I'm wondering if you could dip one end of the fabric in a bleach solution. Then rinse the fabric to stop the bleaching/shading process. Redip the very end to make it lighter, and rinse again. What ever you do, I would recommend rinsing the bleach out of the fabric before drying. I would think the bleach would so some damage if left in the fabric. Do try on a small sample first. My neighbor has done some experimenting using bleach, and found that some fabrics won't fade at all, and others change colors completely. I remember her using a couple different black fabrics. Both 100% cotton. One bleached to a beautiful red. The other an ugly brownish. As mycquilter suggested, dying may be an option.