Your pastry recipe may call for egg whites to be brushed on top of the pastry before baking. This is called an egg wash and gives a shiny, sometimes crackled appearance to the top of the pastry. If you can't eat eggs or prefer a different kind of look for the top of your baked goods, leave off the egg wash or substitute it with a different wash.
Cream or Milk
A thin wash of cream or milk acts as a glue to help seeds or sprinkles adhere to the top of baked goods. Unlike egg wash, however, these dairy products will not result in a shiny crust. You will achieve a browner crust with cream or milk, thanks to the Maillard Reaction, which is a browning process similar to caramelization. The enzymes and sugars in the cream and milk react with heat to create an appealing brown crust on the top of your baked goods.
Like cream and milk, butter helps produce a crust with a bakery-brown appearance. Unlike an egg wash, the crust will be matt, rather than shiny, and soft, rather than crisped. A melted butter wash works well with breads and rolls, giving them a soft crust and rich, buttery flavour. Apply the butter after you have baked your pastries or breads, rather than beforehand. For recipes with a crust, like pie, brush the butter on before baking and sprinkle large sugar granules for a pretty and delicious presentation.
Sweet pastries can achieve a shiny and crackled crust with a thin application of corn syrup mixed with warm water. Use equal parts corn syrup and water, and brush the mixture on your pastry before baking. This mixture can also help waterproof a crust that has been blind-baked. Once you've baked the pie or tart crust, brush the mixture on the bottom and sides of the crust to seal the crust from filling moisture.
Apricot or apple jelly, melted and applied with a pastry brush, gives a sheer shine and sweet finish to pastries. The nearly colourless jelly also helps toppings, such as seeds, small cookies or chocolate curls, adhere to your pastry. Apply the jelly after baking, or use on a blind-baked pie crust to help seal the crust from moisture.
A mixture of icing sugar and a small amount of water or milk, whisked until smooth, can be brushed or poured over the top of baked pastries for a sweet finish with a white, crackled look. Use a sugar glaze on Danishes, tea breads and cakes and cookies. Apply the glaze when the baked goods are barely warm or fully cooled so that the glaze doesn't melt off or soak into the pastries too much.