Why is it important to cover certain icings tightly?

Covering certain icings tightly is crucial to prevent drying out or crushing. When icing is exposed to air, it can form a crust or become hard, making it unsuitable for use on pastries and cakes. This is particularly true for buttercream and fondant, where maintaining a smooth texture and pliability is essential for achieving a professional finish on baked goods. If the icing dries out, it not only alters the texture but can also detract from the overall presentation and enjoyment of the dessert, leading to cracks or an unappealing appearance.

Properly covering the icing ensures that it remains workable and maintains its intended consistency until it is ready to be applied or used, thus preserving its quality and effectiveness in pastry decoration.