What we are referring to as “glaze oil painting” is sometimes called “indirect painting” or Renaissance oil techniques” or “traditional oil painting”. This process is known for the remarkable luminosity and illusion of depth.
First, let’s talk about “direct” or “a la prima” painting. These modern painting techniques, revolutionized painting methods during the Impressionist era, and include most mainstream painting techniques that have occurred since that time. Direct painting involves putting colour that has been premixed on a palette, directly on the paint surface. If the artist wants orange, he or she will mix it up on the palette or get it from a tube and place it where it belongs.
“Glaze oil painting”, by contrast is “indirect“. These techniques are old and stem from the Early Renaissance. The remarkably different results are achieved by building colour in incremental steps - in layers - by first laying foundational values and colours. These steps are called sometimes called “grisaille” and “velatura” and they create light structure that provides light and lack of light behind the final layers. They are then followed with layers through which light can penetrate. Light moves in and out of the paint surface, refracting in and around it, and in the process, it fully illuminates suspended colour particles. This makes colours literally glow. This is known as “indirect” as opposed to “direct”. Colour effects do not come in one direct step, but by a weaving path of steps that push the light and the colour into a magical balance of perfect luminosity. Light does just reflect directly from the surface of the paint, but in very complex ways indirect ways, through the many layers of paint. This is “complex colour”. And it is spectacular.