Bright field photomicrograph of an etched polished cross section of a modern mercury-amalgam gilded cast bronze. Typically the mercury gilding layer (top of image, ~5 µm thick) appears bright. Within the gilding layer it is common to see irregular lines that are residual outlines of the solidifying grains of gilding. The surface of the gilding is often smoother than seen in this modern example because extensive burnishing is carried out when a shiny finish is intended. The lower surface of the gilding layer can be uneven but well bonded to the substrate because heating causes some reaction of the gilding with the bronze. (Freer Department of Conservation and Scientific Research, Washington, DC, metallographic reference collection ME90069D).