Could be two different things that come to mind.

Bleach stains on black clothing. The bleach must be attended to quickly. You can use sodium thiosulfate to remove chlorine stains from clothing. Put straight white vinegar on the yellow stains.

Then, start to rub the cotton wool ball from the outside of the stain towards the centre. When done, you will wash the pants in a washing. Bleached spots on the fabric removing the color.

Sodium thiosulfate counteracts the effect of bleach, but may not be effective on dark clothing or on an old stain. If it is still in the middle of the discolored area, then you could try using a fine tip black pen to carefully color up to the butterfly, but not over it. Dilute 1/4 cup of bleach with 1 gallon of water.

Another solution that can neutralize bleach comprises of hydrogen peroxide and water. It's important to remember that bleach and white. When this is done, you should then rinse your clothing in the wash.

Use a cotton wool ball to. Allow it to sit for 5 minutes. Bleach stains on clothes are actually dye free area where bleach has removed the color from the fabric.

It will, however, prevent the bleach. If you use a concentrated bleach formula, use 2 to 3 tablespoons of bleach in 1 gallon of water. After 5 minutes, take a dry cloth.