How to keep my whites white and the bright colors bright
There are several reasons why clothes lose their brightness. Common factors include the use of too much/too little detergent, too large washer loads, inadequate rinsing, and using the wrong water temperature. Read the detergent package for the correct amount of detergent for your type of washer.
If the washer is too full, there’s more rubbing/abrasion on the clothes, which dulls the fabric/colors. Don’t overload, and use the right amount of water for the load.
Regarding the temperature, follow the care instructions on the garment label.
Periodic use of appropriate fabric bleach (all fabric or chlorine, as appropriate) and/or laundry boasters will help keep clothes bright. Sometimes changing detergents may help.
Many clothes have optical brighteners or fluorescent whitening agents (FWAs) applied, which help brighten colors. Unfortunately, if the FWA are damaged by sunlight, bleach, or simply ageing, there is nothing you can do.