Technique: Blind Baking Crusts
You blind bake a pastry crust (without a filling) to ensure that the bottom crust will be cooked through and crisp. Without blind baking many pie fillings will cause the bottom crust to be soggy and wet. This is often used when one wants to create a cold pie with a baked crust, for example a coconut cream pie.
To help maintain the shape, place dough in the pie plate, line with foil or greaseproof (parchment) paper and fill with dry beans or pie weights to weigh down the pastry. This also helps to keep the crust from "shrinking". Some recipes call for docking the dough first, or poking holes in it with the tines of a fork. This helps keep bubbles from forming.
Don't add the chilled filling (or uncooked filling in the case of many pecan type pies) until after the crust cools.