Investigation topic 3: The chemistry of Aboriginal and Torres Strait Islander peoples’ practices
Throughout history, people all over the world have hypothesised, experimented, made empirical observations, gathered evidence, recognised patterns, verified through repetition, and made inferences and predictions to help them to make sense of the world around them and their place within it. Recent research and discussion have confirmed many Aboriginal and Torres Strait Islander groups use the environment and its resources to solve the challenges they face in the different Australian climates in ways that are more sustainable than similar materials produced in Western society. Their solutions can be explained by a variety of organic and non-organic chemical processes.
Questions that may be explored in this investigation include:
· How do Aboriginal and Torres Islander peoples utilise animal fats, calcination and plant pigments to vary the properties of the paints they make, and how does this compare to Western paint production processes and materials?
Pigments are the basis of all paints, and have been used for millennia. They are ground colored material. Early pigments were simply as ground earth or clay, and were made into paint with spit or fat. Modern pigments are often sophisticated masterpieces of chemical engineering.
Until paint was produced commercially during the Industrial Revolution (circa 1800), painters had to make their own paints by grinding pigment into oil. The paint would harden and would have to be made fresh each day. Paint consists of small grains of pigment suspended in oil. Although it appears smooth to the naked eye, on a microscopic level, particles of pigment are suspended in oil, as fruit in a Jello mold.
Oil paints do not "dry" by evaporation (as do watercolor paints); rather they harden through chemical reaction, as a Jello sets. Contact with the air causes oils to oxidize and to crosslink. The paint sets and hardens over time. Paints of different pigments dry at different rates. Charcoal black retards the drying (creating a slow-drying paint); ochre accelerates the drying (producing a quick-drying paint).
Pigments in acrylics. (n.d.). Webexhibits. https://www.webexhibits.org/pigments/intro/acrylic.html
Pigment catalogue (image below). Learn about the history, manufacture, and technical details of the following pigments, all of which are some of the most historically important in art.
Many of the paints that have long been used, and continue to be used, by Aboriginal and Torres Strait Islander Peoples contain pigments extracted from minerals. The mineral pigments that are selected for the manufacture of paint are insoluble in water to ensure that the prepared paint cannot easily be removed from a surface, even when exposed to rain, groundwater or perspiration. The manufacture of paint begins with the mining of ochre to obtain the natural, raw pigment, followed by the cracking, crushing and grinding of the ore into a uniform powder. Minerals that are used as pigments are selected based on the colour they impart to the paint and include: kaolin or huntite for white; ochres (ferric oxide) for yellow, red and orange; manganese oxide for black; haematite for red and limonite for yellow. Paint is prepared by combining the powdered pigments with a binder, the liquid component that allows the paint to be applied as a film onto a surface.
Aboriginal Peoples understand the physical properties of the mineral pigments that they use in paints, such as durability and stability. The selection and quality of materials, and changes in climatic conditions, can impact the longevity of a painting.
Pigments for paint can also be extracted from plant material. Aboriginal and Torres Strait Islander Peoples understand the physical properties offered by biological pigments, such as stability and solubility, and use this knowledge to select plant rather than mineral material for paint.
Binders
Binders are selected based on the properties they confer to the paint, including adhesiveness, viscosity or thickness and the finishing effect. Binders can be derived from carbohydrate (honey, orchid sap), protein (egg, blood) or lipid (oils, fats). Binders can be used to control the painting style; viscous paints are used for clear, defined lines and thinner paints produce a translucent effect.
The Anindilyakwa Peoples of Groote Eylandt use the sap of the native orchid as a binder in bark painting due to its physical properties of adhesion and viscosity. Before the sap is added, the ground pigment is mixed into a paste with water. Then, the stem of the orchid is used to incorporate the mucoid orchid secretion. The viscosity of paint can be controlled by the careful addition of water to the paint mixture, until the desired consistency is achieved. Read the whole article.
The Australian curriculum. (n.d.). The Australian Curriculum (Version 8.4). https://shorturl.at/oBOP6
Aboriginal and Torres Strait Islander Peoples’ scientific knowledge of the properties of natural materials has long informed their selection of natural materials to make paint
It is important to understand that Aboriginal and Torres Strait Islander Peoples’ scientific knowledge of the properties of natural materials has long informed, and continues to inform, the careful selection of natural materials to manufacture paint.
For millennia, Aboriginal and Torres Strait Islander Peoples have prepared pigments for paint using natural resources, including mineral and plant materials. Understanding the physical properties of resources informs the careful selection of natural materials to ensure that the materials are fit for purpose. Paints are further enhanced by adding other natural materials to act as binders and fixatives to preserve paintings or to achieve desired styles, such as sharp, defined edges. Read more at the source.
The Australian curriculum. (n.d.). The Australian Curriculum (Version 8.4). https://www.australiancurriculum.edu.au/TeacherBackgroundInfo?id=56646
This workshop brought together 15 conservators from big museums and galleries across Australia and over 30 Aboriginal artists from Art Centres in Arnhem Land.
This workshop brought together 15 conservators from big museums and galleries across Australia and over 30 Aboriginal artists from Art Centres in Arnhem Land. Together, they shared their knowledge on the harvesting, production and conservation of cultural objects made from barks, Pendanus, dyes and ochres. This Inspiring Australia initiative is supported by the Australian Government Department of Industry, Innovation, Science, Research and Tertiary Education.
https://vimeo.com/72787939?embedded=true&source=video_title&owner=1736739
Master weaver and colour dyer Laŋani Marika, the most senior elder of the Rirratjiŋu clan, imparts her colour knowledge to the generations of tomorrow in this 6 piece video installation by The Mulka Project of Northeast Arnhem Land.
https://vimeo.com/mulka
Master weaver and colour dyer Laŋani Marika, the most senior elder of the Rirratjiŋu clan, imparts her colour knowledge to the generations of tomorrow. See more videos about how colours are made at The Mulka Project.
Pigment characterisation in Australian rock art: a review of modern instrumental methods of analysis
Ochre is a mixture of natural minerals including iron oxide and clays [7]. Iron oxides, including haematite [Fe2O3] and goethite [FeOOH], in their different forms and combined with other minerals are responsible for the characteristic red, yellow and orange colours associated with this pigment source. Kaolinite [Al2Si2O5(OH)4], huntite [CaMg3(CO3)4], gypsum [CaSO4·2H2O] and/or calcite [CaCO3], for example, are minerals present in Australian white pigments. The specific compositions of such minerals vary by source location.
Pigment characterisation in Australian rock art: A review of modern instrumental methods of analysis. (2017, March 13). SpringerOpen. https://heritagesciencejournal.springeropen.com/articles/10.1186/s40494-017-0123-8
Chemical reactions employed in the production of new substances
Investigating chemical reactions employed by Aboriginal and Torres Strait Islander Peoples in the production of substances such as quicklime, plaster, pigments, acids, salts and ethanol
Chemical processes and subsequent products developed and used by Aboriginal and Torres Strait Islander peoples prior to European contact
Below are four documented chemical processes and subsequent products developed and used by Aboriginal and Torres Strait Islander peoples prior to European contact:
1.calcination as used to produce plaster (calcium sulfate) and pigments such as iron oxide
2.pyrolysis used in the production of charcoal, quicklime, pyrolignious acid and salts
3.fermentation in the production of ethanol
4.combustion in the production of heat and light
Further resources:
Babayemi, J. O., Dauda, K. T., Nwude, D. O., & Kayode, A. A. A. (2010). Evaluation of the composition and chemistry of ash and potash
from various plant materials: A review. Journal of Applied Sciences, 10 (16), 1820-1824.
Backhouse, J. (1843). A narrative of a visit to the Australian colonies. London: Hamilton, Adams, and Co.
Bates, D. M. (1929, July 4). Aboriginal Perth. Western Mail. Retrieved from http://nla.gov.au/nla.news-article38887581
Clarke, P. A. (2012). Australian plants as Aboriginal Tools. Kenthurst, NSW: Rosenberg.
Douma, M. (Curator). (2008). Carbon black: How carbon black is made. In Pigments Through the Ages. Retrieved from http://www.webexhibits.org/pigments/indiv/recipe/charcoal.htm 92
The difference between the use of natural ochre used in Aboriginal art and acrylic paint
There is a vast difference between Aboriginal Paintings produced from ochre as compared to the modern medium form of acrylic paints.
Ochre used in Aboriginal paintings were usually dug or mined from places with a kind of soft colourful stone which is completely natural. There are a variety of colours that can be extracted and then mixed with other pigments to produce other colours/hues much like the way we mix acrylic colours to form other pigments. Expert artists mix the ochres to create colours that range from reds, varying shades of brown, greys, sandy yellows, soft pinks, whites, purples and greens.
Linklater, S. (2022, May 19). Difference between natural ochre & acrylic paint in Aboriginal art. Artlandish Aboriginal Art. https://www.aboriginal-art-australia.com/aboriginal-art-library/ochre-acrylic-differences/
Indigenous paint sources and composition
Ochre is the name given to a family of natural earth pigments containing iron oxide. The name is also loosely associated with any pigment that may be derived from basic processing by the crushing or grinding of minerals or mineral aggregate.
Fixatives are often employed in the production of ochre based paints. These enable a pigment to adhere to a surface, and also act to further the longevity of the final artwork. Fixatives and binders have historically included plant resins and gums, orchid sap, honey, egg, blood, saliva, and animal fat. Contemporary binders include refined ‘Gum Arabic’, and P.V.A glue.
Read about the different types of ochre and how they're used as paint at the source.
Koorihistory.com. (2016, May 9). Earth pigments: Did Aboriginal people use blue ochre? Koori History - Aboriginal History of South Eastern Australia. https://koorihistory.com/earth-pigments-ochre/
(n.d.). NSW Resources Regulator. https://www.resourcesregulator.nsw.gov.au/sites/default/files/2022-11/ironoxide.pdf
Pigments and palettes from the past - science of Indigenous art
Some Indigenous paintings have lasted thousands of years … so what is it about the pigments that make them so long-lasting? Carolien Coenen/Flickr, CC BY-NC-ND
We examine the chemistry and techniques behind perhaps the most iconic element of Indigenous life: rock art. Pigments survive depending on their stability to climatic variations and then ultimately due to their ability to intimately bond with the rock.
Thorn, A. (2014, December 25). Pigments and palettes from the past – science of Indigenous art. The Conversation. https://theconversation.com/pigments-and-palettes-from-the-past-science-of-indigenous-art-35604
Microelemental characterisation of Aboriginal Australian natural Fe oxide pigments
This manuscript presents the first comprehensive microcharacterisation of Fe oxide minerals used in Aboriginal Australian mineral pigments. The combination of X-ray fluorescence microscopy (XFM) and light microscopy provides a broad characterisation as well as the ability to spatially match visual observation with elemental composition. A novel method for casting pigment samples in a pattern on a slide was used for consistent elemental mapping. Semiquantitative bulk data was also collected and compared to the microscopic and microelemental data. These analyses demonstrate the ability to document the variability in ochre pigments in Australia, as well as which elements drive the variation within and between ochre source locations.
Microelemental characterisation of Aboriginal Australian natural FE oxide pigments. (n.d.). RSC Publishing Home – Chemical Science Journals, Books and Databases. https://pubs.rsc.org/en/content/articlelanding/2015/AY/C5AY01547B
The Chemistry of Art
What is acrylic paint?
Acrylic paint is a modern invention that allows artists to create bold paintings with strong colours, while also mimicking the qualities of other media. It is an appealing medium because of its versatility.
What is Acrylic?
Acrylic paint consists of pigment suspended in a binder of acrylic polymer emulsion. Water is the vehicle for the acrylic polymer emulsion.
Read more about acrylic paint here, and see the stages of an acrylic painting step by step. This resource also includes 'mixing paint', 'sketch and gesso', 'underpainting', 'lights and shadows', 'adding colour', 'details', 'layering and glazing', and 'finishing the painting'.
What is oil paint?
Oil paints are comprised of pigments ground with oils, most commonly linseed oil. The mixture of pigment and oil is then dried to the consistency of butter, causing the applied paint to dry slowly without changes in color intensity. When oil oxidizes, it forms a solid film that binds the pigments, allowing oil paintings to be enjoyed for hundreds of years.
Pigments in acrylics. (n.d.). Webexhibits. https://www.webexhibits.org/pigments/intro/acrylic.html
