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Everything You Need To Know About Pigments

Updated: Jan 5

Pigments are one of the components of acrylic and oil paints and are the ones responsible for the colour of the paints. Here a little overview.


Pigments

Image by Alexander Grey


What are pigments

Pigments are organic or inorganic, no water-soluble colouring powder that together with a binding medium (oil, wax or other substances) are used to produce paints or coloured pencils. Due to their ability to absorb a particular wavelengths of visible and change the reflected light they are also called absorption pigments.

In nature they are found as inorganic compounds that during a manufacturing process are reduced to a powder form to be used in producing paints.


Organic vs inorganic pigments

The first distinction can be made between organic and inorganic pigments.


Organic pigments can have a plant or animal origin and contain carbon compounds. Nowadays, they are being replaced by synthetic versions and the best-selling ones are the so-called "AZO pigments". These insoluble pigments are mainly used in artificial colours to produce yellow to red hues because of their brightness and lightfastness.

Examples of organic pigments are AZO pigments such as brilliant yellow and permanent red, or phthalocyanine blue.


Inorganic pigments have a mineral origin, do not contain carbon compounds and can be either natural or synthetic. Natural inorganic pigments are pigments produced by grinding and drying minerals and earths, while synthetic inorganic pigments are industrially produced and are used to give the colour a metallic effect.

Examples are

  1. Arsenic pigments: Auripigment, Realgar, Schweinfurt Green.

  2. Lead pigments: Lead red lead, lead tin yellow, lead white, chrome yellow, Naples yellow

  3. Cadmium pigments: cadmium yellow, cadmium red, cadmium orange

  4. Cobalt pigments: cobalt blue, cobalt coline blue, cobalt turquoise, cobalt violet, Rinmans green, smalte

  5. Iron pigments: yellow ochre, red ochre, iron oxide black

  6. Copper pigments: Egyptian blue, azurite, Bremer blue, verdigris, malachite

  7. Manganese pigments: Manganese blue, manganese black, manganese violet


Effect pigments

Moreover, based on the produced effect, pigments can be classified in

  • metallic pigments

  • interference pigments

  • Luminous pigments (neon pigments, fluorescent pigments)


Metallic pigments, usually identified with C.I. Pigment Metal in the Colour Index, are very small brass or aluminium flakes and the effect depends on the orientation of the surface: the flatter the surface is, the darker the metallic effect will be.


Interference pigments are usually MICA based pigments that are coated with one or more extremely thin, uniform and high refracted layers. The interference effect depends primarily by the chosen parameter for the coating layers which enable the viewer to see different colours depending on his viewing angle. This pigment category is the base for the pearlescent or interference acrylic paints.


Luminous pigments are pigments that are able to absorb light and are either brighter on a daylight (neon) or can glow in the dark thanks to exposure to UV-light (fluorescent colours). Another kind of luminous pigments are phosphorescent pigments, which can glow in the dark without being exposed to UV-light.


If you want to have more information about the existing pigments and their characteristics the most important source is the “Colour of Art Pigment Database” .


In this database pigments are identified with a P (for “pigment”) or an N (for “Natural”), the hue of the pigment itself and a number, which represents the assigned progressive number given when the pigment is added to the index:


  • PW: Pigment White (W)

  • PY: Pigment Yellow (Y)

  • PO: Pigment Orange (O)

  • PR: Pigment Red (R)

  • PV: Pigment Violet (V)

  • PB: Pigment Blue (B)

  • PBr: Pigment Brown (Br)

  • PBk: Pigment Black (Bk)


Furthermore you will get for each pigment information about their names and their characteristics in terms of marketing name, opacity, lightfastness, colour shade tendency.


Finally, if you are curious and you want to learn more about the topic, I advise you to have a look to the wonderful series “Pigment Colour Index” by Evie Hatch.


In this series she explains how the “Color of Art Pigment Database” works and gives you an interesting overview about each colour group separately.



Are pigments toxic?

Pigments are the basis of all paints, and have been used for millennia. Throughout history they have been obtained from both organic raw materials such as ground earth or clay (examples of early pigments are minerals limonite and hematite (red ochre, yellow ochre and umber), charcoal from the fire (carbon black), burnt bones (bone black), white from grounded calcite (lime white)), and inorganic raw materials such as Iron oxide pigments (red ochre, yellow ochre and umber), Lead pigments (lead white and red lead), and mercury sulfide mineral (Vermilion).

Started from the 19th century, pigments became the result of chemical trials and often they were produced using highly toxic metals such as chrome (for yellow, orange, green), cobalt (for yellow, violet, blue), cadmium (for yellow, orange, red), manganese, mercury (vermilion red) and zinc. The most deathly and poisoning pigments used in art were Lead White (PW1, containing lead), Scheele Green (PG21, containing arsenic), and Radium Orange.

Today, Even though pigments in their fine-particulate powder form remain a problem for the environment (they are not bio-degradable), they are (mostly) safe for human, if used properly. In commerce there are still toxic paints or dangerous pigments but the risks can be minimized by following the instructions or wearing safety equipment while using them. For example, if you use potentially dangerous pigments to create your own paints, you should always wear a mask and gloves, in order to avoid any direct contact with them: even though the one time contact with them can be without consequences, the cumulative effect in the long run can lead to serious illnesses.

In addition there is a tendency in the manufacturing of art supplies to substitute dangerous pigments with safer alternative (for example cadmium free acrylics by Liquitex Heavy Body). Here a very interesting article about this topic.


Conclusions

This was your short overview to try to learn a little bit more about one of the based ingredients of our acrylic paints.

I hope you enjoyed and found it useful to learn something more about them (like I did).

Thank you for reading. If you like the post, feel free to leave a like, a comment and don’t forget to follow my blog, my Instagram, my Threads and share the content on your social media.


Have a colourful and creative day.


Laura


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