Disturbing a glaze is one way to create a speckled layer in your work, this technique is demonstrated here. Using oil straight from the tube in Zinc White and Raw Umber, we skim a layer of this mixture onto half of a primed board to show the difference between working on an oil layer versus a simple primed surface. Once the oil is dry, wipe it down with a small amount of solvent, here we use Winsor & Newton’s Artists’ White Spirit. This will remove any oily residue and allow the glaze to slide on freely. The glaze we prepared is made from Prussian Blue mixed with a medium of 50:50 proportions of Linseed Stand Oil and White Spirit. The glaze appears differently on the two surfaces, being darker in the primed area and more transparent on the oil surface. That distinction is repeated when we disturb the glaze by flicking the 50:50 medium onto the surface with a hog hair brush. The glaze on the oiled side reveals a sharply speckled effect but the glaze on the primed side has a much softer response to the disturbance from the medium; both are interesting outcomes and you can choose which one best suits your work.