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Making Colour

Two films exploring how artists transform pigments into dazzling works of art and the science used to identify the raw ingredients of paint.

More from Making Colour (2 videos)

  • In painting, the colour purple was traditionally achieved by artists mixing red and blue pigments together. Different mixtures resulted in purples of varying intensities and shades.

    But how can the separate ingredients of a purple be identified?

    At the National Gallery Scientific Department a tiny sample of paint, usually taken from the edge or from underneath the frame of a picture, is immersed in resin, dried, and then polished to produce a cross-section.

    This cross-section can be examined at high magnification under a microscope.
    This sample clearly shows separate blue and red pigment particles. Other methods of examination tell us even more.

    This scanning electron microscope, coupled with an energy dispersive x-ray analyser, can determine the composition of the pigments. The blue pigment in this purple paint contains copper, identifying it as the mineral azurite. The red pigment contains aluminium, which is characteristic of what are known as ‘red lake’ pigments.

    The colour in red lake comes from the dyestuff in insects such as kermes or cochineal, or plants such as madder root. Analysing a red lake using high performance liquid chromatography can identify which of these materials were used. To understand the ways in which a colour could have been obtained, members of the Department use historical recipes to prepare pigments.
    This is a 19th century method for obtaining red lake from madder root.

    Red lake pigments are particularly prone to fading on exposure to light.
    In this portrait of a young princess by Jan Gossaert the blue pattern on the sleeves was originally purple. The red lake pigment Gossaert mixed with blue azurite has almost entirely faded and the original colour is now only visible at the edge, where the paint has been protected from light.

    The Scientific Department’s contribution to understanding the materials, behaviour and stability of colour helps conservators and curators not only understand how the paintings in the collection have changed over time,
    but also how best to preserve them for the future.

    Making Purple: The Science of Art

    Visit the National Gallery's Scientific Department to see how the blue and red pigments traditionally mixed to make purple paint are analysed and identified. The methods used range from state-of-the-art electron microscopy to recreating historic methods for obtaining pigments.

    This film accompanies the National Gallery exhibition 'Making Colour' (18 June - 7 September 2014).

    Visit the National Gallery's Scientific Department to see how the blue and red pigments traditionally mixed to make purple paint are analysed and identified. The methods used range from state-of-the-art electron microscopy to recreating historic methods for obtaining pigments.

    This film accompanies the National Gallery exhibition 'Making Colour' (18 June - 7 September 2014).

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    Making Purple: The Science of Art

    Movie
  • The appearance of a painted colour depends partly on the pigment, but also on the ingredients used to bind the paint together. Pigments mixed with oil produce a glossy finish. Pigments mixed with egg yolk, to make egg tempera paint, will have a flatter, matt appearance.

    Painting in tempera

    Pigments made from mineral clays, known as green earths, bound in egg tempera, were used by Italian artists from the 13-15th centuries as a base colour for flesh.

    These greens were used to suggest shadows, and model the shape of the face.

    Pinks, reds and white highlights were added on top.

    Tempera dries so quickly, that different colours can’t be easily blended on the painting surface. So artists used delicate hatching when applying the different colours.

    The very green skin tone of many Renaissance faces may be due to the layers of pink paint having faded, revealing more of the base layer than was intended.

    Painting in oil

    With oil paint, the pigment is bound in certain kinds of oil, often linseed or walnut, that dry to form a tough film. 

    Jan van Eyck was particularly famous for his skill at working in oil.

    Oil paint dries slowly and so can be manipulated on the picture surface.

    Some pigments are opaque, others can be used to make a translucent ‘glaze’.

    Glazes can be built up in layers to produce a deep, glossy colour that can imitate gleaming satins, costly wool, velvet and rich silk damask.

    Making Green: Tempera versus Oil

    Watch a painting demonstration to learn about the different properties of green pigments bound in egg tempera and those mixed with oil, and see how these were used to achieve very different effects in masterpieces from the National Gallery's collection.

    This film accompanies the National Gallery exhibition 'Making Colour' (18 June - 7 September 2014).

    Watch a painting demonstration to learn about the different properties of green pigments bound in egg tempera and those mixed with oil, and see how these were used to achieve very different effects in masterpieces from the National Gallery's collection.

    This film accompanies the National Gallery exhibition 'Making Colour' (18 June - 7 September 2014).

    Read More
     thumbnail02:19

    Making Green: Tempera versus Oil

    Movie
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