Impasto is a painting technique which involves applying paint very thickly to build up a texture of prominent brush or painting knife marks on a surface. The use of the paint is almost sculptural and can add a more expressive or simply attractive element to the artwork as can be seen in the image which is a section of 'Wheatfield Under Thunderclouds' by Van Gogh. Oil Paint is traditionally used for Impasto pieces due to its natural viscosity although Acrylic Paint can be used too usually with the addition of heavy body mediums.

The word, Impasto, derives from the Italian for ‘paste’ or ‘dough’ with the verb ‘impastare’ meaning ‘to knead’. Presumably either a reference to the marks in the paint surface being reminiscent of the finger marks in kneaded dough or simply referring to ‘pasting’ the paint onto the surface.