Patching the Crust: Pastry crusts sometimes develop a split along the bottom (usually during the weighted phase of baking) or shrink down the sides of the pan (usually after the weights have been removed and during the final baking). If the crust is to hold a thick, fully cooked mixture, as in cream, chiffon, or lemon meringue pie, small imperfections can be ignored. But if you are filling the crust with an uncooked liquid mixture, as in custard, pecan, chess, or pumpkin pie, all cracks need to be patched, or else the filling will leak through. Using your fingertips,
press reserved dough scraps into the required shape, lightly moisten one side with water, and press the moistened side over the problem area of the baked crust. If you have no scraps, make a thick paste with flour and water and smear it over the tear with your fingers. The crust need be returned to the oven only long enough to harden and dry the patch, not to brown it and bake it through. If glazing the crust with egg yolk before filling, be sure that the edges of the patch are completely sealed with yolk.
