Gravy problems, diagnosed

Try to lift the fat with a spoon. If a distinct golden layer sits on top and the gravy underneath is smooth, you simply have excess rendered fat and can skim it. If the gravy is oily and thin throughout, with fat dispersed across the surface, the sauce may have broken and needs to be re-emulsified or re-thickened rather than only skimmed.

Lumpy gravy usually comes from adding stock too fast, starting with a patchy roux, adding dry flour directly to hot liquid, insufficient whisking, or reheating a cold starch-thickened gravy too aggressively.

Thin gravy usually needs more simmering, less total liquid, enough roux, a true thickening temperature, or better control of late stock and drippings additions.