1) soak shirt in white vinegar / water (1 part to 4) for 1-4 hours (or overnight) 2) apply liberally a paste of baking soda & hydrogen peroxide to yellowed are

1) soak shirt in white vinegar / water (1 part to 4) for 1-4 hours (or overnight) 2) apply liberally a paste of baking soda & hydrogen peroxide to yellowed areas 3) let rest for 1-2 hours 4) wash normally Bonus: use Bluette every few washes.