wash lifts it.2
A strong fibre makes this easy. Supima is considerably stronger than ordinary cotton,8 so it can be treated without thinning or losing its surface. The mark leaves. The tee stays.
§ 8what we promise
We promise a fibre and a fabric chosen to keep their white: genuine Supima, long-staple, densely knitted, without a borrowed brightness that washes away — and tested against other white tees until the result was clear.
Everything that depends on the garment, we have done. What remains happens on the skin, not in the fabric — and three simple habits take care of it.
Other brands tell you their white will last. We would rather show you why ours does, and exactly how to keep it.
§ 9conclusion
Most white tees are bought knowing they will not last. They are replaced every season, quietly, without anyone expecting more.
We expected more. We traced the yellow to its two sources. The one that comes from the fabric, we designed out: the finest raw white we could find, a long-staple fibre, a dense knit, tested against other white tees until the result was clear. The one that comes from the skin, we explained — and it takes no more than three simple habits to prevent.
Nothing that could be decided has been left to chance. What remains is a white tee that stays white, and a clear account of how to keep it that way.
It will not be the last white tee you hear about. It may be the last one you need to replace.
references & notes
- Sweat is colourless; underarm (apocrine) sweat contains fats and proteins that react with aluminium compounds in antiperspirant. Prevention: aluminium-free deodorant, letting deodorant dry, enzyme detergent. Mental Floss, Why We Get Sweat Stains, with SciShow.
- Aluminium compounds in antiperspirants combine with sweat to form yellow marks on white clothing; chlorine bleach can react with sweat stains and give them a yellow tint. Degree, How to Remove Sweat Stains from White Shirts.
- Cotton yellowing through oxidation of cellulose, accelerated by body oils, sweat, heat, light and humidity; chlorine bleach weakens cellulose fibres. SELVANE, How to Remove Yellow Stains from White Cotton.
- See Study No. 04 — On Supima: not all Supima is the same.
- On whitening treatments and borrowed brightness, see Study No. 04, § 3.
- Wear and wash testing conducted by the white tee, worn daily by a single wearer who sweats heavily, compared side by side with other white tees, including a Supima-certified tee from a mass-market label. Underarm results observed both with an aluminium-free deodorant and with a regular antiperspirant. An in-house observation, not a laboratory test.
- On fabric weight and density, see Study No. 05 — On Weight: the search for the right thickness.
- Supima extra-long staple fibre is reported to be up to 45% stronger than conventional cotton. Fibre2Fashion, What is Supima Cotton Fabric.
a study series · first edition