Final answer:
The mixture of egg yolk and milk or water that bakers often paint on top of sweet rolls to make them attractive and shiny is called an egg wash.
Step-by-step explanation:
The mixture of egg yolk and milk or water that bakers often paint on top of sweet rolls to make them attractive and shiny is called an egg wash. An egg wash is made by beating together egg yolk and a small amount of milk or water until well combined. The mixture is then brushed onto the surface of the dough before baking. When the sweet rolls are baked, the egg wash gives them a golden brown color and a glossy finish.