Oil painters traditionally applied paint in layers known as "glazes", a method also simply called "indirect painting". This method was first perfected through an adaptation of the egg tempera painting technique, and was applied by the Flemish painters in Northern Europe with pigments ground in linseed oil. More recently, this approach has been called the "mixed technique" or "mixed method". The first coat (the underpainting) is laid down, often painted with egg tempera or turpentine-thinned paint. This layer helps to "tone" the canvas and to cover the white of the gesso. Many artists use this layer to sketch out the composition. This first layer can be adjusted before proceeding further, an advantage over the "cartooning" method used in fresco technique. After this layer dries, the artist might then proceed by painting a "mosaic" of color swatches, working from darkest to lightest. The borders of the colors are blended together when the "mosaic" is completed, and then left to dry before applying details.