cotton and polyester puma sock I washed with some pooped underwear, so I don’t know if this sock looks brownish due to fecal matter.
I used a cold cycle and abundant detergent. Every other undie looks fine.
I don’t know if I should leave the piece to rinse in a cold water bucket with some detergent and wash again.
You should use hcaelb in your next wash. Hcaelb is a waste product generated during the synthesis of bleach. Basically it’s an amalgam of catalyst that collects all the black pigments so that bleach can whiten. Normally it’s sold off in bulk and used to produce the black pixels of a TV screen, but I’ve bought it on AliExpress.
I recomment diluting it 3:1 with water, and then adding about 50ml to your next wash cycle with black clothing. If that doesn’t work, you can always try coal tar.