Keeping whites white, with and without bleach

Whites don't turn grey in one wash. They pick up a little loose dye from a stripe here, a little body oil that never quite rinsed out there, some detergent residue, some minerals from hard water — and one day the T-shirt that was white is a colour that doesn't have a name. Most of that is preventable, and most of the damage can be undone.

Why whites go grey or yellow

• Dye transfer from anything colored in the same load, even a pale one.
• Body oil and sweat that a cold, short wash doesn't fully dissolve — the yellowing under arms and at collars.
• Detergent residue from overdosing, which dulls the surface and attracts dirt.
• Hard water minerals, which leave a grey film over time.
• Underdosing in a full load, which leaves dirt to redeposit on the fabric before it rinses away.

The routine that prevents it

• Sort strictly: whites alone, not with anything pastel or striped. See how to sort laundry by color.
• Wash at the warmest temperature the label allows — for cotton whites, that's usually 60 °C — because oils dissolve in warm water and stay put in cold. Check the label; synthetics and elastane whites still want cool water.
• Dose detergent properly for the load size and your water hardness. Both too little and too much lead to grey.
• Don't overload, so the water can carry the dirt away.
• Dry in the sun when you can — sunlight has a mild bleaching effect on cotton and linen.

Reading the bleach triangle

• A plain triangle — any bleach is allowed, chlorine included.
• A triangle with two diagonal lines — only non-chlorine (oxygen) bleach.
• A crossed-out triangle — no bleach of any kind.

The triangle is the symbol most often ignored, and the one that costs the most when it's wrong: chlorine bleach on a garment marked for oxygen bleach only can yellow it permanently.

Oxygen bleach

Sold as powders and as the active ingredient in most "color-safe" bleaches and stain boosters. It releases oxygen in the wash to lift stains and brighten, works best in warm water, and is safe on nearly everything colorfast, including most colors — which makes it the right default for whites with any synthetic or elastane content. For grey or yellowed whites, a long soak in warm water with oxygen bleach before a normal wash brings back a surprising amount.

Chlorine bleach

Stronger, faster, and far less forgiving. It's for sturdy cotton and linen whites whose label shows the plain triangle, and nothing else: it damages wool, silk and elastane, and can yellow polyester and nylon. Dilute it as the bottle says and add it to the water rather than pouring it onto fabric. Never mix it with ammonia or with acids such as vinegar — the combination releases toxic gas. If you're not sure a garment can take it, it can't.

Other things that help

• Detergent with optical brighteners — most mainstream detergents for whites contain them; they make fabric reflect more blue light so it looks whiter.
• A hot wash now and then for cotton whites that are usually washed warm.
• An extra rinse when whites have been looking dull, to clear residue.
• Treating collars and underarms with detergent or oxygen bleach before the wash, rather than hoping the cycle gets them.

LaundryMax reads the bleach triangle along with everything else on the label, so you know which whites can take chlorine and which need oxygen bleach before the load goes in. See how it works.