Thinking and Experiencing Techne: Making Azurite Pigment

by Dani Trew, Mariana Lima, Mia Spampinato, Elif Uluca, and Karen Morton.

As part of the V&A/RCA History of Design MA course, in the spring term students have the chance to explore early modern making techniques as a form of historical research through practice.  With the support of V&A curators and tutors, students have an opportunity to recreate early modern recipes, and reflect on practices of making, and the nature of artisan knowledge and skill.

Thinking and Experiencing Techne is a satellite project of the ‘Making and Knowing’ project based at Columbia University, in New York, and this year was also a cooperation with the V&A’s Robert H. Smith scholar in Residence Dr. Spike Bucklow, from the Hamilton Kerr Institute.

Students reflect on making Azurite pigment, the first of a series of experiments, in V&A blog posts which can be found here.

Azurite in the Early Modern by Dani Trew, film by Jekaterina Potasova and Mia Spampinato

Azurite has been used as a pigment since antiquity. In Cennino Cennini’s fifteenth century description of it in The Craftsman’s Handbook, he states that it ‘exists in and around the vein of silver’ and that it ‘occurs extensively in Germany’. This comment refers to the practice of harvesting the mineral from silver mines in Saxony from the twelfth century onwards. Azurite (Cu3(CO3)2(OH)2), is a copper carbonate which is chemically unstable and often undergoes a process of oxidization so that the surface becomes malachite (Cu(OH)2-CuCO3). While azurite is a deep blue, malachite is a bright green and when ground together a pale turquoise pigment is made. Cennini’s recipe for making azurite pigment, is essentially a guide to separating the azurite from the malachite, or as he calls it, bringing it ‘to perfection’.

Cennini tells the reader that one must grind the rock into a powder and add water but that this must be done ‘very moderately and lightly, because it is very scornful of the stone.’ This has been interpreted by D. V. Thompson as a warning against grinding the mineral too much, which would increase the ‘the reflecting surface and resultant scattering of light’, making the colour paler and less vibrant. When we carried out a reconstruction of the recipe, we experimented with grinding the rock to different degrees of fineness. It became clear that there is a perfect particle size which provides a vibrancy of colour while also allowing the malachite and azurite to disaggregate, it would, however, be difficult to convey the ideal size textually to someone who had never carried out the process before.

The separation of the two minerals in water relies on the malachite being hydrophilic and dissolving into the water while the azurite does not and sinks to the bottom. The term ‘hydrophillic’ is the modern scientific term for a chemical process which relies on a material being ‘water loving’ and the word and concept are rooted in the Aristotelian elemental philosophy of fire, air, water and earth. In the Aristotelian paradigm, the process of an earth element becoming water is a complimentary process which is both cold and gaseous. Within the medieval meaning system, these qualities also have gendered and spiritual meanings, with coldness associated with femininity and gas associated with the heavens. Similarly, as Spike Bucklow notes in The Riddle of the Image, copper (azurite is a copper carbonate) was also connected with femininity and Venus the goddess of love. As a result, azurite was widely used for depictions of the celestial realm and the Virgin Mary which can be seen in wooden sculptures, panel and canvas paintings during the Middle Ages and into the Renaissance. It should be noted, however, that while Azurite was celestial and feminine, it was decidedly terrestrial and prosaic in comparison to ultramarine which chemically, geographically, economically and spiritually denoted exotic lands and the entry into heaven.

The process of separating the azurite from the malachite in water is achieved through the rhythmic whirling and pouring off the liquid malachite into different containers without pouring away the azurite at the bottom. The repetition of the whirling motion and the tacit and embodied knowledge of when to start and stop pouring is both meditative, giving one insight into the physical and symbolic properties of the material, and also – as many of us found – deeply addictive.

Our understanding of the pigment, its application and its temporal behaviour was enhanced by close observation of fifteenth century polychromy from the V&A’s sculpture collection. We were able to observe how pigment was applied to the wooden carving in relation to other colours and on different figures, and how the pigments reacted to their surroundings over time. A patch of Azurite on the sculpture had, for example, turned black.  

Over the course of the day we learnt a great deal about the medieval meaning system and how this was connected to artisanal knowledge. Embodying the process of making Azurite pigment along with historically contextualising its application through object analysis made for an incredibly rich and stimulating experience.

 

Making Azurite Pigment by Mariana Lima, Mia Spampinato, Elif Uluca, and Karen Morton.

The azurite rocks we were working with. The green traces are malachite.
1. Break up the azurite with a hammer in a mortar.
2. Continue with pestle to achieve even finer grains; around 10 minutes – the quantity and therefore time depends on size of the original azurite piece. Large granules will give a brighter colour and smaller granules will increase the scattering of light and create a paler colour. Too large, however, and it will be difficult to fully separate the azurite from the malachite.
3. Transfer the powder to a ground glass plate (Cennini’s recipe suggests a porphyry slab) and continue grinding it with a ground glass muller to achieve a fine powder. You may need to use a brush to remove all the powder from the mortar interior.
4. Add a few drops of water at a time as you continue to grind and blend the mixture. Use small circular movements around the plate. Take care to constantly bring in the edge of the mixture to the middle so that all the grounds are evenly mixed. At this point you will feel the mixture trying to push against you. You may also see the lighter malachite particles beginning to separate from the mixture.
5. When the mixture is ’singing’ (a feel for this will develop with practice), scrape together in the centre of the slab with a palette knife (can substitute with a plastic card) and scrape off from the corner of the slab into a watch glass. Add a little more water to rinse off all into the watch glass.
6. Once in the watch glass, rub the mixture with your finger in circular movements to de-aggregate the mixture – separating the particles into different sizes.
7. Pour off the excess water into a new clean glass pot or watch glass. Pour out the water quickly, but not all water, in order separate from the pure sediment: azurite in the original receptacle. Be attentive: pure azurite will want to settle at the bottom of the watch glass.

 

8. Continue to wash the azurite: adding water and pouring, each time into a new clean receptacle. Using clean water leaves azurite behind more easily because more azurite is not being added (in ‘blue’ water azurite is in suspension from the previous pouring) and therefore separates more easily.
9. We also filtered the azurite in shells to replicate how this process would be done in the early modern period. Other minerals combined with the azurite will affect colour, for example, malachite creates a greener colour, sometimes this is not apparent until grinding commences. More coarsely ground azurite appears more blue because it is light absorbent, finely ground reflects light, but consider how well (or not) the coarsely ground azurite would mix with media for painting?
10. The final pigment, pure azurite blue.

References:

Cenninno Cennini, ‘The Craftman’s Handbook’, Translated by Daniel Varney Thompson (Dover: 1932)
Spike Bucklow, ‘The Riddle of the Image: The Secret Science of Medieval Art’, (Reaktion Books: London, 2014)

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