Washing powder is alkaline, and the characteristics of citric acid itself can turn yellow. Acid-base neutralization also removed some residues from clothes. Some have been neutralized and some have been cleared. Clothes will turn white without some residual impurities and so on.

There are two main situations in which clothes have yellow spots. First, clothes tend to yellow as a whole over time, and sun exposure, including photoaging, is the reason why clothes tend to yellow. Second, there are some sweat stains left on the clothes, which will turn yellow if they are not cleaned.

When acid solutions such as citric acid and acetic acid are used for washing clothes, they can not only remove yellow, but also brighten the color of clothes and improve the softness of clothes.

Extended data:

Maintenance method of white clothes:

1. Skim milk: soak the white silk fabric with skim milk before washing, or add 2 tablespoons of milk in water for the last rinse to prevent it from turning yellow.

2, orange peel water: put the orange peel into the pot to boil, and then soak it in orange peel water and wash the clothes, so that the clothes can be as white as new.

3. Dropping ink: Drop 3 ~ 5 drops of pure blue ink in a basin of clean cold water, stir it evenly by hand, then put the washed white shirt in water, lift it up and down for 3 ~ 5 times, and dry it.

4. Adding hydrogen peroxide: 3% hydrogen peroxide can be used to bleach silk and wool fabrics, and the amount of liquid is 10 times the weight of the fabric, and a small amount of ammonia water is added to make it weakly alkaline. Soaking and bleaching at normal room temperature for 5 ~ 10 hour, then washing and drying.

5. Add lemon juice: When washing white silk fabrics, add some lemon juice to the water to make the clothes whiter.

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