Some darker fabrics turn into different shades of orange and yellow before they become complitely white when bleaching. Some never turn to white. Asher Levine explores this bleaching technique in his Summer 2011 collection with tops and shorts. The garments are first folded and then raw bleach poured onto the fold edges (remember to use gloves!). The color effect becomes from the fabric reacting with the bleach. Put the garment into washing machine immediately when color and bleach pattern look like what you want. When sourcing for material, take a small medical glass bottle of bleach with you to the thrift store or fabric shop. I used to do this while studying to test the bleach effect on a small sample piece before I bought the material. I bet that Asher also overdyed this piece with a light gray color after the bleaching to get the color tones down and dirty looking.