THREE TIPS: KEEP YOUR WHITE SHIRT WHITE
1. FORGET BLEACH
It may come as a surprise, but the best way to treat a white, non-iron shirt is to use coloured detergent. White laundry detergent often contains bleach, which might react with the chemical treatment the shirt has been given during manufacturing in order to be white. Also, do avoid those pesky stain removers. They just make matters worse.
2. FORGET FABRIC SOFTENER
Fabric softener does not make the clothes cleaner, nor does it have any evident effect on the actual softness of the shirt. Fabric softener also contains chemicals, which in turn are harmful for the environment. Certain white textiles may also become discoloured from the chemical reaction, which would be a terrible waste of a beautiful white shirt.
3. USE THE CORRECT DOSAGE
More detergent does not make for cleaner clothes either. It merely increases the amount of enzymes and might reduce the lifespan of the shirt as well as discolour it. But no matter which detergent you use, make sure to use the correct dosage. This is good for the environment and your wallet. Essentially just a win-win situation all round.
Should your shirt be tinting towards yellow, here is a few tips on how to make it all crisp and white again.
The first method requires liquid, colourless dishwasher detergent and citric acid. Mix it together and add a little cold water for a liquid consistency. Leave it on the stain(s) for approximately 20 minutes or so, and wash in the machine after the labelled instructions.
OR alternatively, although it's not the most sustainable method, wash as usual but use a detergent with optical brighteners.