Why Do We Need to Glaze the Pastries
Glazing is not necessary but without any glazing, a pastry won't feel like a pastry as a glaze gives the pastry a glossy look, as shown below.
The glaze prepared for a pastry generally contains whole eggs, egg yolks, egg whites, sugar syrup, fruit glaze, milk or water. Sometimes even fruit juices are added along with other ingredients. It is normally applied by dipping the pastry into the syrup or applying it with a brush.
For a beautiful golden radiance to your pastry you must glaze it with an egg before putting it in the oven. Use the yolks for a profound mahogany gloss, or flatten your egg yolks by adding a little milk for a lighter gold finish. For applying glaze over sweet tarts and pies, you can mix the yolk with a little frosting sugar. To make a heavy glaze, brush a very thin sheet of your egg over the pastry by making use of a pastry brush, then you can let it dry in the refrigerator for about 10-15 minutes before applying another coat. You can do it as many times as you like to build up a deep golden coat.
Please follow this link to learn how to glaze french pastries. Why Do We Need to Glaze the Pastries