I used
http://www.wawak.com/products/produc...s-Chalk-White/ to mark on dark materials that can be ironed.
I've never had great luck with the white vanishing ink fabric pen personally, so on materials that can't be ironed I use silver Sharpie markers. But that only works if you're marking on the wrong side of the fabric and the fabric is dark enough that any minor bleeding that occurs in the wash isn't an issue.