I have a friend whose daughter is allergic to eggs, which led me to wonder about the classic egg wash, used to add lovely color to breads. I did a little research, and learned that you can do a wash with egg whites only, with heavy cream, even just with milk (done when funds are tight).
In this first photo, the curry buns on the left were baked with no wash at all; the ones on the right with a traditional egg wash. Interestingly, the bottom left one did brown a little, but certainly you got a more consistent, richer result from the egg wash.
Then I tried using just whites, and just heavy cream. The whites browned almost as well as the traditional egg wash; the heavy cream gave a little color, but I’m not sure it’s enough that I’d bother with it, honestly.
No real conclusions here — but it was fun experimenting!