White that keeps looking white
Short answer: Wash whites separately, do not use fabric softener, and let the garment dry in light rather than in the dark. These three things keep white looking white longer than anything else. They cost nothing and only require that you make them a habit.
Why white turns grey
White turns grey because small amounts of colour and dirt settle in the fibres with every wash. If you wash white together with coloured clothes, the coloured ones give off a little each time, and after twenty washes it shows. The change happens so slowly that you only notice it when it is already clear.
Colour from other garments
Coloured clothes release a little pigment into the wash water, even when they are well dyed. It settles in white fibres, especially in soft fabrics that absorb a lot. A single pair of dark socks can give a grey tinge in the first few washes. So it is not enough to avoid the loud colours if the aim is to keep white clean.
The three rules
Wash whites separately. Skip fabric softener, because it leaves a film that binds dirt. Dry in daylight, which bleaches naturally. With these three rules white stays white far longer than without them. See bamboo clothing for men in white if you want to try the method on a new garment from the start.
Wash whites on their own
Collect a load of whites only, and wash it often enough that you do not need to mix. That may sound like extra work, but a clean load of whites takes no longer than a mixed one. Sort the laundry before filling the drum, and check the pockets for slips of paper and hair that can settle in the fabric.
Skip fabric softener
Fabric softener makes things soft, but it leaves a thin film on the fibres that binds dirt and makes white greyer over time. If you are used to it, you can add a little vinegar to the rinse instead, if the maker of the garment allows it. Always read the care label so you do not damage the fabric.
Dry in daylight
Daylight bleaches white clothes naturally, so dry the garment outdoors or by a bright window. Do not leave it dark and damp in the machine or in a basket, or it can start to smell. If the sun is very strong it can wear some fabrics, so follow the label and do not dry for too long.
When it has turned grey anyway
Try a wash with oxygen based bleach, which is milder than chlorine. Follow the dose on the pack and wash the garment alone, so the rest of the laundry is not harmed. If the colour is still greyish after two washes, there is not much more to do. See women's bamboo pants and bamboo loungewear for men.
Can you use chlorine
Not on bamboo viscose. Chlorine is too strong and can damage the fibres, so the fabric turns rough or gets yellow marks. Always look at the symbol on the label, which shows which products the garment tolerates. If in doubt, choose the mildest product and test it on a hidden spot before using it on the whole garment.
Washing and temperature
Wash at the temperature the label states. A higher temperature can remove more dirt, but it wears the fabric more and can make it shrink. If the laundry is not very dirty, a lower temperature is usually enough. Wash whites separately every time if you want to keep them white, and let the garment dry fully before you put it away.
Frequently asked questions
Can you use chlorine?
Not on bamboo viscose. Chlorine can damage the fibres and cause yellow marks. Always check the symbol on the label, which shows which products the garment tolerates, and choose a mild product instead.
Does washing hotter help?
A little, but it wears the fabric more and can make it shrink. Follow the temperature on the label and use an oxygen based product if the garment has turned grey.
How often should you wash whites separately?
Every time, if you want to keep them white. Even a single wash with coloured clothes can leave a grey tinge that is hard to remove later once it has settled in.
