Board Thread:Off Topic/@comment-25396609-20160125214134/@comment-28288412-20160921153812

-Still, the only Grimm that have broken the general colour scheme were artificially mutated. I doubt others could do so naturally.

-I disagree with Phantom that they can do it constantly if they so wished, but it does seem that they do shoot them by flapping their wings.

By using a special type of dust generally (gravity). The show isn't awful with keeping with physics, but U doubt they would hesitate to break it to make something happen.