RISD-M&K Ruby Making Collaborative Field Notes - 2016-11-01 to 2016-11-03

Participants

Field Notes

BASIC RECIPE & ORDER OF OPERATIONS:

• 3.54 g (1 dram) quartz pebbles, crushed to powder

• gathered at RISD farm beach; on Oct 25th heated to 1598*F for 1 hr; taken out for 10 min; put back in for 1 hr; taken out for 10 min; put back in for 1 hr; taken out and quenched in vinegar; broken into chunks in about 10 min with ease, then ground for about 2 hrs until quite a fine powder but not a soft fine powder

• 0.065 g (1 grain) gold (5 leaves of gold foil)

• From RISD store

• 10.62 g (3 drams) minium

• Also known as red lead, lead(IV) oxide, and lead tetroxide

• 0.8 g (or equivalent) additive (soda / potash / saltpeter)

• Soda (or soda ash) = sodium carbonate

• Industrial sodium carbonate
• RISD homemade ash = salt-marsh plants (gathered at RISD farm beach); calcined for 3 min in small quantities) [nb: this needs processing into soda ash, and it probably only contributed carbon to the melt [analyze the ash!]

• Potash = potassium carbonate
• Saltpeter = potassium nitrate

1. crush quartz in glass mortar and pestle until a fine powder (+/- 2 min)
2. fully incorporate gold leaves one at a time into powdered quartz
3. grind minium into the quartz-gold powder (+/- 5 min)
4. grind in additive (+/- 2 min)

Videos from Joel^[a]:

https://www.youtube.com/watch?v=EhFqXg1Awq8 

https://twitter.com/JAndrewKlein/status/793814555096911872 

See Flickr album:https://www.flickr.com/photos/128418753@N06/albums/72157672459260834

OVERVIEW OF SAMPLES:

See this spreadsheet

NOTE on NJR observations of results:

• Ad-hoc “technical” visual analysis was made of all samples, as well as investigations of sample textures, strength, and to pull out elements of interest for future analysis.
• Setup:

• A small-tipped metal screwdriver (in place of need needles, tweezers, scalpel, etc)
• Magnifying glass
• Flashlights and work-lamps for raked light

• All samples and sample elements were packed, labeled, and split between RISD and CU for future technical analysis

TUESDAY, NOV. 1, 2016

• 2 hr discussion about what trials we would undertake

• our overarching aim is to try the ms recipe for ruby (NB: a-p does not seem to have had success with this, as he mentions his failure, and observations that “some say” [cement gold many times, gold cemented with antimony; pebbles, gold, saltpeter produces color of peach]
• what seems to be constant (“the same dose for all gemstones”):

• 1 part crushed pebbles
• 3 parts minium
• 1 grain gold
• Is the sel de verre or sel achali constant for all gemstones?  It is only mentioned in the emerald recipe.
• All grinding is done in glass mortar and pestle

• what are the variables:

• Furnace: gas vs charcoal

• we thought we needed to do one in gas and one in charcoal, since the gas is an oxidizing (or NOT reducing) atmosphere while the charcoal is a reducing atmosphere, but then we realized that we could make the gas into a reducing atmosphere by choking it off with a brick at the top, so we decided to try homemade materials [only ash made from salt marsh grass] (for Batch 1 only)
• when you choke off the gas furnace, the reduction atmosphere starts at ca. 1000*F

• Additives:

• “sel achali” interpreted as sodium carbonate vs. as potassium carbonate vs. no salt at all (not mentioned in the ruby recipe)
• For soda ash, use of homemade RISD ashes or industrial sodium carbonate
• saltpeter or no saltpeter, and whether by itself or in addition to an alkali additive
• Amount of additive

• 0.8g was chosen based on Kremnitzer-Shah annotation on imitation gemstones (M&K, Fall 2015)
• Approved by Glen Cook

• From Reid Cooper’s presentation:

• Lead oxide acts as flux, redox couple, viscosity decreaser
• Higher alkali content in silicate melts, more oxidizing
• There is a solubility limit for ionic gold at certain temperatures

• Won’t necessarily ruin the melt but the gold just won’t incorporate if there is too much
• Could be reason for metal deposits in our samples?

• problem of the crucibles:

• we are using glazed porcelain crucibles and we used 1 aluminum-oxide crucible.  Both are problematic because the sodium, potassium, and aluminum leach into the glass melt (nb: molten glass is one of the most corrosive materials possible).  
• Better would be mullite or silmonite crucibles.  
• In the end, Glenn Cook thought that the glaze was not melting into the glass melt, and that we should keep the crucibles constant by using glazed porcelain.  We used on aluminum-oxide crucible in the pipe charcoal furnace on Nov. 1, 2016, but otherwise all glazed porcelain.

BATCH 1

Batch 1 Materials and Quantities:

• 3.54 (1 dram) crushed pebbles
• 0.065 g gold (1 grain (i.e., 5 leaves))
• 10.62 g (3 drams) minium (red lead; lead tetroxide)
• 0.8 g ash from salt-marsh plants (RISD homemade ash )
• Ground pebbles and gold for 10 minutes, and with the lead for 3-5 minutes, and with ash for 3-5 min. ~15-20 mins total

PHS's notes on grinding materials together in the glass mortar and pestle:

• we are striving for a soft, fine powder
• the quartz powder is pretty fine but still grates on the mortar
• quartz and 5 leaves of gold ground together for total of 10 minutes
• the gold leaves were added one at a time and each was incorporated fully before the next was added
• gold leaves incorporated surprisingly easily, and it worked best to pick the gold up with dry fingers
• lead was fatty and made grinding difficult because it caked up around the mortar’s sides and the pestle just slid over it.

Batch 1 Melt: Gas

• 1:15 pm - crucible in furnace but problems with the torch head—cannot light; crucible put back in the garage with batch 1 still inside.  Put into furnace when at 1117*F
• 1:25 - 1958*F
• 1:30 - 2160*F
• 1:40 - 2153*F
• 1:51 - 2187*F
• 2:01 - 2197*F
• 2:15 - 2194*F
• 2:30 - 2187*F
• 2:40 - 2173*F
• 2:55 - 2151*F
• 3:05 - 2170*F
• 3:30 - 2157*F
• 4:19 - 2136*F
• 4:28 - 2116*F and change map gas tank
• 4:35 - 2160*F
• 4:47 - 2131*F
• 4:55 - 2130*F
• 5:22 - 2202*F
• 5:40 - 2144*F
• 6:00 - 2188*F
• 6:20 - 2181*F
• 6:40 - 2173*F
• 6:50 - 2143*F

TOTAL: 5 hrs and 35 mins

Batch 1 Melt: Pipe

• Batch went into furnace at 5:10pm after crucible heated for 30 mins in garage, then charged and raced down the stairs
• crucible broke at edge just before 9pm, and it was removed.
• Hunter, Felicia, Camille working the pipe furnace for charge and removal
• Tall, cylindrical aluminum-oxide crucible

• Air circulation was poor for several reasons

• Coal pieces were too small and were clogging the furnace
• Bricks open on the bottom, so too much air on the bottom (and air not moving up due to coal clog)
• Oxygen torch was heating too much on the bottom (due to coal clog) while the top was too cold
• Blower was simply pushing air out and across the bottom out the vents because the two bricks supporting the furnace were parallel to one another

TOTAL melt time = ca 3 hours and 40 mins (crucible broke just before 9pm and was removed)

NJR observations of Batch 1 results

Batch 1 Pipe

• Lead beads crawling up the crucible sides

• Glen thinks this could be condensed vapourized lead

• Embedded piece of charcoal
• Overall green tinge under the ashes, with pockets of yellow
• Lots of small- and medium-sized lead beads across the bottom
• Under some of the ashy parts there are lime-green coloured areas
• On the bottom exterior of the crucible, there are lead beads scattered everywhere, almost pooling away from the big deposits of glass

• [AMDH Notes] Furnace Notes

Taken from an Interview with Camille - 11/03/16

11 melts in total

Day One - pipe and gas

Day Two - pipe and gas and brick x2

Day Three - pipe and gas and brick

Day One:

Outdoor Furnace - Hunter, Felicia, and Camille

• Pipe furnace only - in several iterations over the course of the day.
• Most of the day it was supported on parallel bricks. Grate, furnace can, top covered with two small bricks. Heated by oxygen torch and air circulated with a blower. Zirconium crucible. Crucible not super hot. - Charcoal was too small and the airflow got clogged.
• Oxygen torch heated crucible too much on the bottom - uneven heat distribution cracked the crucible.
• A stack was added later in the day, probably added while the crucible was in the oven but this should be confirmed with Hunter.

WEDNESDAY, NOV. 2, 2016

REVIEW of Batch 1 Results by group

• Examined results from Batch 1 firing from the night before
• Pipe charcoal furnace in aluminum-oxide crucible

• Glenn Cook says:

• beads of lead caused by charcoal reducing atmosphere--these are “reduced lead,” probably greater than 60% lead oxide
• yellowish-greenish color is created by the lead oxide

• Gas Furnace Batch #1

• many small lead beads; maybe a small gold bead; a small gold bit, and a small red bit [took to CU to analyze]
• deep green color at bottom of crucible, with lots of frothy grey matter at the top

• no stringers drawn so couldn’t compare to Charcoal furnace batch #1

• Glenn Cook says:

• color might be caused by contamination in the quartz; the marsh ash, the crucibles, the lead...
• there is no indication of gold-based coloring

Notes for Batch 2

• Since homemade ash was most probably not sodium carbonate, batch #2 will now try the recipe with industrial sodium carbonate (following the same recipe and steps as batch #1).
• Hunter and Camille have built a third furnace (the “box furnace”), so we are now able to test 3 samples per batch.
• From Glen:

• Sodium is a better flux than potassium
• (see “problem of crucibles” above) -- Question whether crucibles are acting as potassium/sodium fluxes. However, after examination of batch 1 samples, there seem to be no signs of this contamination because of our use of added fluxes (sodium/potassium carbonates) and the large volumes of our melts in relation to the size of crucibles

BATCH 2

Batch 2 Materials and Quantities:

• 3.54 (1 dram) crushed pebbles
• 0.065 g gold (1 grain (i.e., 5 leaves))
• 10.62 g minium (red lead; lead tetroxide)
• 0.8 g sodium carbonate (NA2CO3) (industrial-no number, just in plastic bag, labelled with sharpie from RISD)

• Mortar and pestle has not been cleaned out from the first mix, but we are following the same mix order as batch #1

• This means that there are traces of minium incorporated into the first grinding step, which makes the grinding process more difficult because of the lead’s “fattiness” (see PHS notes above)

• All three sub-batches (A, B, and C) use the same quantities but different grinding times:

• A: 15 min grinding time
• B: 8 min grinding time
• C: 8 min grinding time

Batch 2B Melt: Gas

• Rachel describing how she is going to take Batch 2B (which is in the rolled up paper cone) and transfer it to the crucible that Jocelyn is heating in the garage (1175*F).

• See DB Photo set 1

• 9:50 am - Jocelyn heats the crucible to the 1500s
• 9:54 am - Jocelyn turns off gas torch and opens furnace. She transfers in the filled crucible.
• 9:57 am - torch fired up and temp at 1512*F. Lowest temperature on the pyrometer during crucible loading was 909*F. Temperature is made to rise gradually over the next 10 minutes to 2100*F. Plan is to keep batch between 2100 and 2250*F.

• See DB Photo set 2

• 10:08 am - 2100*F
• 10:13 - 2163*F
• 10:30 - 2187*F
• 10:50 - 2193*F
• 11:10 - 2185*F
• 11:30 - 2168*F
• 11:50 - 2177*F
• 12:10 - 2205*F
• 12:30 - 2188*F and crucible removed from furnace

TOTAL: 2 HRS AND 40 MINS

Batch 2 Melt: Box Furnace - charcoal

• 11:32 am - Hunter heats the nest; Rachel preps the raw material
• 11:34 - material in crucible; crucible placed in nest with tweezers (tweezers not heated)
• 11:35 - nest on the move
• 11:36 - crucible transferred to furnace; hot coals placed over and around the crucible
• 3:58 pm - crucible removed from the furnace

TOTAL: 4 HRS AND 25 MINS

Batch 2 Melt: Pipe Furnace - charcoal

• 12:19 pm - Rachel puts the material into the cone
• 12:21 - Hunter heats the nest and tweezers
• 12:22 - raw material into crucible; crucible into nest
• 12:23 - crucible on the move
• 12:24 - transfer crucible into furnace; lid onto crucible; coal over and around crucible
• 12:25 - furnace reassembled and pipe exhaust put in place
• 5:00 pm - crucible removed from furnace

TOTAL: 4 HRS AND 45 MINS

• Crucible intentionally broken (Nov. 3) for ease of analysis

NJR observations of Batch 2 results

Batch 2B Gas

• Small lead beads at the bottom of the crucible
• Everything is much cleaner than the previous batches—it looks like glass!
• Piece with a small bead of lead at the top (c.f., other lead beads at bottom)
• Large lead deposit at bottom

• Pockets of yellow emanating from around the large lead deposit
• Half of it is covered by a matte circle

• When NJF dragged the screwdriver across it, an orange powder flaked off

Batch 2 Box

• charcoal got into melt
• Small beads of lead across the surface of the upper wall of the crucible
• Ashy part coming away easily, especially near the big lead bead which has an air ball right above it
• greenish yellow glass; which may have been lightened by annealing for striking

Batch 2 Pipe

• beautiful bright clear yellow that might have gold beads towards the bottom.  Stringers pulled easily when molten; it was very soft when annealed for striking, and turned a darker yellow
• After striking:

• There is an orange streak running through the yellow globule

BATCH 3

Notes for Batch 3

• Aim: Try potassium carbonate as additive instead of sodium carbonate
• Same amount of potash as soda is used (0.8g)
• HOWEVER, we later (after mixes have already been made) learn from Glen that by molecular weight, 0.8g of potash is double the molecular weight of 0.8g soda

• I.e. 0.8g potash = 1.6g soda in molecular weight
• So, for Batch 3, our alkali is doubled from Batches 1 & 2 in terms of molecular weight and the ratios of ingredients in the sample are different
• Ask Glen for his calculations

Batch 3 Materials and Quantities

• 3.54 (1 dram) crushed pebbles

• gathered at RISD farm beach; on Oct 25th heated to 1598*F for 1 hr; taken out for 10 min; put back in for 1 hr; taken out for 10 min; put back in for 1 hr; taken out and quenched in vinegar; broken into chunks in about 10 min with ease, then ground for about 2 hrs until quite a fine powder but not a soft fine powder

• 0.065 g gold (1 grain (i.e., 5 leaves))
• 10.62 g minium (red lead; lead tetroxide)
• 0.8 g potash (potassium carbonate)

• Fisher Chemical P208-500, LOT 144812

Batch 3 Melt: Gas [3B]

Ground for ca 6 minutes total

• 7:20 pm - 1590*F (lowest temp)
• 7:27 - 2136*F and brick placed on furnace lid to choke
• 7:32 - 2200*F
• 7:44 - 2161*F
• 7:55 - 2185*F
• 8:06 - 2163*F
• 8:25 - 2178*F
• 8:46 - 2161*F
• 9:01 - 2223*F and furnace adjusted
• 9:18 - 2179*F
• 9:30 - 2163*F
• 9:52 - 2197*F
• 10:41 pm - crucible removed from furnace

TOTAL: 3 HRS AND 20 MINS

• Crucible intentionally broken (Nov. 3) for ease of analysis

Batch 3 Melt: Box [3A]

Ground for 7 minutes total

• 6:30pm start heating
• 10:30 removed from furnace

TOTAL: 4 HRS

• temp measured by thermocouple at 10:15pm--hight point was 1747*F, but fluctuating temp, and the crucible is probably in the coolest part of the furnace

• Crucible intentionally broken (Nov. 3) for ease of analysis

Batch 3 Melt: Pipe [3C]

Ground for 7 minutes total

• 6:40pm start in furnace
• 10:40pm removed from furnace

TOTAL: 4 HRS

• heat measured at 10:30 by thermocouple--high point at the top of the furnace was 1260*F and at the bottom of the furnace was 2127*F (heat was not fluctuating as much as in the box furnace)

• Crucible intentionally broken (Nov. 3) for ease of analysis

NJR observations of Batch 3 results

Batch 3 Box

• Pulled a couple lead balls from halfway up the crucible wall (fairly easily)
• The lead in this sample generally is more malleable and come away much more easily from the crucible
• Big lead deposit in the center at the bottom

• Seemed to have a thin layer of glass across half of it (SECTION A in figure above) - it was shiny and vitreous

• Pulled off and kept for analysis

• The lead underneath this layer is much lighter than the exposed half (SECTION B). Section B is also sunken down
• Section B still seems to have some material on top of it
• Section A is pretty malleable and soft when NJR pokes at it with the fine screwdriver. It does not take much effort to scrape parts off. The color of the material revealed by scraping is the same as the scrapings

Batch 3C Pipe

• The lid was cracked open but stuck to the crucible; we broke off the lid and shattered the crucible to see inside
• The whole surface is covered in ash
• Lots of beads of metal
• Tide line of small lead beads above the glass
• We wiped out the inside of the crucible with a dry paper towel; now we see:

• Darker green colour around the edges where it is also thicker
• Where the pulls were made from the sample, it is a lighter green

• We wiped out the inside with a wet paper towel; now we see:

• White specks interspersed with the lead balls—??crucible chunks??
• The largest lead ball (which is medium-sized compared to the lead balls in the other results) is nestled in the light green part under the biggest pull

• AMDH notes: from the shape of the pull, it seems like the glass had an uncommon texture—stickier and denser than the honey consistency of soft glass
• In the top part of the crucible there is a tide line of lead beads but there are more lead beads scattered above the line, some of them surrounded by a yellow-green almost orange colour
• On the outside of the crucible there is purple—???

• Possible glaze reaction or effect from the charcoal surrounds in furnace

STRIKING

• Around 10 am this morning, Dedo gives Donna an update about conversation with about striking. During this conversation, the temp of the batch is, in fact, being kept in the high 2100s. This is to be able to compare it to the outcome of yesterday's gas oven experiment, in which the only difference in the batch and its temperature is the substitution of industrial sodium carbonate for the homemade saltmarsh plant soda.

• See DB video.

• Dedo's thoughts on today's plans to strike yesterday's material:

• One of two things will happen: 1) nothing; 2) we will get an ugly brown. The latter would be "a tremendous triumph" because it would show we are on the right path. Dedo goes on to describe the process: There is a very tight window between 10 and 40 nanometers in which the ruby glass can be produced. Nanoparticles above 40 nanometers in diameter are too big to produce a ruby colour, resulting in an ugly brown instead.

• See DB Photo set 3

• Evan used a torch to strike the samples. The mix was approximately 15 psi of oxygen and 6 psi of propane
• One sample struck from Gas 1, Pipe 1, Gas 2, Pipe 2, Box 2
• Evan’s process:

• Heat each single sample gently

• There was no change, so…

• Heat each sample more aggressively

• When they beaded up, it looked like metal burned off and we ended up with cleaner and clearer glass
• There was sometimes a colour change from an original scummy green toward a variety of clearer yellows

• Since the aggressive heating might have altered the glass at a chemical level, Evan left each to cool and returned with heat, thinking this might be the actual “strike” we were looking for

• In all cases, there was no change after second strike

[AMDH Notes]

Furnace Notes

Taken from an Interview with Camille - 11/03/16

Day Two:

Outdoor Furnace - Camille, Felicia, Hunter, Anya, Raghvi, Yiyi, Mike (night shift)

• Chimney on brick not put on until the evening around 7 to improve the temp.
• Pipe stove better ventilated - angled bricks on bottom makes heat more efficient.
• Hunter and Felicia decided to build the 2nd furnace.
• Pipe stove fed every 2-4 minutes depending on the discretion of the worker.

THURSDAY, NOV. 3, 2016

• Discussion in morning between Pamela, Glen, Dedo, Naomi, Rachel, and Jocelyne about trials for today
• While the previous three batches have had the same mixes in all two or three furnaces, the decision was made to do different mixes in every furnace today

BATCH 4

Notes for Batch 3

• From Glen

• Commercial lead silicates are usually potassium lead silicates (rather than sodium) because they are more stable and have better incorporations
• Saltpeter is more oxidizing

• Molar weight of saltpeter is double that of potash and quadruple that of soda.

• Decision was made to keep the “additive” ingredient at the same total molecular weight as Batch 3’s potash (which was double that of soda’s)
• When additive was just saltpeter, 0.4g was added (=0.8g potash or 1.6g soda in molecular weight)
• When additive was potash + saltpeter, 0.2g saltpeter and 0.4g potash were added (0.6g material total) (=0.8g potash or 1.6g soda in molecular weight)

• Furnace change

• Make the gas furnace as oxidizing an environment as possible (rather than a reducing one as we have been doing previously) AND  lower the temp by 100C

Batch 4 Materials and Quantities

• 3.54 (1 dram) crushed pebbles

• gathered at RISD farm beach; on Oct 25th heated to 1598*F for 1 hr; taken out for 10 min; put back in for 1 hr; taken out for 10 min; put back in for 1 hr; taken out and quenched in vinegar; broken into chunks in about 10 min with ease, then ground for about 2 hrs until quite a fine powder but not a soft fine powder

• 0.065 g gold (1 grain (i.e., 5 leaves))
• 10.62 g minium (red lead; lead tetroxide)
• additive

• 4A = NO ADDITIVE
• 4B = 0.4 g saltpeter (potassium nitrate) AND short firing time (2 hrs)

• Saltpeter: Chem Scientific P170, Lot 161012-4C

• 4C = 0.4 g potash (potassium carbonate) AND 0.2 g saltpeter (potassium nitrate)

• Potash: Fisher Chemical P208-500, Lot 144812
• Saltpeter: Chem Scientific P170, Lot 161012-4C

• 4D = 0.4 g saltpeter (potassium nitrate) AND long firing time (VERIFY EXACT TIMING AFTER FIRING= 4 hrs and 30 mins)

• Saltpeter: Chem Scientific P170, Lot 161012-4C

Batch 4B Melt: Gas (short firing time)

Grinding time: total of 10 mins

Jocelyne, Rachel

• 9:48 am - Crucible from garage to loading brick; Material into crucible; Crucible into furnace
• 9:49 - Lid on crucible in furnace; Gas torch lit; Lowest temperature on pyrometer: 1125*F; Cover placed on furnace
• 9:52 - 2074*F and brick placed on top of furnace opening to choke
• 10:00 - 2172*F
• 10:15 - 2144*F
• 10:20 - decision to bring furnace down to temp of 2012*F
• 10:30 - 2013*F
• 10:45 - 2022*F
• 11:00 - 2025*F
• 11:15 - 2012*F
• 11:30 - 2023*F
• 11:40 - 2022*F and crucible removed
• Crucible intentionally broken (Nov. 3) for ease of analysis

Batch 4A Melt: Box

Grinding time: total of 10 minutes

Jocelyne, Rachel, Hunter, Camille

• 10:16 am - nest heated with torch; crucible from garage to loading brick; material in crucible
• 10:17 - crucible in nest; lid on crucible; Jocelyne takes crucible down the stairs covering it with thermal mittens
• 10:18 - crucible in nest arrives at box furnace; torching crucible from the top to keep it warm; Hunter, Camille, et al open furnace and arrange coals
• 10:19 - crucible in furnace; coals placed around and on top
• 10:20 - cover on furnace; triangular bricks arranged on top
• 5:00 pm - crucible removed from furnacE

TOTAL: 6 HRS AND 40 MINS

• At some point during firing, crucible tipped over; lid fused to crucible body; some material escaped and fired on exterior
• Crucible intentionally broken (Nov. 3) for ease of analysis

Batch 4C Melt: Pipe

grinding time: total of 10 mins.

Jocelyne, Rachel, Hunter, Camille

• 10:23 am - nest heated with torch; crucible from garage to loading brick; material in crucible; crucible in nest
• 10:24 - lid on crucible; Jocelyne takes crucible down the stairs covering it with thermal mittens
• 10:25 - furnace opened; crucible in nest arrives at pipe furnace; Hunter, Camille, et al shuffle coals in furnace
• 10:26 - crucible in furnace; coals piled around and on top
• 10:27 - cover placed on furnace; pipe positioned atop cover; triangular bricks arranged around bottom of pipe
• 5:05 pm - crucible removed from furnace

TOTAL: 6 HRS AND 30 MINS

• At some point during firing, crucible tipped over; lid fused to crucible body; some material escaped and fired on exterior
• Crucible intentionally broken (Nov. 3) for ease of analysis

Batch 4D Melt: Gas (long firing time)

grinding time: ??? [ground by Dedo with Thijs and Tianna? in attendance]

• 12:28 pm - crucible in and temperature at 1491*F; no brick to choke
• 12:32 - 1945*F
• 12:40 - 2014*F
• 12:55 - 1980*F
• 1:10 - 2006*F
• 1:25 - 2022*F
• 1:40 - 2001*F
• 2:00 - 1998*F
• 2:15 - 2018*F
• 2:30 - 2015*F
• 2:45 - 2010*F
• 3:00 - 2008*F
• 3:15 - 2006*F
• 3:30 - 2013*F
• 3:45 - 2012*F
• 4:00 - 2011*F
• 4:15 - 2011*F and new cannister dropped low, oscillated between very low and very high for a minute
• 4:33 - 1985*F
• 4:45 - 2038*F
• 5:00 - crucible removed from the furnace

4 HRS AND 30 MINS

• Crucible intentionally broken (Nov. 3) for ease of analysis

NJR observations of Batch 4 results

Batch 4B Gas

• Ashy deposit on the top of the sample is much harder than it was on any of the previous results and there appears to be less of it overall
• The side that has more ash buildup looks darker in the glass section than it does in the previous results
• On the lid of the crucible, there are patches of lighter and darker green, there are patches of yellow-orange, and there are lead beads of various sizes
• Crucible intentionally broken (Nov. 3) for ease of analysis

• Lead ball came out upon smashing crucible

Batch 4A Box

• Glen says it was a very fluid melt
• Some of the escaped melt fused the lid to the crucible and could still be found between the two

Batch 4C Pipe

• Gold balls

STRIKING

• Evan in charge of striking again, with same gas mixture in torch as before
• Two samples struck for Box 3, Gas 3, Pipe 3, and Gas 4

• One struck with gentler heat
• One struck more aggressively

• struck a second time after an initial cooling

• General observation: potash glass is much less reactive than the soda glass

• It is becoming clearer upon striking

Box 3

• Very little alkali flare
• Stick piece heated gently
• Chunk heated aggressively and melted down into bead

• Cooled & struck a second time: no change

Gas 3

• Curved stick sample heated gently

• Metal can be seen on surface

• Long, thin stick sample heated aggressively

• Stick disintegrated into small, clearer beads

Pipe 3

• First piece heated gently
• Second piece torched aggressively to drip off into a bead

• Cooled & struck a second time: no change

Gas 4b

• Smaller chunk heated gently

• Something on the surface is boiling off
• Greenish clear gold

• Bigger chunk (tadpole shaped) heated aggressively

• Metal on surface melting and gathering
• Tail of glass shrunk in on itself, pulling into the larger mass
• Glass glowing and glittering under the flame
• Entire piece now becomes a uniform, molten globule
• Black ring of lead oxide formed around the glass on the stone
• Cooled & struck a second time: no change
• Glass stuck to stone—shattered when later pried off

[AMDH Notes]

Furnace Notes

Taken from an Interview with Camille - 11/03/16

Day Three:

Outdoor Furnace - Camille, Felicia, Hunter Jorge, Yiyi, Evan, Mike

• Chimney put on brick furnace
• Fire is fed when the level of charcoal is lower and the flame is not visible.

Other investigations - Glen Cook and Naomi

• Impurities in lead

• See lead pigments folder for reference material
• Is it possible that the lead used historically contained impurities that helped with the redox exchange essential to the ruby red color (eg zinc, tin)?
•  Lead tetroxide is produced by heating lead carbonate → lead(II) oxide (yellow lead), then heated → lead(IV) oxide
• Lead carbonate is produced from elemental lead, so any impurities in the lead used to make lead carbonate could be present in lead tetroxide
• Look into historical metallurgical mining
• From Pamela:

• Look at Galena (natural mineral form of lead(II) sulfide), silver mining, lead as by-product, separation process

• 15th c - new process, Germans

• Look at Biringuccio, Agricola (use Hoover edition) on lead
• Possible avenues for further investigation: production of armor, stained glass windows
• People to contact: Arie Wallert, Erma Hermens, Maryan Ainsworth, Maartje Stols-Witlox (white lead)
• Readings to look at:

• Faries (2001) - “Early Netherlandish Painting at the Crossroads…”
• Bucklow - white lead in “Matter of Art”
• 1972 Rado…
• Kingry Bowen + Owen

NOTE: [AMDH] - p. 447 of De Re Metallica describes the formation of a button of silver in a melt of glass that sounds like what we saw at RISD. - What we were doing may have been a way to separate out metals?