Board Thread:Naruto Discussions/@comment-4682609-20140806081616/@comment-24071637-20140808114743

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.