Verdigris

Name: Charles Kang
Date and Time:

2016.09.16, 7:00 pm

Location: Upper East Side
Subject: Growing


Target Recipe: From manuscripts of Jehan le Begue, reprinted in Mary Philadelphia Merrifield, Original Treatises, Dating from the XIIth to XVIIIth Centuries on the Arts of Painting (London: John Murray, 1849), vol. 1, 124.

"155. How to make the green from brass which is called Greek or common green. - If you wish to make the copper-green which is called Greek, take a new jar, or any other concave vase, and put into it the strongest or most acid vinegar, so as not to fill it, and put strips of very clean copper or brass over the vinegar, so that they may not touch the vinegar or each other, being suspended to a stick placed across the vase. Then cover the vase and seal it, and put it into a warm place, or in dung, or under ground, and leave it so for six months, and then open the vase and scrape and shake out what you find in it, and on the strips of metal, into a clean vase, and put it in the sun to dry."

Materials and Ingredients

• A used glass jar with metal lid (cleaned and dried when distributed in class)
• A piece of sheet copper
• A length of twine (presumably cotton)
• Eden Organic Apple Cider Vinegar

Procedure

1. Instead of puncturing the copper, I folded a narrow strip (approx. 2 mm width) along one side so as to wrap over the twine.
2. I poured in slightly less than an inch of vinegar to the jar.
3. Holding the twine across the mouth of the jar - so that the copper would be suspended over the vinegar, I screwed on the lid.
4. The jar was then placed on a north-facing windowsill in my kitchen.

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Name: Charles Kang
Date and Time:

2016.10.03, 8:00 am

Location: Upper East Side
Subject: Separating Copper for Transportation

Procedure

1. I opened the jar for the first time since September 18. The sheet was covered with verdigris in an uneven fashion. I also noticed some dark green condensation on the surface.
2. I put the copper sheet in a small plastic zipper bag.

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Name: Charles Kang
Date and Time:

2016.10.03, ca. 11:30 am

Location: Making and Knowing Lab
Subject: Painting Out

PPE: safety glasses, rubber gloves, lab coat

Materials and Ingredients (in addition to the sheet copper and vinegar)

• Work surfaces: a small plastic bowl and a ceramic plate
• A small flexible painting knife (I later noticed that some art supply stores use "painting knife" to distinguish this type of knife from palette knifes (longer, broader, and not tapered - almost like a spatula); I think we referred to it as a palette knife in class)
• A small glass muller
• Two pipettes
• A flat oil brush (forgot to note the number)
• Linseed oil
• Walnut oil

Procedure I: Scraping

• After going over the safety info on verdigris (copper acetate) on Chemwatch with the glass, I proceeded to scraping the verdigris off the sheet copper into a small plastic bowl.

• Holding the knife by the blade allowed a better control of movement (quick and narrow) and pressure (strong enough to leave very feint marks on the sheet copper at times).

• Comparing the result with others, however, made me realize that I ended up with less verdigris (about a quarter teaspoon by eye) than most of my classmates. Possible factors to consider: late start date, vinegar quality, indirect sunlight and low ambient temperature during the growth.

• Once I scraped off as much verdigris as possible, I added two drops of the vinegar used for the growth. Perhaps because of the color of the vinegar (but also possibly because of the refractive quality of the liquid), the mixture looked darker than verdigris in its powder form.

• The bowl was placed in the fume hood to dry out.

Procedure II: Grinding & Mixing Oil

• Once dry, the verdigris-vinegar mixture was transferred to a ceramic plate (no glass plate available at the moment).

• I separated the verdigris-vinegar mixture into two small piles. Using a pipette, I added a few drops of walnut oil to one pile. I started grinding it with a glass muller.
• Compared to my previous experience of grinding pigment-oil mixtures - I must admit, that was back in high school (the late 1990s) - it was very difficult to determine whether this mixture was ground finely enough. There surface of the plate was uneven, and there was not enough mixture to drag around (in a figure 8 motion). I had to determine simply by eye whether the verdigris was sufficiently ground into the oil.
• I repeated steps 2 and 3 with the other pile of verdigris-vinegar mixture, adding a few drops of linseed oil. Probably because of the small quantity, I did not notice any difference in viscosity.

Procedure III: Painting Out

• Using a small flat oil brush, I filled in two prepared squares on a poster board using the two types of "paint" (i.e. pigment-oil mixture). It was then I noticed visible grains of verdigris. The paint was very thin (like a glaze), revealing some of the verdigris not fully ground into the oil.

• Other than the grains, I noticed very little difference in the resulting color.

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Name: Charles Kang
Date and Time:

2016.10.17, 2:26 pm

Location: Making and Knowing Lab
Subject: Observation

Two weeks have passed, and the swatches have discolored a bit. Both have darkened and looked greener - possibly due to the yellowing of the oil. The swatch with linseed oil, to confirm my familiarity with the material, has turned even darker and greener than the one with walnut oil.

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