This article was originally written in French, our native language. Apologies in advance if anything reads a little awkwardly – you can write to us at hello@loom.fr to help us improve our translations.

When we ask for our customers' feedback after a year of wear, one of the first issues to come up is that white clothing (especially t-shirts and shirts) yellows or turns grey over time. There can be lots of reasons for this: colours running in the wash, sweat, tomato sauce stains…

Avis clients tshirt loom

Yellowing isn't about the quality of the garment—it's about how you care for it. To keep your clothes from yellowing, one thing really works: washing whites separately. I know, it’s a hassle, because you end up waiting weeks for your laundry basket to fill up just to run a load of whites. Still, it’s what works best. It makes sense: clothes go dull because they absorb the dye from other items in the machine. So, if you only wash them with other white items that don't bleed... But I imagine it’s already too late and you’d like your garment back to its (almost) snow-white glory. Good news: there is a trick that works for cotton, Tencel, linen, and synthetic fabrics (but not for wool or silk) that:

  • Doesn’t take much effort,
  • Is cheap,
  • Doesn't require any harsh chemicals.

And that trick is called:

percarbonate de soude

Sodium percarbonate is an odourless white powder made of sodium carbonate (or soda crystals) and hydrogen peroxide:

  • The soda crystals clean,
  • The hydrogen peroxide whitens.

I recommend the one from the brand La droguerie écologique, because I can find it in any organic shop, because it comes in simple kraft paper packaging, because it's made in Europe, but mostly because it's inexpensive: €5 per kilo. ⚠ Careful: unlike baking soda, sodium percarbonate is a potentially irritating product, so handle it with care. When using it, we recommend wearing protective gloves and opening a window to ventilate the room.

The process is quite simple

  1. Place the clothes you want to whiten in a plastic basin. Warning #1: if you include light-coloured items that aren't pure white (like beige), they will come out significantly lightened. And warning #2: if you put items that aren't completely white in the basin (with coloured piping, for example), there is a risk that these small accents will bleed onto the rest of the white clothing. In short: we recommend following this tutorial only with items that are truly white.
  2. Fill the basin with very hot water until your clothes are completely submerged. I really want to emphasize "very hot": use the hottest water from your tap (the whitening power of percarbonate is most effective at 60°C/140°F or higher, and your water heater is generally set to 65°C/149°F).
  3. Add the equivalent of a glass of sodium percarbonate. Caution: when you add the sodium percarbonate, your mixture will double in volume. Be sure not to fill your basin more than halfway and keep it in your sink or shower, so that if it does overflow, it won't spill onto your floor.
  4. Stir with a wooden spoon (one you no longer use for cooking) or a stick (basically, something wooden that you won't be putting in your mouth after this),
  5. Go about your business,
  6. After an hour, pour a kettle of hot water into your basin and stir again with the wooden spoon or stick (at this stage, the volume will not increase, unlike in step 3),
  7. Forget about your basin overnight, and by the next day your whites will be revived and the stains gone!
  8. One run through the machine with your other whites and job done!

But does it actually work?

Clément (from the Loom team) had two older-generation Loom t-shirts at home that he didn't wear anymore because he thought they’d gone too grey.

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Left: one of Clément’s “greyed” t-shirts. Right: a brand-new, unworn t-shirt (so, nice and white).
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Basin + clothes + percarbonate + boiling water = diamond-bright whites for your clothes.
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Ta-da! Left: Clément’s greyed t-shirt. Right: the new t-shirt. Middle: Clément’s other greyed t-shirt after a night in a basin of sodium percarbonate.

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Who am I to talk about garment care?

My name is Claire and I’m in charge of production monitoring at Loom. Basically, I try to prevent stock shortages on our site and ensure that our clothes meet our quality standards throughout every stage of production. On top of that, I’m passionate about anything that helps extend the lifespan of our clothes: care, repairs and other grandmother’s tricks. I love giving clothes a little extra soul—reworking them, repairing them, and giving them a second chance when no one else wants them. On these pages, I’ll try to share what I know that might be useful to you. One last thing: I’ve personally tested every tip you’ll find on this site to make sure they actually work (in other words, this isn't just a copy-paste of internet searches). If you have new ones to suggest, feel free to leave a comment below this article.

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