Verdigris

Name: Njeri Ndungu
Date and Time:

2016.January.25, 5:00 pm

Location: Ndungu Home
Subject: Initial set-up of experiment

Purpose
Practical purpose: Produce verdigris (copper acetate) pigment, historically used to green/blue paint.
Learning purpose: To gain practice in the laboratory environment, considering the safety and procedural protocols required for successful experiment. Also consider which substitutions with contemporary equivalents can be made during historical reconstruction, balancing fidelity to recipe with safety and modern day availability.

Recipe
Merrywether – 418

84. To make verdigris
Take plates of copper, and suspend them over the vapour of strong vinegar in a jar covered with clay and well closed, so as to be air tight; then put the jar into the dung or refuse of grapes, in the time of the vintage, for the space of 15 days, when you must open the jar, and you will fin the verdigris adhering to those plates. Scrape it away, and return it as before.

Observations:

Day 1:

The copper plate was suspended with string inside of a mason jar containing about 5ml of 20% acetic acid as shown below.



During transportation, the acid had begun to evaporate within the jar, condensing on the inside walls and move around inside the jar coating the sides of the jar. The plate was suspended high in the jar to avoid coming in contact with the sides of the plate for this purpose. The jar was placed on a high shelf with temperatures ranging between 22- 27 degrees C. The shelf is open to indirect sunlight. There is minimal moisture accessible. Perhaps would be better to have smooth mason jar for easier observations.

---

Name: Njeri Ndungu
Date and Time:

2016.January.26, 11:00 am

Location: Ndungu Home
Subject: Verdigris production

After about 16 hours the copper plate had turned a greenish blue color. The texture of the plate seemed essentially the same, the green color following the dents and folds of the sheet. It did provide a matte/ rough texture with the overall color change. The color change appears to have occurred evenly over the entire plate, perhaps only slightly less has formed at the top of the plate where the copper color appears to peak through. There is no change in the color or features of the acetic acid, the acid that had condensed onto the sides of the jar have now collected back at the bottom.

---

Name: Njeri Ndungu
Date and Time:

2016.January.27, 8:36 pm

Location:Ndungu Home
Subject: Verdigris Production

There appears to be no change or development to the copper plate. It is still the same greenish blue color and the acid is still clear.

---

Name: Njeri Ndungu
Date and Time:

2016.January.28, 7:56 pm

Location: Ndungu Home
Subject: Verdigris Production

There appears to be no change or development to the copper plate. It is still the same greenish blue color and the acid is still clear.

---

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

2016.January.29, 10:56 pm

Location:
Subject:


There appears to be no change to the copper plate. Perhaps this is due to the fact that I have decided to bypass the step requiring the jar be put in “dung or grape waste.” I interpret this to mean kept warm. I have wrapped the jar in an old scarf and placed it in a dark, dry corner for the weekend.

---

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

2016.January.31, 11:10 am

Location:
Subject:


The warming apparatus appeared to have been a bit too successful. The volatile 20% acetic acid has warmed and evaporated inside of the jar, condensing on the walls of the jar and the copper plate. The condensed acid then dripped from the plate into the acid at the bottom of the jar, taking some of the vertigris with it and tinting the acid blue. The jar was removed from the warming apparatus and placed back on the original shelf.

---

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

2016.February.2, 6:04 pm

Location:
Subject:

There appears to be little change to the system. The copper plate appears to be a slightly darker blue color, but this may simply be due to the fact that it is now wet and saturated with the acetic acid.

---

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

2016.February.3-7, 11:00 am

Location:
Subject:

There appears to be little to no change to the system. The acetic acid on the walls of the jar has begun to condense and collect back at the bottom of the jar.

---

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

2016.February.8, 9:00am

Location:
Subject:

There appear to be little to no change in the system. Assessing the system once more before preparing for transportation has shown that the verdigris from the bottom of the plate on one side has been completely stripped off of the plate and the copper plate has been exposed beneath it. The string suspending the copper plate has tinted blue.

---

Name: Njeri Ndungu, Cleo Nisse, Ann-Sophie Barwich
Date and Time:

2016.February. 8, 1:00 pm

Location: Chandler 260
Subject: Paint production

Purpose
Harvest verdigris pigment and paint gesso board

Observations:

Trial 0: Cleo and Ann Sophie

• Remove copper plate from jar
• Splashed acetic acid onto the corner, prevented it from forming

• Scrape by pushing down and using bend quality of the palette knife
  • o Lateral, shallow motion, scrape movement, not straight down into the plate

• Grooves in plate prevent from cleanly scraping
• Ann- Sophie used a sawing motion, “doesn’t want to sneeze”
• Different color pigment as they scrape off
  • o Top layer appears a bit darker than the underlayers of the verdigris

Trial 1:

• [[Method Observation: I don't take as many photos when I am doing the experiment myself. I will try again taking voice recorded notes and more pictures. See Below]]
• I used shallow, shorter motions with the tip of my palette knife because slightly harder to remove since had been wet it appeared
• Condensed liquid on plate seemed to put the verdigris back into solution while scraping
  • o The solution then dried fairly quickly
• Scraped the sheet for about 5 minutes
• Transferred the pigments into a small container, labeled Njeri Verdigris 20% acetic acid, 2/8/16
• Left about two palette tips of pigment on plate
• Added about a drop and a half of walnut stand oil onto the glass sheet
• Ground and mix pigment on glass with white mortar – appears to be slightly porous and absorb the pigment and oil
• Quite thin color, thick pigments evident on surface, creates a bright blue color tinted only slightly green (teal)
• Mix and grind for 3 seconds
• Took a break (30 seconds) while Ann-Sophie worked
• Continue grinding for about 90 seconds, coming back to grinding after a minute and a half, the oil appears to have thickened or rather solidified a bit. Takes a bit of working to get back to the smooth texture it had been earlier
• Still quite translucent/ dilute pigment, mortar does not crush pigment as effectively as the muller appears to.
• Gather paint into small pool on glass by scraping together with the edge of a palette knife
• Used a clean (hogs hair) short bristle brush to paint onto the prepared gesso board (get details on board preparation) in section 3A.
• Very translucent when applied to the board
• Appears to be primarily clear oil with a few blue pigments suspended
• After drying the blue tint of the oil becomes more apparent but still quite a bit more translucent than it was on the board.
• Specks of pigment are evident in the not very consistently applied paint

Trial 2:

• Repeated the process using only one drop of walnut stand oil, about 3 palette tips full of verdigris and grinding with the muller instead
• Much easier grinding process
• The pigments appear to be uniformly incorporated into the oil quite soon after beginning to grind (about 15 seconds)
• Ground for about 1 minute (class was essentially over)
• Still quite translucent but a bit more opaque than last trial
• Gather pigment together with edge of palette knife
• Painted onto section 3B.
• Applies quite thinly, surprisingly translucent compared to the color on the ‘palette’
• After drying the strokes of the brush (though perhaps these are from the gesso layer beneath) become quite evident.
• Though applied smoothly, there are about as many suspended pigment fragments in this layer as in first trial.
• Dries to about the same color as original
• Will try again using twice as much pigment and perhaps half as much oil

---

Name: Njeri Ndungu
Date and Time:

2016.February.12, 4:45 pm

Location: Chandler 260
Subject: Verdigris Trial 3 (more extensive documentation)

Discussion with Cleo before trial:

• when adding oil to pigment some difficulty in controlling how much comes out because a drop from the syringe tends to be too large or to release two drops at a time: Cleo – usually uses brush to add incrementally; Njeri- used to allowing syringe to drip and knocking out single drop at a time - craft of artists vs craft of scientists

Trial:

• take copper plate out to begin scraping off pigment
• replace lid quickly because the acetic acid smell is very strong

• this time it was growing for four days in the fume hood
• still got wet somehow at the bottom (for some reason I often find my nose running when I work on these – maybe the vinegar irritation or some psychological response to pressure)
• the 20% is v volatile and want to condense on the sheet
• (get very chatty when working)

• the vinegar on the sheet when it touches the scrapped copper acetate immediately dissolves it. – to scrape need to ensure the palette knife is completely dry
• in the places that were damp then dried don’t scrape off with the same texture, not as easy
• scraped for about 5 minutes producing about
• short quick motions trying to get to the plate
• not able to harvest as much as desired because had only 15 minutes to work
• added new pigment to that harvested on Monday. They don’t seem that different, perhaps Monday’s was a bit darker?

• Drop from syringe on the side of the palette, still quite large
• Using walnut stand oil
• Dip tip of palette knife in it and mix with pigment incrementally

• Difficult to get a picture of the oil drop to record the amount used (see above)

• Thicker than last time not as much oil, more pigment used
• Wipe excess oil from side of palette so that it doesn’t get into pigment while mulling

• Clean muller from Cleo with walnut oil and mineral spirits
• Mulled for about 2 minutes but still quite grainy– obvious that one needs to grind for a long time to see change in texture

• Use palette knife to gather the paint in one spot.
• Will begin to grind again
• Decide not to grind again because too little time
• Took a paint brush from the tin can, tried to find the one that was the least stiff

• Application video:

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

---