Calcined Alabaster as Excellent Sand
by Sofia Gans
<title id=”p083r_a6”>Sable excellent</title>
<ab id=”p083r_b6”>Albastre calcine dans un crusol a foeu de charbon tant quen le<lb/>
touchant il vienne en pouldre Esta{n}t froit pulverises le subtilem{ent}<lb/>
& passes par un double tamis & le rendes co{mm}e impalpable Et d avecq<lb/>
une lb de albastre il fault une ℥ de sel armoniac Mesles bien<lb/>
& incorpores tout ensemble Puys le mettes dans une cave cave ou<lb/>
lieu humide et de ceste paste moulles ce quil vous fauldra & apres<lb/>
seiches le moule au foeu & y gectes tel metal quil vous plaira<lb/>
pendant que le sable est chault & vous gecteres aussy net que le principal<lb/>
& le sable sert tousjours le mectant en lieu humide & seichant au foeu</ab>
<title id=”p083r_a6”>Excellent sand</title>
<ab id=”p083r_b6”>Burn alabaster in a crusol under charcoal fire until [upon touching it] it turns into powder. Once [it is] cold, finely pulverise it [and pass it] through a sieve to make it impalpable. With a pound of alabaster, one should use an ounce of sal ammoniac. Mix well and incorporate everything together. Next, put it in a cellar or a wet location. And with this paste, mold whatever you need and then dry the mold under a fire. While the sand is hot, you cast whatever metal you may like and your cast will be as neat as the principal. And the sand [will] always work if it is kept in a wet location and dried by the fire.</ab>
The recipe for “Excellent Sand” on fol. 83r falls among a list of various sands and techniques for use in box molds. Most “sands” in the manuscript call for some sort of dry powder, which is then combined with a liquid binder. This recipe follows such a pattern, calling for the powder of burned alabaster, ground and well-sieved, mixed with a certain ratio of sal ammoniac, and left to humidify until it forms a paste. Two different types of stones are known as alabaster. One, calcite alabaster, is found primarily in the Middle and Near East. The other, which would have likely been that used by the author, is called gypsum alabaster, and is found throughout continental Europe and the United Kingdom. Gypsum alabaster is a fine white stone understood today to be of the same chemical composition as gypsum, CaSO4·2H2O. When heated, both substances release their water molecules and become calcium sulfate hemihydrate, which is plaster.1 The use of plaster (also denoted as a “sand”) is widespread in the manuscript, notably as a mold material used in life casting. While the plaster in these recipes would have been a liquid poured around the object (plant, animal, flower, etc.) that was to be cast in a clay mold, the sand referred to here would be for box molding, wherein the object to be reproduced is pressed into damp sand held in a wooden frame. The manuscript’s author-practitioner was clearly aware of the material connection between plaster and alabaster, as he notes in the margin of fol. 125v that “Lalbastre co{mmun}ement apelle qui touteffois est plastre est bien dur mays il se retire fort” (Alabaster, which is plaster in any case, is very hard, but it shrinks quite a bit).2 Thus, we set out to determine whether there was a qualitative difference between sand made with pulverized alabaster and that made with plaster that would cause the author-practitioner to mention alabaster by name as a specifically “excellent” material for molding sand. And if there is no clear difference between the products cast in alabaster and in plaster, what might account for his inclusion of each as a distinct mold material? We investigate here not only the physical properties of alabaster sand, but also its symbolic connotations, as they reveal much about its status as an elite material in late medieval and early modern Europe, which might have encouraged our author-practitioner to highlight its excellence.
This recipe falls among a variety of others addressing the composition of various sands. The search for the perfect mold sand seems to have preoccupied not only our author-practitioner, but many early modern craftsmen whose technical writings have come down to us.3 Additionally, the process followed in this recipe is comparable to several other sand recipes, most notably that for sand using powdered ox bone and rock salt on fol. 89r. Both use a calcined raw material that is then finely ground, mixed with salt, and humidified to form a paste for molding. The annotation for ox bone lays out how salt acts as a binder in this class of recipes, rather than the various forms of liquid binders mentioned.4 It is clear that for the early modern craftsman, mold materials were of equal intellectual and experimental interest as the metals themselves. Of course, these molds rarely survived past the production process, and thus our text-based reconstructions are some of the only ways to shed light on the properties of these various mold materials. It remained for us to determine the properties of alabaster.
Our author was not the only one to deal with burned alabaster as a mold material. Hugh Plat, in The Jewel House of Art and Nature, first printed in London in 1594, describes in the section “The Art of Molding and Casting” how to prepare molds for casting branches or flowers from life from a mixture of “burnt alabaster and plaister of Paris” in equal portions.5 As in our manuscript, he recommends to mix three parts of this alabaster and plaster mixture to one part ground brick or terra cotta tile, a small amount of “spawd,”6 and water with sal ammoniac. He also mentions that if one wants to cast in wax, the mold can be made from plaster or alabaster alone, or a mixture of the two. Of course, this is a liquid mold material for life casting, rather than a “sand”-filled box mold. However, it is interesting to note that our author is not the only one to see a distinction between the chemically identical materials of burnt alabaster and plaster of Paris. Indeed, contemporary pigment companies such as the German Kremer Pigments sell “Alabaster Modellgips” (modeling plaster), which they claim is “von primärer Kristallinität und erhärtet besonders hart und durchscheinend”7 (of prime crystallinity and hardens particularly hard and translucent). This provides further impetus for our comparative experiment.
We began our experiments with 2 kg of raw gypsum alabaster. After laboriously breaking the raw stones into smaller chunks to facilitate even calcination, we calcined them in both a toaster oven in the lab and in our home ovens. A bit of research determined that alabaster calcines at approximately 170 degrees Celsius.8 The manuscript indicates to calcine the stones “tant quen le touchant il vienne en pouldre” (until they powder at the touch).9 Initially we assumed this meant that the stones would disintegrate with pressure when they were fully heated, but we eventually realized that it probably referred to more of a visually powdery surface that would form on the stone fragments, which then still needed to be ground in a mortar once cool. By an hour and a half in the oven, the stone fragments had turned a pure white, and the small pieces could be crushed with relatively little force [Figure 1, video of crushing calcined alabaster chunks]. We determined that this indicated the completion of the calcination process. The next step was to “pulverises le subtilem{ent}”10 (gently grind the stones) and sieve them through a “double tamis”11 (double sieve). We ground the stones in marble mortar and pestles, and sieved them through tightly woven cheesecloth lining a plastic sieve. Despite calcination, this was a labor-intensive process that required many rounds of sieving to achieve the desired “impalpable” consistency. Even at the end of our labors the powder wasn’t quite impalpable; small granules could be detected when the powder was rubbed between fingertips.12
In this instance, the ratio of sal ammoniac required is mentioned directly in the recipe: “avecq une lb de albastre il fault une ℥ de sel armoniac” (with a pound of alabaster, one should use an ounce of sal ammoniac). However, a recipe a few pages later, on fol. 89v, also deals with sal ammoniac and calcined alabaster as materials for sand which “moule fort net & est de tres belle despouille”13 (molds very cleanly and is easily removed from the mold). In this instance, the author-practitioner recommends two ounces of sal ammoniac for a pound of alabaster. We decided to divide our calcined alabaster and make one mold using one ounce of sal ammoniac, and the other with two. We mixed the sal ammoniac (i.e. modern ammonium chloride, which comes in the form of small granular crystals like table salt) with the alabaster powder.
The next step was to simulate the “cave ou lieu humide”14 (cellar or damp location) in which the powder was meant to rest until it formed a “paste.” As we did not have a humidifier on hand, our initial attempt involved soaking fabric in water and leaving these rags in a cabinet with our sand overnight [Figure 2, initial attempt at humidifying the sand]. This produced no discernable change in the powder mixture, and we resorted to mixing water in slowly by hand until a paste-like consistency was reached that, when squeezed, would stick together firmly without being too wet. We had to add the water very slowly and mix vigorously with our fingers, as if we poured too quickly, the mixture would form large hard clumps that had to be reground.15 An apparently appropriate consistency was reached after the addition of 20 ml of water [Figure 3, the “squeeze” test showing how the sand material stuck together].16 We were then ready to pack our wooden box molds. We applied vine charcoal as a separator on the surface of our plaster medals [Figure 4, the plaster medallion to be cast with charcoal separato applied],17 before carefully packing the damp sand around them to fill the molds [Figure 5, packing our box mold].
The recipe indicates that the molds must be “chault” (hot or warm) to be cast into, so our next step was to heat them. We chose to do so in a toaster oven at 400 degrees Fahrenheit. Unfortunately, at this point our wooden box molds caught fire and we had to start the project from scratch.18 To avoid having to repeat the laborious process of regrinding alabaster, we decided to purchase pure powdered alabaster ground from raw stones mined in Volterra, Italy. We additionally bought pure powdered gypsum mined in Utah in order to determine if there was a difference between alabaster and gypsum once both were reduced to powder. These substances were calcined at 170 degrees Celsius in the kiln for an hour and half [Figure 6, commercial alabaster and gypsum powders in the kiln], and the two different ratios of sal ammoniac were mixed in.
To humidify this batch, we acquired a humidifier and decided to set up a system that would expose the powder to moisture in a more sustained way. The different calcined powders were put on terracotta plates and elevated so that the humidifier could blow directly beneath them [Figure 7, the elevated terra-cotta plates]. These powders were then covered with a domed plastic lid, and the whole apparatus was draped in linen to trap moisture [Figure 8, the humidifying set-up]. The sand was left to humidify for seven hours. The resulting sand was quite satisfactory for packing, fairly hard to the touch but easy to break apart with light pressure, and held its form readily when pressed, as described on fol. 118v “Casting in a box mold” [Figure 9, the “squeeze” test]. It was interesting to note that the gypsum powder remained fairly white, while the alabaster powder looked slightly more yellow in its paste form. We packed four molds, one with calcined commercial alabaster powder and one ounce of sal ammoniac, one with calcined commercial alabaster powder and two ounces of sal ammoniac, one with the leftover calcined alabaster powder ground from the raw stone mixed with one ounce of sal ammoniac, and one with calcined commercial gypsum powder and one ounce of sal ammoniac. These molds were left to dry overnight in the fume hood [Figure 10, packing the box molds].
The next day, we removed the models from each mold.19 Most came away relatively cleanly [Figures 11, 12, 13, impressions in the box molds], however the portrait medal we used in the commercial alabaster with one ounce of sal ammoniac did not [Figure 14, failed portrait medal mold]. A huge chunk of the mold material stuck to the surface of the medal, and a chemical reaction occurred leaving a blue residue on the medal’s surface, rendering this mold unusable. The remaining three molds were placed in the kiln to warm for 30 minutes at 80 degrees Celsius [Figure 15, box molds in the kiln to warm for casting]. We cast a tin/lead alloy in a ratio of approximately 1.5 parts tin to 1 part lead, as described on fol. 139r, testing when the metal was hot enough to pour using a piece of paper [Figure 16, the paper used to test the heat of the metal], as described in a marginal note on fol. 72v. When the paper turned brown, we poured the metal into the open top of each mold [Figure 17, pouring the tin/lead mixture]. In order to maintain pressure and allow the metal to cool and flow evenly, as soon as it was poured, we placed flat pieces of soapstone over the open mold until the metal had cooled [Figure 18, the molds with soapstone covers].
The results were not surprising: there was no discernable difference between the impressions of objects cast in alabaster versus those cast in gypsum [Figure 19, 20, 21, the results of our casts with the original models for comparison]. As to the “excellence” of our sand, the finished objects did not come out as cleanly as we would have expected from our subjective understanding of what “excellent” sand for molding could accomplish. This is likely due to our inexperience with box molding more than any fault with the material.20 While a certain amount of detail was picked up in each, the most subtle surface gradations were not captured. This was especially evident on the cast of a necklace pendant with a relief of a bird perched on a branch [Figure 21, cast of bird pendant]. The original had quite fine outlines of individual feathers on the wings and tail, which were barely registered in the cast replica. However, the very fine feet of the bird, as well as the branch on which it was perched, were picked up clearly. The flat surface surrounding the bird showed evidence of granularity. The edges of each object weren’t very cleanly impressed, as the edges of the impressions crumbled slightly when the objects were initially removed from the molds. Despite these imperfections, it was clear that this was a sand that packed quite well and dried quite hard, but again, no differently whether it was made of gypsum or alabaster. So, if alabaster is no different from plaster when calcined in terms of the impression it picks up, why was it specifically indicated as an excellent sand for casting?
Alabaster is of course best known as a fine material for carving sculpture, prized for its pure white color, its surface capable of being highly polished, and its softness allowing for ease of carving. Both it and gypsum are extracted from the same quarries, though alabaster is much rarer. Most of the material quarried in alabaster quarries is gypsum, which is too soft and crumbly to be carved, and was sold as raw material for plaster.21 Acclaimed alabaster sculptures were produced in several artistic centers in Europe during the Middle Ages and early modern era. Most well-known are probably the English workshops centered in South Derbyshire and Staffordshire which, beginning in the mid-14th century, produced thousands of relatively small-scale alabaster devotional images.22 The popularity and affordability of these prolific workshops resulted in the purchase and transport of their products across Europe, until Henry VIII put a stop to production during his campaign against the Church and its devotional furnishings.
More relevant for our author-practitioner are likely the Burgundian ducal workshops that produced breathtakingly intricate alabaster tombs for several generations of dukes in their administrative capital of Dijon. These tombs [Figure 22-23, tomb of Duke Philip the Bold and Duke John the Fearless of Burgundy, Musée des beaux-arts, Dijon] consist of fully-painted white marble effigies reclining on black marble slabs, which are in turn supported by elaborate micro-architectural arcades of alabaster, populated with small alabaster mourning figures [Figure 24, an alabaster mourning figure from the tomb of Duke John the Fearless, Musée des beaux-arts, Dijon]. It is these mourners that have received most attention, due to their arresting detail and life-like gestures. Unlike the marble effigies, these sculptures were only sparingly painted, highlighting the glowing white surface of the alabaster. The choice to leave the alabaster surface exposed indicates a certain reverence for the stone itself.23 Indeed, the contracts for each tomb explicitly specify alabaster as the material to be used for the tomb,24 and there were several documented delays in production due to difficulty securing enough alabaster.25 The clear importance of alabaster specifically as a material for such an elite project is evidence that it held a high position in the hierarchy of stone for sculpting in the region of Burgundy. Additionally, there are surviving alabaster sculptures from the Toulouse region [Figure 25, an alabaster sculpture of St. Margaret of Antioch carved in Toulouse in the late 15th century, The Metropolitan Museum of Art] that also seem to have been left unpainted, and would have circulated among an elite audience. One can imagine the metalworker visiting the workshops of these sculptors and reclaiming the dust leftover from carving to use as molding sand. In fact, we might consider that, knowing of alabaster sculpture’s hard shining surface, and that fact that these objects displayed particularly crisp details (due to the stone’s ease of carving), our author-practitioner might have hazarded that it would be a hard, durable mold material especially suited to capturing the minute details and contours of the object to be reproduced.26
The use of alabaster for tomb sculptures was not only tied to its fine appearance, but also to its theological significance. Alabaster is referred to in the gospels, in Mark 14:3, Matthew 26:6-7, and Luke 7:36-38. Though the location of the story differs according to each author, the basic story is the same: a pious woman comes to Christ bearing an alabaster jar full of precious ointment, which she uses to anoint him. Mark additionally specifies that the woman breaks the jar of alabaster to access the ointment. This moment received sustained exegetical attention from early Christian theologians such as St. Augustine27 and St. Jerome.28 Aleksandra Lipinska sums up the interpretation of this moment as such: “The woman bringing the jar signifies the Church; the alabastron [alabaster jar] filled with perfume oil symbolizes the body of Christ filled up with faith; and the breaking of the vessel stands for the death of Christ on the Cross…”29 This trope was extended to encompass the bodies of the faithful as well. Twelfth-century english abbot Aelred of Rievaulx writes to his followers to “Break then the alabaster of your heart and whatever devotion you have, […], pour it all out upon your Bridegroom’s head, while you adore the man in God and God in the man.”30 The association of alabaster with the body of Christ, and by extension the bodies of the faithful who modeled themselves in the image of Christ, led to its use in funerary sculpture as a symbol of the body’s potential for resurrection. This coupled with its remarkable similarities in tone and texture to human flesh when highly finished made it a potent, polyvalent material.
Marble was another such material celebrated for its ability to mimic flesh. In this vein, there is evidence that in Europe in the late Middle Ages, alabaster was sometimes called marble, and vice versa. For instance, the arcades of the tomb of Duke Philip the Bold were referred to in medieval sources as alabaster, however recent analysis has shown that they are actually white marble.31 Aleksandra Lipinska argues that this indicates that up until the 18th century “alabaster, like other polishable minerals and rocks, was counted among the family of marbles.”32 Marble, with its ancient imperial connotations, was a stone of great power and prestige, and alabaster took on those associations.33 Pliny the Elder was perhaps the first to associate marble and alabaster, referring in Book X of his Natural History to a stone called onyx marble that is sometimes called alabastrites. Though he is likely referring to calcite alabaster, as mentions the stone is found in Egypt, he specifically states that this type of stone “is suitable too, when burnt, for plasters.”34 Thus we see as early as the first century AD, the continuum between marble, alabaster and plaster was codified. Medieval lapidaries continued to group alabaster as a type of marble, for instance Isidore of Seville in his Etymologies. There, alabaster is included among a list of other marbles, described as “a white stone, tinted here and there with various colors.”35 However, he, too is referring to calcite alabaster, as he states that the whitest stones are to be found in Egypt, Syria, and India. Whether medieval patrons and sculptors understood the difference between the two types of alabaster remains unclear. It is nevertheless evident that alabaster’s close connection to marble lasted through the middle ages.
In fact, one recipe in our manuscript seems to be making this connection as well. On fol. 101r-101v, a recipe for “sel a fayre fondre” (salt for founding) describes the process of making a modeling material out of salt and saltpeter that, when ground and heated, will make “une matiere blanche dure & unie comme albastre dequoy tu pourras jecter medailles qui sembleront marbre” (a white, hard and and uniform matter, similar to alabaster, from which you will be able to cast medals which will look like marble). Here, the resulting material looks as white as alabaster, and will create objects that look like marble. The two terms seem almost interchangeable. Interesting in the case of this manuscript is that the author-practitioner also makes clear reference to alabaster’s relationship to plaster. Lipinska states that alabaster’s chemical relationship to gypsum was not widespread knowledge before the early eighteenth century,36 yet the working knowledge of our author seems to indicate that the connection between alabaster and the “raw stones”37 of plaster was indeed a part of artisanal knowledge by the end of the 16th century. This acknowledgment could perhaps broaden our understanding of marble’s early modern taxonomy, as connected both to alabaster and to plaster. Although, it seems that Theophrastus’ third century BC De Lapidibus makes the connection between gypsum and alabaster, as he refers to an earth called gypsos, and a stone called alabastrites that can be found within this earth, both of which give off “stickiness and heat, when…wet,”38 after having been burned. He states that it is “used on buildings and is poured around the stone or anything else of this kind that one wishes to fasten.”39 He even mentions that painters in Italy use it for their art (ground alabaster and gypsum are still used in the preparation of gesso today).40 Theophrastus clearly refers to gypsum plaster here, and distinguishes the hard stone form of it as alabastrites. We can therefore understand the continuum of marble, alabaster and plaster that our author-practitioner is experimenting with as ancient mineralogical knowledge.
Thus, if we consider that our author-practitioner was interested in the materials he chose for their known properties, it would make sense that alabaster, as an elite stone closely associated with marble and celebrated for its ability to produce luminous and delicate carving in a sacred and commemorative context, would be assumed to have some finer and more “excellent” properties for molding than the much more easily attainable plaster, which was not used for art objects of as high status and caliber as its chemical counterpart. Moreover, the symbolic and biblical connotations of the material, connected to the transformation of the bodies of the faithful through resurrection, could have held special interest for our author-practitioner. His interest in transformation of materials is clear in his many experiments. Therefore, it is perhaps this symbolic potency of alabaster that leads the author to assume that it produces more “excellent” sand than plaster. This raises the question of whether our author had actually experimented with this sand, or was simply imagining that it would be a fine material. When comparing this recipe or the recipe using ox bone and rock salt with certain other recipes, such as that for “sand, for the most excellent lead of all, for large and small reliefs” on fol. 84v, or that detailing “sand experiments” on fol. 85v, the difference in rhetorical style is striking. While the alabaster recipe and the ox bone recipe have relatively clear, step-by-step instructions in declarative statements and certain specific ratios of materials, they do not have any of the narrative flair of the two recipes on fols. 84v and 85v. These recipes give full accounts in the first person of the processes attempted, and include descriptions of failures as well as successes.41 He makes note of changes in his technique over time and new knowledge he uncovers.42 Why would he insert such copious detail in some recipes and relatively little in others? We might take this to indicate that he had actually attempted certain sand recipes, and others he was merely collecting, perhaps for posterity, perhaps for later experimentation. Thus, the use of alabaster was perhaps merely a thought experiment, based on the prized properties of the material for sculpting, that the author-practitioner predicted might translate well to mold-making when incorporated into the typical sand paradigm of finely powdered substance mixed with a binder. It is certainly a functional sand, but perhaps no more “excellent” than others.
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Theophrastus. On Stones. trans. Earle R. Caley and John F.C. Richards (Columbus: Ohio State
University, 1956).
Wang, Yijun. “Fol. 89r, Powder of Ox Bone and Rock Salt.” Fall 2014.
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1 Franz Wirsching, “Calcium Sulfate,” in Ullmann’s Encyclopedia of Industrial Chemistry (2000), accessed April 20, 2015, doi: 10.1002/14356007.a04_555.
2 This note, written in the same hand but a different ink, appears next to a recipe for plaster molds to cast with wax. A cross appears at the head of this note.
3 See for instance Biringuccio, Pirotechnia, trans. Cyril Stanley Smith and Martha Teach Gnudi (New York: Dover Publications, Inc., 1990), pp. 218-220; Girolamo Ruscelli, The secrets of the reuerend Maister Alexis of Piemont, trans. William Ward (London: Peter Short, for Thomas Wight, 1595), fol. 105-106; Benvenuto Cellini, The Treatises of Benvenuto Cellini On Goldsmithing And Sculpture, trans. C.R. Ashbee (Whitefish, MT: Kessinger Publishing, 2006), p. 112.
4 Yijun Wang, Fol. 89r, “Powder of Ox Bone and Rock Salt,” Fall 2014.
5 Hugh Plat, The Jewel House of Art and Nature (London: Printed by Bernard Alsop, 1653), 194.
6 Perhaps the same substance as our manuscript’s “spalt.”
7 Georg Kremer, “Gips, Gispspat, Calciumsulfat,” on Kremer Pigmente, accessed May 4, 2015: http://www.kremer-pigmente.com/media/files_public/gips.pdf.
8 Fergus Cannan, “‘If Marble will not Serve’: Medieval English Alabaster Sculpture, from Quarry to Object of Devotion,” in Object of Devotion: Medieval English Alabaster Sculpture from the Victoria & Albert Museum, ed. Paul Williamson (Alexandria, VA: Art Services International, 2010), 22.
9 Fol. 83r
10 Fol. 83r
11 Fol. 83r
12 A comparison with commercially calcined bone and oyster shell revealed that some powders are so fine that it is hard to register contact with the surface of the material by touch. This seems to be the indication for what a truly “impalpable” sand should feel like. The manuscript references impalpability in a variety of recipes concerning the many formulas for sands for casting, on fols. 42v, 68v, 69r, 87v, 88v, 89v, 90r, 90v, and 92v. It is logical for such “impalpability” to be desired, as the finer-grained the mold material, the clearer and more precise the cast impression would be.
13 Fol. 89v
14 Fol. 83r
15 A later trial resulted in a fair amount of alabaster that had to be thrown away because the water was added too quickly and the whole amount of powder grew warm to the touch and began to harden, the same exothermic reaction that occurs when mixing plaster. We came to the conclusion that time is needed for the transformation of this material to take place, as slow humidifying allows for salt crystals to grow and bind the material, preventing an exothermic reaction resulting in the formation of hardening plaster.
16 The appropriate consistency for sand is described by Biringuccio as follows: “When [the sand] has been made as desired in this way it is moistened again before use with water, urine, or vinegar just enough so that it holds together when it is squeezed in the fist. Then, when it has been brought to this point, it is moulded as you will hear.” Biringuccio, Pirotechnia, 34. In Ms. Fr. 640, on fol. 118v, the author describes moistening the sand “in order to give it a nice hold, though it still came apart easily” (de facon quil faisoict bonne prise sesmiant toutesfois aisement). See also the Fall 2014 annotation by Cataldo and Visco on “Sands and Binders.”
17 The author-practitioner describes his own use of charcoal as a separator in box molds on fol. 118v: “Jay saulpoudre ma medaille avecq du charbon pulverise avec une lime” (I sprinkled my medal with charcoal pulverized with a file).
18 We were using a very dry pine wood box mold, and by placing it too close to the heating element of the toaster oven, the dry wood caught fire and was promptly extinguished.
19 We were later informed that proper technique would have been to remove the models immediately before leaving the molds to dry. This could have negatively affected the final quality of our casts. Unfortunately, this fact was not specified anywhere in our recipes, or in the manuscript, and had not been made clear to us in our workshop setting. A new attempt at this procedure removing the models right away could possibly yield different results.
20 Again, retrying this experiment removing the models right away might yield stronger impressions. It would also make sense to retry the experiment casting the same object in sands of different compositions, to be able to compare more directly.
21 Cannan,”If Marble Will Not Serve,” 26
22 For a thorough overview of the production and dissemination of these objects, see Paul Williamson, ed. Object of Devotion: Medieval English Alabaster Sculpture from the Victoria & Albert Museum (Alexandria, VA: Art Services International, 2010), the most recent and thorough treatment of this corpus of objects.
23 Aleksandra Lipinska notes a similar reverence for material in alabaster sculptures of the Low Countries and Germany. See Aleksandra Lipinska, “Alabastrum, id est, corpus hominis. Alabaster in the Low Countries Sculpture, a Cultural History,” Netherlands Yearbook for History of Art 63 (2013): 86.
24 Sophie Jugie, The Mourners: Tomb Sculptures from the Court of Burgundy (New Haven: Yale University Press, 2010), 36.
25 Sculptor Claus de Werve died in 1439 before completing the tomb of Duke John the Fearless due to inability to find a suitable source of alabaster. See Jugie, The Mourners, 46.
26 In the recipe on fol. 89v that also addresses alabaster sand, he specifies that upon drying, the mold will be “hard as stone,” (il vient dur comme pierre) which makes the cast easier to remove from the mold.
27 St. Augustine, Tractate: “Alabastrum unguenti, corpus est fidelis animae; fractum vero alabastrum, carnale est desiderium quod frangitur ad caput, ex quo omne corpus Ecclesiae compaginatum est.” Cited in Lipinska, “Alabastrum,” note 63, 109.
28 St. Jerome, Commentary on Matthew: “Mulier, id est, futura Ecclesia: alabastrum, id est, corpus hominis: per unguentum, ostendit fidem confessionis.” Cited in Lipinska, “Alabastrum,” note 62, 109.
29 Lipinska, “Alabastrum,” 99.
30 Ibid. 99.
31 Jugie, The Mourners, 119.
32 Lipinska, “Alabastrum,” 101.
33 Aristotle describes marble as a sort of permanently frozen water, condensed from the earth’s exhalation of vapors and frozen deep underground. Marble retained close associations to ice and water through the middle ages. See Fabio Barry, “Walking on Water: Cosmic Floors in Antiquity and the Middle Ages,” The Art Bulletin 89.4 (2007), 627-656.
34 Pliny the Elder, Natural History Book XXXVI, trans. D.E. Eichholz (Cambridge: Harvard University Press, 1962), accessed May 15, 2015: http://www.loebclassics.com.ezproxy.cul.columbia.edu/view/LCL419/1962/volume.xml, 49.
35 Isidore of Seville, Etymologies, trans. Stephen A. Barney (New York: Cambridge University Press), 321.
36 Lipinska, “Alabastrum,” 102.
37 As he refers to them on folio 106v.
38 Theophrastus, On Stones, trans. Earle R. Caley and John F.C. Richards (Columbus: Ohio State University, 1956), 59.
39 Ibid. 59.
40 Ibid. 60.
41 For example, on fol. 85v: “I made another cast with frying pan material alone, in the same sand, but not as reheated. It did not come out well.”
42 See fol. 84v, where he lays out the initial process for making sand from lead white bound with egg whites, then begins a new text block with “Since that moment, I have realized that even though this sand is excellent…it is fat and it makes bubbles.”