How can I remove detergent stains from a a black cotton blouse?

Question

I've rewashed it without detergent over and over again.

Answer 1

Soak the article in cold water.  Soak for about 2 hours.  After that, send the shirt back through the wash......dont use any powder detergent.....use liquid.....the stains should be completely gone after this.

Answer 2

Rewash without detergent.  Put in fabric softener so it will soften the water and release the detergent.  Sounds like there where too many clothes and the soap was put in on top of the clothes.  Next time put the water then the soap and then the clothing.  I only use this on black and dark clothing.