What happens is that in each clump you've got the gelatinization of starches, which happens very quickly at the surface of the clump and it kind of forms a protective skin around this dry hunk of flour.
The skin is forming because of proteins, just like if you cook milk or anything else that's got a coagulant protein in it.
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.
