Organic and Inorganic Pigments
Before we get into the sciency bits, it’s probably worth asking the question: why it is necessary to learn more about what makes up the paint we use?
While having an awareness of your materials may not automatically make you a great painter, having a understanding of the what they are made of will allow you to make informed decisions throughout the painting process. As a result, this can help you to achieve what you set out to achieve with each painting. This is what many artists, such as Sir Joshua Reynolds, think constitutes excellence in art:
“The excellence of every art must consist in the complete accomplishment of its purpose”
Each pigment has unique characteristics; such as opacity, transparency, and lightfastness, which significantly impact the final appearance of a painting. My focus in this blog is on how these characteristics are impacted by being organic or inorganic.
Organic pigments are manufactured from substances that contain carbon chains and rings. Put simply, they are made from something that was once living.
Carbon-based pigments are derived from animals, vegetables or synthetic organic chemistry. While traditional pigments were typically created using vegetation and animal products, the majority of modern ones are created through synthetic organic chemistry.
Crimson, Purple Lake, and Carmine are all derived from insects. From the vegetable world, we’ve got Indigo, Gamboge, and The Madders.
We also have synthetic organic pigments which are made from organic matter in a laboratory. Most of these will be petrololeum or coal based, but still contain carbon chains and rings.
Pthalocyanines, Quinacidrones, Dioxazenes, and Napthols are all examples of synthetic organic pigments that are made from petroleum and coal.
Inorganic pigments are not based on carbon chains and rings. Instead, they consist of dry, ground minerals, usually metals and metallic salts.
Because of their composition, inorganic pigments are usually more opaque and less soluble than organic pigments.
They’re like tiny, opaque rocks and integrate well with mediums, allowing a high pigment load.
Earth Colors are all examples of inorganic pigments. Painters will have been using the Earth pigments for thousands of years, as they were so readily available. Luckily for us, due to their ligthfastness, many old paintings have survived to this day.
Cadmiums, Cobalts, Lead and the other heavy metals are also all examples of inorganic pigments. They are extremely lightfast and have produced some of the extremely chromatic paints that we use today.
However, using these metals does have a downside and that is their toxicity. The heavy metals most commonly associated with poisoning humans are Lead, Mercury, Arsenic and Cadmium.
Organic and inorganic pigments is just a small part of the big but interesting topic of pigments. If you are interested in learning more about pigments in general, I recommend reading Todd Casey’s, The Oil Painter’s Colour Handbook.