Why Cover Bread Dough as It Ferments? The short answer is – cover it to prevent it from drying out. And there is no good reason not to cover. But of course, there are things to consider. We all know to cover our dough so that it does not develop a dry skin on its surface which can give it an unpleasant look and texture. Some people use cloths, some use plastic wrap. There are advantages and disadvantages to both.