Stucco molding


Table of Contents

Stucco molding
Name: Reut Ullman, Carl Micheal Garris, and Sumeyye Yar
Date and Time: 2017.10.16, 1:20pm - 215-20 pm.
Location: 260 Chandler
Subject: Making stucco

Stucco making and moulding
Ingredients
6 g of tragacanth gum
60 ml of water
18 g. of chalk + more

Equipment
2 beakers
Mixing bowl
Sieve
Glass board
Muller

To make stucco, we used a recipe found in Ms. Fr. 640 29r, which instructed: "Take tragacanth gum and put it to soak until, having drink its water, it is swollen & rendered like jelly. Then crush it quite hard on the marble & next take rye flour, which is better than wheat because it is more humid and does not make the paste as brittle, and sprinkle your tragacanth gum with it, & continue to grind and mix in thus, little by little, the very finely sieved flour. And knead it as if you wanted to make bread until you perceive that it has enough body & is as firm as bread dough that one is ready to put in the oven. This is perceivable when it can stretch enough without breaking. And if it as not strong enough, it would not release well…”

The recipe continues with instruction for the moulding process, to be mentioned later, and then gives another stucco recipe using plaster, which calls for a 15-day drying period. Pressed for time, we chose the first recipe, but instead of using rye flour, as the recipe called for, we used chalk, as the author practitioner advised, on the top left marginalia near the flour recipe, the use of chalk or ceruse instead of flour: “the flour is not good in this, but chalk or ceruse is.”

The class broke into two teams, we were the chalk team. Woo! Knowing that chalk is a very dry, water absorbent material, we thought that we would not require much of it. We were wrong, well almost. As the recipe did not indicate measurements, we followed the ratio (1:10 gum to water; and 1:3 gum to rye flour) used by Sophie, whose earlier attempts at the recipe proved successful. However, unlike Sophie, we needed to turn out a minimum of 9 figurines, she had made 3-4. Sophie had used 1 g. of gum to 10 ml of water, to 3 g of flour or so. We adjusted the recipe to 6 g. of gum, 60 ml of water, and 18 g of chalk.

We began by slowly coating the gum powder with water, which it dutifully absorbed, forming clumps. The clumps resisted the mixing attempts at disintegrating them, which necessitated the use of another tool to physically smash them. Once having achieved the desired qualitative state of jelly, as instructed in the recipe, we transferred the mixture onto a glass slab, and began to mull it, while adding drops of water. Despite water additions, the mixture was sticky, and the mulling difficult. Once we had emptied the contents of the water beaker, we decided to add more, I didn’t note the exact amount, but we more or less played it by ear. Having mulled azurite and madder lakes, we knew to continue mulling and adding water until the mulling grew progressively easier, the movements softer, and the mixture having completely surrendered to the muller. Once this has been achieved, around 1:43 pm, we measured out 18 g of chalk (following Sophie’s ratio), and using a sieve, gently sprinkled the sieved chalk, coating our gum mixture, all the while continuing to mix it, now by hand. We had used the entire 18 g of chalk, but found the gum mixture nowhere near the desired solidity, it was very sticky, incapable of forming any shape, either sticking to the fingers and hands or the glass board. We proceeded to add, another 18g, still much the same, then another 18.5 g, nothing, then another 20 g. By the time we hit the end of our 4 chalk additions, the paste took on more body, it was very sticky, but showed promise. We added another 17.2 g, and at this point, it grew less sticky, heavier, and capable of forming a shape, but did not pass the stretching test outlined in the recipe. Growing impatient, we decided to use a small amount to try moulding, but as the recipe had predicted, the mould would not release, and we added another 19.6 g of chalk. After this addition, the paste was no longer sticky, it was easy shaped into a ball, much like oven-ready dough.

Initially we had thought we would need much less chalk, as chalk is heavier and drier than flour. When we saw that more additions were required, we were surprised and only hesitantly and cautiously added more. However, once swapping notes with the rye flour team, we found that we had in fact used less chalk than they had flour. Our starting quantities were the same. Thus, chalk is in fact dryer than flour, and absorbs more water than flour, even though it behaved not as we had initially expected.



Name: Reut Ullman, Carl Micheal Garris, and Sumeyye Yar
Date and Time: 2017.10.16, 2:00pm
Location: 260 Chandler
Subject: Moulding with stucco


Ingredients:
Linseed oil

Equipment:
Rubber moulds (several different sets)
Cup, cut in half
Brush

The author practitioner of the manuscript Ms. Fr. 640 29r provided instructions for moulding:
“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. And if it does not release well, mix in more flour until it has enough body. With this you will mold whatever work you like, masks or garlands, which will be dry within one day.”

Using a brush, we generously coated the cavities of our mould sets with oil, and proceeded to press the paste in, as directed by the recipe. Each mould was removed less than 30 seconds after being pressed in, and each time the mould emerged easily, lifting fine details. We had initially tried simpler designs, not confident in our stucco potential. However, earlier the same morning, the lab had received a set very detailed, all in the shape of various angels. Against naysayers, and unbelievers, we tried the angel moulds, and turned out several beautifully shaped, highly detailed figurines, which perfectly demonstrated the malleability of our chalk based stucco. This realization, for me personally, seemed a little surprising because once we added more chalk, indeed the more chalk we added, the denser and less pliable, or mouldable, the paste seemed to become, but once fitted into the moulds, it easily adapted to the carved cavity, and lifted its shape and details.

All in all, our stucco moulding exercise yielded 14 moulds. Success!
As per instructions, we attached 3 moulds to a rounded surface, a cup cut vertically in half, and let them dry. The rest of the moulds were left to dry on a flat surface, a plate.

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Name: Reut Ullman, Carl Micheal Garris, and Sumeyye Yar
Date and Time: 2017.10.17, 6:00m
Location: 260 Chandler
Subject: Coating with gesso and glue


Ingredients
Water
Rabbit skin glue
Chalk

Equipment
Pot
Hot plate
Chopstick
Funnel
Sieve
Spoon
Scales

After having moulded with stucco, and let the moulds dry, as per instructions in Ms. Fr. 640 29r, the author practitioner instructs the readers to coat the moulds: “next, you will apply them with strong glue or paste glue, as you like and will be able to paint and decorate them with gold & all colours.”

Our group was to make gesso, a rabbit-skin-based glue, while the other group made glue-glue (full disclosure: I am not really sure what they made, I was spacing out when instructions were given)
We prepared the gesso according to instructions laid out in Cennino Cennini’s The Craftsman’s Handbook.
Using a hot plate, which was set on minimum heat, we heated a pot with water into which was placed a jar of rabbit-skin glue (smelled just awful). Once the glue liquefied, in a separate beaker, we measured out 35.6 g. of chalk, on Jo Kirby’s instructions, and using a sieve we sprinkled chalk, spoon by spoon, slowly. The recipe advised against stirring for fear of bubble formation, which will then transfer onto the canvas and ruin the aesthetics of the work. However, on noticing that the glue was not absorbing the chalk, but merely pushing it to the bottom, we threw aesthetic considerations to the wind, and stirred away. Our stirring was gentle, but consistent. And bubbles did indeed form, but were likely the result of rabbit glue resisting the chalk rather than our enthuastic stirring. We continued to sprinkle chalk, coating the surface of the glue, and seeing the chalk only ever push to the bottom, layering the floor of the beaker. After some time, I didn’t note how long, a change had occurred, the mixture turned from a dull shade of wax to a very light grey. Naomi had felt the mixture thicken on stirring, but this was not a uniformly shared feeling. We tested the readiness of our gesso by lifting the stirring chopstick and seeing if the gesso residue would remain, or trickle down, as it had done minutes earlier. Once we saw the residue sticking, with only a slight movement of an upper layer of liquid slowly descending down the tip of the chopstick but not actually dropping, we deemed our gesso ready for use. We ended up using only 16.64 g of chalk.

Using flour glue, we attached our moulds to different surfaces, which were either primed with gesso or bare, to test the strength of the glue on different surfaces. We attached 4 mould figurines to a rounded surface, a vertically cut cup; 5 to a linen canvas primed with rabbit glue; 3 to an unprimed Masonite (MDF); and 2 to a gesso primed Masonite (MDF).

We then proceeded to coat some mould figurines with rabbit glue, some with gesso, and some with a coating of rabbit glue and then gesso, which were left to dry.

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ASPECTS TO KEEP IN MIND WHEN MAKING FIELD NOTES