You know, [skin] happens at the gravy boat stage - right? - or this happens when you're trying to keep it warm. So the way that I avoid this is I keep my gravy - the second it's done, I put it in a thermos, which will keep it hot and will prevent air from getting to the surface. And I keep it there till the last moment. The last thing that goes out to the table is the gravy, and I pour it out of the thermos and immediately move it in.
Alton BrownA meringue is really nothing but a foam. And what is a foam after all, but a big collection of bubbles? And what's a bubble? It's basically a very flimsy little latticework of proteins draped with water. We add sugar to this structure, which strengthens it. But things can, and do, go wrong.
Alton Brown