[Azurite grinding and lake making]

Name: Nina Elizondo-Garza
Date and Time:

2017.[October].[10], [18]:[00][pm]

Location: Lab
Subject: Grinding and levigating azurite

To prepare for this exercise we read up on the significance of blue paint in the early modern period. Azurite was apparently highly significant, and quite valuable, but not as valuable as the ultramarine pigment which results from lapis lazuli. Azurite degrades into malachite over time, which means that most blocks of azurite will have some impurities we need to filter out before we can make a nice blue pigment from it.

There were two grades of azurite for us to use -- Carl and I got the lower quality one (which means it had more malachite impurities).


We crushed up the azurite chunks in a mortar; I had to smash them pretty vigorously to get them to be fine enough to grind.


It was a bad auditory experience (grinding rock on a marble mortar). We started to get the feeling it was ready to be levigated once it felt softer, siltier --with no noticeable chunks of rock and an even texture.



Once it was fine enough, we spread it on the plate which would be our makeshift glass slab and incorporated it with a few drops of distilled water at a time to start mulling. The most valuable pigment of all would be a clear, clean blue. As evidenced by this current color,we were quite far from that standard. As we ground it, it was also a bad auditory experience. We were grinding fine-grained rock on glass. It was a gritty noise. However, as we got closer to a finger grind, the sound became much softer, less grating --almost like a hiss. We alternated between mulling it and scraping the ground stone into a pile at the center of the glass plate to begin mulling again. Once we reached that 'soft hiss' level it was time to levigate --filter out the malachite impurities to get the blue. Malachite is 'lighter' than the blue azurite, so it floats to the top while the azurite sits on the bottom. In this way we can extract the azurite lake.



Here is the first mix of pigment and distilled water, in our handy mussel shell portion size. I waited for the dust to settle and poured the water out onto another shell to leave the settled pigment on the bottom.



I was very excited to start seeing the faintest trace of BLUE at the bottom of all that green. At this point I developed a good strategy for emptying the shells of water without disturbing the pigment: using the surface tension of the water, Iightly tipped the shell back and forth to settle the pigment on the narrow side of the shell while the water I would pour out pooled closer to the edge; this made it easier to pour out without accidentally losing any of the blue.


I was excited because I thought I had finished; that this would be my peak blue. I was mistaken.



Eventually I switched to using this clam (?) white-based shell as my "home shell" (i.e., the shell I would try to collect my pigment in) and it made it much easier to see what I was doing and what color I should be focusing on.



My final results. Both shells are full of blue pigment from that first mussel-shell full of watery pigment (somehow!! I ended up with a lot of good blue). On the card, I marked the color of the water each time I added some to the ground stone, after I let the mixture settle before 'filtering' it again. As you can see, it became clearer as I filtered out the malachite-y water and was left with the purer sediment. The blue pre-lake felt nice to the touch; it felt like fine silt. There was no binding agent, however, so this was pure powder -it had no holding power. Before it can be made into a pigment we need to grind it again.

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Name: Nina Elizondo-Garza
Date and Time:

2017.[October].[23], [13]:[00][pm]

Location: Lab
Subject: Grinding the azurite again

Our azurite had sat neglected for a few days, but now it was time to grind it again, which was apparently necessary before it could be made into a pigment. Scraping the lake out of the shells made it much more vivid and blue, though we had to be careful when scraping as to not get bits of shell in the mixture. Using a plastic palette knife minimized the risk of this happening, and also was easier to use to handle the lake.






An infamous rumor about azurite is that if you over-grind it, it will "die" and lose it's color. According to our expert maker Jo Kirby, that's not true, and it will stay blue. Sophie Pitman and I decided to kill some azurite to see what would happen. We mulled it on a glass slab, using distilled water applied with a pipette.


We ground this azurite for around thirty-forty minutes, and it is clear that the color is much paler than what would be expected from dry azurite powder in the above photographs.


On the left is the over-ground azurite; note the white streaks on the metal slab. We weren't sure what those were? Possibly silica residue from the stone itself as it ground up. On the right is some barely mulled azurite powder. As I was grinding this new batch, I noticed that it did indeed start to lose its color very quickly after beginning to mull. As a result I chose to mull it very lightly as to maintain a big difference between the two blues, and to check if that light level of mulling would be enough for it to paint well when made into a paint.


On the left: the over-ground azurite (still wet)
Middle: The barely ground azurite (still wet)
Right: azurite powder that has only been mulled once, and then was levigated. It's what I ended up with in my shells. I wanted to leave a bit of it un-mulled so we could compare the colors to the original product.

The lake in the middle jar has clearly retained a much brighter blue than the over-ground one, but it remains to be seen if it will paint well. Perhaps this azurite which I levigated is deceptive; it looks blue in un-mulled powder form but once time comes to prepare it to become a pigment it rapidly loses its color/quality?

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Name: (Also the name of your working partner)
Date and Time:

2016.[Month].[Day], [hh]:[mm][am/pm]

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ASPECTS TO KEEP IN MIND WHEN MAKING FIELD NOTES

• note time
• note (changing) conditions in the room
• note temperature of ingredients to be processed (e.g. cold from fridge, room temperature etc.)
• document materials, equipment, and processes in writing and with photographs
• notes on ingredients and equipment (where did you get them? issues of authenticity)
• note precisely the scales and temperatures you used (please indicate how you interpreted imprecise recipe instruction)
• see also our informal template for recipe reconstructions

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