lf a painting done in oils or acrylics becomes overworked, or clogged with too much paint, the excess can be removed by means of a technique known as ‘tonking’, which is done by blotting with a sheet of absorbent paper (such as newspaper or kitchen towel) on the surface of the canvas, gently pressing the paper onto the wet paint and then lifting it. The excess paint will be absorbed by the newspaper sheet, thus leaving behind a workable surface. The technique was invented by Professor Henry Tonks (1862-1937) of the Slade School of Art.