Do call ducks 'grey out'?

[Kleonaptra]

As mentioned above, ducks will molt multiple times a year. Drakes will often lose their color and look very dull. They will get the color and curly tail feather back though

But to also answer your question, black, blue, and chocolate ducks will "gray out". Each year they will get more and more white in color.
Pictured is a chocolate call drake (I no longer have him). I got him as a day old duckling. Fully feathered, he was solid chocolate. Each year, he would get a handful of white feathers. In this picture, he is 4 years old and quite "mottled" with white!

Im a little disappionted that my falgar will lose his black head, it looked very handsome. His brother Thorne wth grey head and white cheeks hasnt changed at all.