EDIT: A real life example of silver hair I made for someone which might be useful to show other people as well: sta.sh/02fwsbsid643
I got a request for white hair palettes and felt I needed to go a little more into detail about white hair as well as black hair, and the common mistakes I see. I hope this is helpful and if you have questions or tutorial requests, just post a comment asking c:
i probably still wouldnt suggest using greys for it..though you can if you want cause I'm not stopping anyone at the end of the day XD But maybe use desaturated browns? It really depends on what type of dirty look you're going for.