FOR FIRST ATTEMPT AT THIS RECIPE, SEE OUR SAND CASTING FIELD NOTES

Historical Question:

Why does he refer to alabaster as a different substance for sand from plaster, when he explicitly states that alabaster and plaster are the same thing? What might the connotation of alabaster be? What might its perceived properties be, and how might those have an effect on the choice of material? Is there a substantial difference between making sand from powdered alabaster or powdered gypsum in terms of the final product?

NAME: Sofia Gans and Celia Durkin
DATE AND TIME: April 13, 2015, 11:00AM
LOCATION: 260 Chandler
SUBJECT:

Calcining powdered alabaster and gypsum

Materials:

• Powdered alabaster, sourced from Natural Pigments
• Powdered gypsum, sourced from Kelp4less

Process:

• filled two metal trays, one with powdered alabaster and one with powdered gypsum
  • the gypsum actually looked slightly whiter than the alabaster, but that could have been an illusion
• placed in the kiln at 49 degrees C, left to heat up to 170C, where it would stay for 1.5 hours

Building the "humid cave"

Materials:

• food dehydrator tray
• humidifier
• 3 terra-cotta plates
• milk cartons, yogurt containers, cans filled with water
• linen
• food dehydrator lid

Process:

• We had a humidifier and decided to build some sort of tower to place over the humidifier with the sand.
  • We chose terra-cotta plates to hold the sand, as it’s the kind of vessel that would have been used to store powders. Also it absorbs moisture well. We needed three plates, one for alabaster with 1 oz sal ammoniac, one for alabaster with 2oz sal ammoniac, and one for gypsum with 1 oz sal ammoniac.
    • we thought perhaps about using paper, as we knew it would be permeable, but I worried about the integrity of the paper, having it tear and have the sand spill everywhere by accident. Terra-cotta seemed safer.
  • We built a tower from yogurt containers and milk cartons weighted with water so they’d be stable. We used a food dehydrator tray to hold the terra-cotta plates. We directed the humidifier so it blew directly up through the center of the plates. We covered the plates with another plastic lid, then covered the whole thing in a large swath of linen to trap as much moisture as possible.
  • We hope that placing the dry sand in this environment for approximately 7 hours tomorrow will form a paste enough for molding.

NAME: Sofia Gans and Celia Durkin
DATE AND TIME: April 13, 2015, 3:45PM
LOCATION: 260 Chandler
SUBJECT:

Mixing in Sal Ammoniac and setting up "cave"

Materials:

• 10.5oz calcined alabaster
• 8oz calcined gypsum
• sal ammoniac

Process:

• powders came out of the kiln at 4PM. By 4:10PM they were cool and easy to handle.

• Alabaster

  • divided the 10.5oz of alabaster
  • mixed the first 5.25oz of alabaster with .3oz of sal ammoniac, staying approximately true to the ratio of 1 lb of alabaster to 1 oz of sal ammoniac. Placed the mixed salt and alabaster on the large round terra-cotta plate.
  • mixed the second 5.25oz of alabaster with .6oz of sal ammoniac, staying approximately true to the ratio of 1 lb of alabaster to 2 oz of sal ammoniac. Placed this batch on the small round terra-cotta plate.

• Gypsum

  • mixed 8oz of gypsum with .5oz sal ammoniac, staying true to the ratio of 1 lb of alabaster to 1 oz of sal ammoniac, as described in fol. 83r. Placed this batch on the large broken terra-cotta plate.
• Also decided at the last minute to include a dish of the already-mixed alabaster and sal ammoniac that we'd ground from raw stone a few weeks ago, having sieved it finely earlier today. We'll see if it actually works.

NAME: Sofia Gans and Celia Durkin
DATE AND TIME: April 14, 2015, 4:05PM
LOCATION: 260 Chandler
SUBJECT:

Packing the molds

Materials:

• humidified sand
• metal box molds
• small flat objects for casting

Process:

• Jef came in the morning and turned on the humidifier at 9AM, which had been fully set up the night before.
• By the time we arrived at 4PM, the sand had been humidified for 7 hours.the contraption worked impressively well. There was a significant accumulation of moisture on the linen cover, and opening it up revealed water pooled underneath, so clearly the system had succeeded in trapping moisture.
• the sand itself upon first touch seemed quite hard, but when probing it was easy to crumble, and could be returned to a fine consistency when pressed. It could be well-packed using the hand squeezing method.
  • in our previous attempt, when we added water by hand, it began to form hard lumps immediately that couldn’t be broken up with pressure, so clearly this slow process had produced a different result.
  • the commercial alabaster sand was distinctly more yellow than the gypsum or the initial raw alabaster.
• we packed the sand in box molds with various small objects to be cast
  • 1oz/lb commercial alabaster is in metal box mold with pegs sticking up, medal with woman’s face
  • 2oz/lb commercial alabaster is in metal box mold without pegs, shell
  • gypsum is in mason jar lid on terra-cotta shard, necklace pendant with bird
  • leftover raw alabaster is in mason jar lid on ceramic plate, random medallion with initials
• the molds were left to dry in the fume hood over night

NAME: Sofia Gans and Celia Durkin
DATE AND TIME: April 15, 2015, 9:00AM
LOCATION: 260 Chandler
SUBJECT:

Heating and Casting

Releasing the objects from the mold

• we first attempted to remove the portrait medal. It was stuck very firmly in the sand, which had become quite smooth and hard. I tried to dislodge it with a pestle, but it still didn’t work, so I used a needle tool to pry it loose. We didn’t use any separators, and a huge chunk of the sand came off with the medal, rendering it effectively useless. There was also evidence of some sort of chemical reaction, as the surface of the medal had begun to turn blue green.
• the next ones all removed fairly easily and seemed to leave a pretty clean impression. The bird necklace also seemed to have some sort of blue green tarnishing.

Heating in the kiln

• put the three molds in the kiln at 20 degrees around 9:10am. At 9:33am it was 80 degrees.

Casting into molds

• decided to cast using lead and tin alloy, referring to recipe on 72v
• we poured a little after 10am using a mixture of approx. 1.5 tin to 1 lead
  • paper test: 139r_c1_c
  • laid soapstone over the top of the mold after we poured to put pressure
• after letting them rest 20 minutes, we opened the molds
  • the shell had a flaw in the center that seemed to have stemmed from the way the metal was poured, but the detail of the rings of the shell, which wasn’t discernible in the mold itself, was readily apparent in the finished object
  • the bird necklace picked up a fair amount of detail in certain areas, but other areas were much less sharp. This seems to have been due to some crumbling that happened in the mold when the object was removed
  • the small Madrid medallion wasn’t poured correctly, so the metal pooled weirdly and very little detail was picked up.
  • we decided to attempt a second cast into all three molds to see what it would yield.
• at 10:42, put the molds back in the kiln at 79 degrees to reheat and cast again. Took them out at 11am, and cast the same mixture, covering the molds with soapstone once the metal was poured.
  • second casts were crumblier and less defined except for the Madrid medal, which was much more evenly cast than the first time.
    • I poured more material with more confidence on the second round, which seems to have made the metal fill the mold better.

Conclusions

• Despite really promising texture after humidifying, it seems that these sands don't pick up quite as cleanly as some of the other sands we've worked with. They crumbled slightly when the objects were removed from them, and the detail was generally lacking fineness in certain areas.
• All sands used seemed to work equally well despite differences in material, technique, and ratios. There didn't seem to be a quantifiable difference between alabaster, gypsum, or amounts of sal ammoniac.
  • it would have been nice to be able to cast the same object in each type of sand, as that could have allowed for more direct comparison.
• we were able to cast twice into the molds and pick up at least some detail on the second cast, which isn't always the case.
• we could/should perhaps try a separator next time to see if it results in finer detail and less crumbling on release.

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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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