[Stucco fol. 29r_1]
Table of Contents
Date and Time:
2017.[November].[27], [11]:[00][am]
Location:Subject: Recording stucco work in the lab (fol. 29r_1)
<div>
<id>p029r_1</id>
<head><m>Stucco</m> for molding</head>
<ab>Take <m>tragacanth gum</m> and put it to soak until, having drunk its <m>water</m>, it is swollen & rendered like <m>jelly</m>. Then crush it quite hard on the <tl><m>marble</m></tl> & next take <m><pa>rye</pa> flour</m>, which is better than <m><pa>wheat</pa></m> because it is more humid and does not make the paste as brittle, and sprinkle your <m>tragacanth gum</m> with it, & continue to grind <add>and mix in</add> thus, little by little, <del><fr>le et mesler legi</fr></del> the very finely sieved <m>flour</m>. And knead it as if you wanted to make <m>bread</m>, until <del>you</del> you perceive that it has enough body & is as firm as <m>bread dough</m> that one is ready to put in the <tl>oven</tl>. This is perceivable when it can stretch enough without breaking. And if it was not strong enough, it would not <del><fr>sti</fr></del> release well. Thus once prepared, rub the cavity <del><fr>au u</fr></del> with <m>oil</m>, with a <tl>brush</tl>, so that the <m>oil</m> penetrates everywhere to make it release better, and press the paste inside quite hard. And if it does not release well, mix in more <m>flour</m> until it has enough body. With this you will mold whatever work you like, masks or garlands, which will be dry within one <ms>day</ms>. Next, you will apply them with <m>strong glue</m> or <m>paste glue</m>, as you like, and you will be able to paint and decorate them with <m>gold</m> & all colors. In <pl>Rome</pl> they make ceiling and wall ornaments with it. One can make bed ornaments with it. <rub>If you want that the work stays white</rub>, it is better to mold with <m>plaster</m> instead of <m>flour</m>. It is true that it is more brittle and firm as well, but one needs to prepare it like this: temper it, when it is powdered <del>strong</del>, in a good amount of <m>water</m> so that it is <add>clear</add>, & grind it several times a day for fifteen <ms>days</ms>. Then pour <m>water</m> at an angle, and gather the <m>plaster</m> & grind it finely on the <tl><m>marble</m></tl>, & place it in some kind of clean <tl><m>lead</m> vessel</tl>, so that no dust & dirt falls into it, & leave it <env>in the open air</env> &<env><fr>au serain</fr></env> for fifteen <ms>days</ms> with its <m>water</m>, and it will become matte, strong, white and light, very suitable for making a groundlayer of burnished <m>gold</m>. And this, when powder, you can mix, instead of <m>flour</m>, with <m>tragacanth gum</m>, and your work will be very beautiful. Lacking <m>plaster</m>, you can mix in well ground <m>chalk</m> or <m>ceruse</m>, & try <m>bole</m> & similar things. This <m>stucco</m> with the <m>tragacanth gum</m> has the quality, being malleable before being dry, of fitting on either round or flat things, as you like. It is to make an ornament at little expense.
</ab>
<ab>
<margin>left-top</margin>
The <m>flour</m> is not good in this, but <m>chalk</m> or <m>ceruse</m> is.
</ab>
</div>
As the author-practitioner’s recipe does not include measurements, I readied the ingredients and prepared to make experiential guesses. The processes for using rye flour, wheat flour, chalk, and plaster of Paris were very similar, as they all began with tragacanth gum, but each ingredient revealed different properties which informed our understanding of the author-practitioner’s method. Also, we recreated the first part of the recipe, and did not recreate the 30-day process, mostly due to time constraints. The 30-day process was most likely a method of preparing slaked plaster. The plaster of Paris used in this reconstruction was un-slaked.
As per the author-practitioner’s instructions, I added each of the powdery, primary ingredients to the tragacanth gum jelly gradually. Please refer to table 1for observations about each ingredient during and after the molding process. I used a wooden mold, carved in intaglio, which was meant to be a German springerle cookie mold, and a metal cookie stamp, also carved in intaglio.
I used tragacanth gum powder, which “soak[ed] until, having drunk its water, it is swollen and rendered like jelly.” The gum requires a significant amount water to reach this state; approximately, 13 ml of water must be added for each gram of tragacanth gum.
It must then be “crushed quite hard on the marble,” to make the jelly smooth—insufficient mixing leads to lumps in the mixture, which could have detrimental effects on the final product. For example, it could affect the texture and appearance, as well as the integrity of the mixture. Moreover, adding the water too quickly to the gum resulted in a lumpier texture and made it more difficult to blend the water and the powder.
The author-practitioner emphasizes the way the flour must be sieved and added gradually: “Then take the rye flour [...]and sprinkle your tragacanth gum with it, and continue to grind and mix in thus, little by little, the very finely sieved flour.” Rye flour includes impurities from the rye, such as chaff or bits of the seed casing, which need to be sieved out to improve the stucco’s texture. Wheat flour, chalk, and plaster of Paris, however, do not contain those impurities. Moreover, the flour does indeed need to be added gradually, for the same reason that the tragacanth jelly has to be “crushed.” Adding the powdery substances too quickly led to lumps and an uneven texture. This makes the process rather slow—for each batch of stucco, it took about 30 minutes of gradually adding the flour or chalk etc. to get to the mixture to a state where we could it could be handled as a cohesive mass. To mix it effectively, I used metal palette knives, scraping and combining the gum and powder together. Counterintuitively, this was better than using my hands. If I used my hands before the mixture was cohesive enough, it would mercilessly stick to them and make it very difficult to mix the ingredients. Brief experimentation with plastic palette knives showed that those were even better at incorporating the powders with the tragacanth gum, however for the sake of historical accuracy I stuck to using the metal palette knives.
Photos of the wheat flour
Next, the author-practitioner advises to “knead it as if you wanted to make bread, until you perceive that it has enough body and is as firm as bread dough that one is ready to put into the oven. This is perceivable when it can stretch enough without breaking. And if it was not strong enough, it would not release well. [...] And if it does not release well, mix in more flour until it has enough body.” This again indicates the tactile quality of the author-practitioner’s instructions, similar to other entries in the manuscript.* Through reconstruction, we realized that the author-practitioner emphasizes both plasticity, meaning that the mixture can be handled and stretched without being too brittle, and cohesiveness, meaning that the mixture will not stick to the mold and be too gloopy to take the molds’ shape.
Keading the plaster of paris
Kneaded the rye flour
The author-practitioner indicates that the molds should be oiled before applying the mixture: “Thus, once prepared, rub the cavity with oil with a brush so that the oil penetrates everywhere to make it release better, and press the paste inside quite hard.” The author-practitioner does not specify what kind of oil. Given this lack of specificity, it is most likely the exact type of oil was either irrelevant, or obvious. We used linseed oil, since it was readily available to us in the lab. The author-practitioner says that the resulting product will be dry within one day, which we found to be true (mostly). He then describes how to prepare the stucco for painting, but that was beyond the scope of this reconstruction. The author-practitioner mentions that plaster, chalk, white lead, or bole can be used instead of flour, and adds later that flour should be avoided if possible.
Oiling the mold with linseed oil
The first batch of flour stucco I made was too little, meaning the imprints were too thin. Though the rye flour mixture fared a bit better, they both cracked
Readying the plaster of Paris stucco, and the results.
Freshly imprinted chalk stucco.
While tragacanth gum does not appear in other contemporary stucco recipes, the author-practitioner explains that “this stucco with the tragacanth gum has the quality, being malleable before being dry, of fitting on either round or flat things,” and is apparently an inexpensive method of creating ornaments. The author-practitioner’s recipe did result in very malleable, manageable stucco, well-suited for small, ornamental molds. Also, oiling the molds in advance uniformly resulted in a clean imprint with no residue left on the molds.
Recreating the recipe helped shed light on the author-practitioner’s understanding of the materials. The wheat flour stucco took the imprint well, but after a week of drying, had inflated as if it was bread rising. Moreover, it had not dried fully; the side that had been resting on the plate was still sticky, and the inside of the stucco was damp as well.
Inflated/swollen wheat flour stucco
After a week, neither the wheat nor rye had dried.
The inflation had distorted the imprints. The rye flour mixture was also slightly damp. In both cases, the dampness indicates the stucco would be susceptible to rot if not dried properly before being affixed to a surface. We had to put both in the fume hood to speed the drying process, after it had been left to dry in the lab for a week. The stone-based ingredients dried well. Chalk produced a fine, white stucco, but it showed evidence of slight cracking on the surface over a week of observation. Plaster of Paris proved to be the best material for producing good, sturdy, well-textured stucco, as the imprints held with no distortion, nor did the stucco show signs of cracking. It would be interesting to attempt this reconstruction with slaked plaster of Paris to see if there is a difference.
Chalk and plaster of Paris stuccos.
For each batch, we used:
1.25 tsp of tragacanth gum (4.10 grams)
55 ml of tap water
(the ratio of tragacanth gum to water which results in a jelly once well mixed was 1 gram of tragacanth gum to approximately 14 ml of water)
For each ingredient, we stopped adding the primary molding ingredient when the mixture was adequately malleable yet firm.
Table 1:
| Stucco for molding: primary ingredient |
Quantity used ( grams) |
Observations |
Results |
| Rye Flour (sieved) |
83 |
Once enough flour is added, reaches a tough, but still bread-like texture; dried quickly if not being handled |
Brown, gritty stucco |
| Wheat Flour |
107 |
Extremely soft and yielding |
Brittle |
| Chalk |
95 |
Tougher texture when handling |
Good imprint |
| Plaster of Paris (straight from the tub, unslaked) |
150 |
Looked like crumbly ricotta cheese, it was very pillowy but dried quickly if not being handled |
Very good imprint |
- Please see Emma Le Pouesard's annotation "Pain, Ostie, Rostie: Bread in the Early Modern Period," on the descriptive qualities of bread in the manuscript:
Name: Nina Elizondo-Garza
Date and Time:
2017.[December].[17], [11]:[00][am]
Location: LabSubject: Addendum about wheat stucco
At the end of the semester, I catalogued my finished molds in accordance with lab protocol. Before this, each molded stucco had sat on a countertop in the temperature-controlled lab. The chalk and plaster of Paris stuccos were fine and looked the same. The rye flour stucco was brittle and cracking slightly, but in passable condition. The larger wheat flour stucco mold, however, fell apart in my hands when I tried to lift it to put it in a bag for cataloguing.
The smaller pine tree mold fared better but was still very brittle. This month-long time lapse demonstrates the different qualities of each of the ingredients, and corroborates the author-practitioner's claim that wheat flour should not be used.