Board Thread:Naruto Discussions/@comment-4682609-20140806081616/@comment-1018594-20140808163936

Victory9000 wrote: If I remember correctly Susanoos are based on the owner's chakra colour, which is normally unable to be seen unless it's amazingly powerful like Zabuza. I don't think it was explicitly said that the reason why Sakumo and Kakashi's blade gave off a white streak when swung, but seeing as it's a family heirloom it's seems reasonable it gets the white from that particular family's chakra, assuming that chakra colour can be passed down through genetics. People who are related do share similar chakra, so it very well could be some shade of gray/white.