During my 24 years of teaching oil painting I noticed that it’s difficult for the beginners to grasp the idea of oil colors transparency. In this blog I will try to clarify it in the simplest terms.

You may categorize oil paints as transparent, semitransparent or opaque. Notice that the pigments (colors) that are considered opaque will be somewhat transparent if spread in very thin layers.

Transparency of oil paints allowed artists to develop several useful techniques such as glazing:

• Glaze is a very thin layer of transparent color spread over a dry layer of underpainting.
• Underpainting is a monochrome basic layer executed using only grey values, like black and white or green and white, etc... After this is completely dry, a glaze is applied and a thin layer of transparent oil color is laid over the gray values.
• Glazing produces different and unique effect that cannot be achieved by applying the paint directly into a white canvas.

Glazes can be used for additional effects:

• Darkening of some parts of the picture without repainting it.
• Adding saturation (higher chroma).
  
• Desaturating (lowering chroma) certain parts of the painting without loosing the details.
• Glazing the whole painting (after it’s completely dry to touch).
  

Keep in mind, most of the oil paints are transparent or semitransparent.