This chart has seven of the most commonly used pastry washes. If you are wondering what the differences are between washes using egg, dairy, or plain water, then this chart will help.
The pastry washes in this chart are arranged to show gradual changes from top to bottom, with egg washes toward the top, dairy in the middle, and water at the bottom. A whole egg wash gives a lovely brown color to baked goods. It seals and shines well and toppings will adhere best with this wash. Just plain water seals any pastry well and helps with adhering toppings, but doesn't work for browning or shine.
A wash that is specified in a recipe is chosen thoughtfully for what it needs to do to enhance the pastry, as some help with browning and some are best at adhering seeds, spices, or sugars.
My personal favorite pastry washes are a whole egg with water wash and a plain egg white wash. Find the best wash for each of your baked goods in this chart.