Millais brushed a thin coat of varnish over his painting of Ophelia. Varnish gives an even gloss to the surface of the painting and protects it from dirt, dust and surface damage. This type of varnish goes yellow with age.
Millais used a porcelain palette rather than a wooden palette because it was smoother and easier to clean and he could keep his colours pure. He also chose an oval shaped palette rather than a rectangular one. Oval palettes were designed to be held and rectangular palettes would have been placed on a table.