Tag Archives: reconstruction

True Colors, or the Revelatory Nature of Cold

By Thijs Hagendijk

Heat is transformative, brings about change, separates substances or bring them together. Every student of chemistry knows how to enable or enhance a chemical reaction by applying energy to a system, usually in the form of heat. Early modern practitioners did not think otherwise. Fire was the transformative element and key to the production of all kinds of different materials, ranging from the philosopher’s stone to artisanal products such as glass, porcelain or pigments. Applying heat to bring about change is publicly ingrained thermodynamics, but one thing is even more obvious. Once heated, things have to cool down again.

Figure 1: Eikelenberg’s notes on the art of painting, comprising five different manuscripts. Photograph: Regionaal Archief Alkmaar.

When the request came to write a blogpost on cold and recipes, I was somewhat hesitant. Heat seems to elicit the most interesting stories and anecdotes, but interesting cases with respect to cold failed to come to mind immediately. Hence, I tried a different approach and looked at how cold featured in a collection of overtly practical notes on the preparation of paint materials collected by the Dutch polymath and painter Simon Eikelenberg (1663-1738). Intended for publication, he promised his readers an “accurate descriptions of the origin of making, preparation and general use of paint materials, oils, mix-fluids and varnishes.”[1]  It was within the confines of this manuscript that I began to discern two themes with respect to cold in practices of making.

Figure 2: Reconstruction of one of Eikelenberg’s varnish recipes. The varnish was prepared in a glazed pot, placed in a sand bath and heated on fire. Photograph: Thijs Hagendijk.

It is only when things have cooled down that the transformative work of heat can really be judged. Eikelenberg describes for instance how he experimented with minium, a red lead-based pigment, which he heated in a crucible and placed in a fire. “The more it glowed, the more the minium turned yellow near the sides of the crucible, the lowest parts alike; which, when it was cold, appeared to be nothing else but yellow massicot.” [2] Eikelenberg also describes the preparation of various varnishes. Here too, quality and properties of substances are explicitly observed after the varnishes have cooled down. “When the varnish was cold I found that it was rather thin and that it did not cover well.” [3]  Another varnish was prepared on a hot sand bath, after which Eikelenberg “filtered it through a cloth and let it cool: it appeared then as a thickish and yellowish varnish.” [4]  Pay attention to the word “then”: there is a clear order of things that speaks through Eikelenberg’s notes. Being cold is a condition that precedes testing and Eikelenberg makes that rather explicit.

Figure 3: It is hard to achieve a homogeneous mixture when preparing varnishes. A whitish sediment is developing in this varnish, which is in coherence with Eikelenberg’s notes. Photograph: Thijs Hagendijk.

Whereas heat is transformative, it is only in the absence of heat that things can be trusted to stay the same. Continuing with the varnishes, Eikelenberg was well aware that their preparation does not stop after the ingredients have been heated and combined. As long as it is still hot, the apparently homogeneous concoction can easily coagulate and fall apart. Eikelenberg wrote in his notes: “We can conclude that to prevent curdling it is necessary not to stop stirring before the mixture is cold.” [5] Indeed, each time he made varnishes, Eikelenberg made sure to keep stirring until everything was cooled down: “stirring steadily until all was cold” or “having stirred until it became cold”.[6]

Figure 4: Eikelenberg mentions that: “[w]e can conclude that to prevent curdling it is necessary not to stop stirring before the mixture is cold.” Passage marked in red. Photograph: Regionaal Archief Alkmaar.

For Eikelenberg, heat was both friend and foe and until his varnishes reached firm, cool ground, they required careful guidance and attention. Cooling down was thus as arduous a process as heating the mixture was in the first place. Yet, once cooled down, true colors are revealed – deprived from heat and stabilized by the cold.

[1] Simon Eikelenberg, “Aantekeningen betreffende schilderen,” MS 391, Collectie Aanwinsten, Regionaal Archief Alkmaar: fol. 1. “Naukeurige beschrijving van de oorsprong of making, bereiding en ’t algemeen gebruik der verfstoffen, olijen, mengvogten en vernissen.”
[2] Simon Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, Collectie Aanwinsten, Regionaal Archief Alkmaar, fol. 806. Original: “na mate dat het gloejend wierd, veranderde de menij die naast tegen de zijden van de kroes aan-zat en wierd geel, gelyk ook ’t onderdtste; ‘t welk doe ‘t kout was niet anders dan gele masticot geleek”.
[3] Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, fol. 827. Original: “Doe de vernis koud was bevond ik ze wat dun en datze niet genoeg dekte.” Translation from: A. van Schendel, “Simon Eikelenberg’s Experiments on the Preparation of Varnishes,” Studies in Conservation 3 (1958), 130.
[4] Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, fol. 802. Original: “Doe ‘t wel vermengt was, kleijnsde ik ‘t door een doek en liet het kout worden, wanneer ‘tzelve een dikagtige en geelagtige vernis vertoonde” Translation from: Schendel, “Simon Eikelenberg’s Experiments,” 128.
[5] Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, fol. 824. Original: “Hieruijt kan men afnemen dat om ’t schiften voor te komen, men niet moet op-houden met roeren voordat se kout is.” Translation from: Schendel, “Simon Eikelenberg’s Experiments,” 129.
[6] Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, fol. 827. Original: “gestadig omroerende totdat het gantschelijk koud was.” Translation from: Schendel, “Simon Eikelenberg’s Experiments,” 130. Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, fol. 832. Original: “tot koutwordens toe geroert te hebben”.

 

Boiling hot oil: on the assessment of temperature in late medieval processing of linseed oil

By Indra Kneepkens

Indra Kneepkens is a technical art historian, specializing in the materials and techniques of late medieval panel painting. She is currently finalizing her dissertation, which is focused on the use of processed linseed oils and paint additives in the painting practice of the fifteenth and early sixteenth century.

Raw linseed – the basis for linseed oil

From art technological sources, such as recipes and manuals for the preparation of paints, and from the analysis of paint samples, we know that late medieval and early modern craftsmen heated oils for use as a binding medium in paints, as well as for the preparation of varnishes. As a technical art historian, I research and reconstruct these oils and varnishes, to be able to establish the effects they have on paints. My aim is to understand how the development and use of these materials influenced the painting process and the final appearance of art works. Unfortunately, 14th-  to 17th-century art technological sources that include heat-treatment of oil typically do not give absolute temperature indications. This is no surprise, because thermometers were developed in different stages between the late 16th and early 18th century. Therefore, craftsmen had to rely on their senses for the assessment of temperature.

Cennini’s handbook has been transcribed an translated repeatedly, most recently by Lara Broecke in 2015

That controlling temperature was important to late medieval craftsmen is illustrated by a remark in the Libro dell’arte (ca. 1390), that was written by the Italian painter Cennino Cennini. In his recipe for a heat-treated oil the writer almost personifies fire, warning us that it would willingly burn down the house if it got a chance to reach into the pan.[1] And indeed, it seems likely that the temperature of oil was sometimes raised pretty high, to the point where potentially explosive gasses form. So how did pre-thermometer craftsmen determine the temperature of their oils?

Even if not in absolute terms, early modern sources do contain clues about the kind of temperatures that were considered useful in oil processing. In most cases, oils were heated over fire, in ceramic, bronze or copper vessels. As wood or peat fires can easily reach temperatures over 500°C, and the vessels were able to withstand these, it was clearly possible to reach the auto-ignition point of linseed oil (ca. 343°C). Most likely, temperature would have varied from case to case, depending on factors like fuel type and the distance between the vessel and the heating source.[2]

Sometimes sources mention a strong reduction of the oil, or they describe the texture of the end result, comparing it to fluid honey for example. In varnish recipes a string-test reoccurs, in which a finger is dipped into, and then lifted from a cooled drop of the mixture of boiled oil and resins, to see if a thread is formed.[3]My own experiments have shown that to reach a sufficient thickening of an oil or varnish, and to dissolve most resins, the materials must be heated for quite some time and at a fairly high temperature. Finally, empirical tests that remind us of everyday cooking may have been used to keep an eye on the temperature of oils. In Arte de la Pintura (1649), Pacheco describes how bread, garlic and feathers were stuck in boiling oil; if they appeared browned or scorched, the cooking process was completed.[4]

During my experiments over the past few years, it has become evident that one can make a reasonably accurate temperature assessment based on how the oil behaves during heat-treatment. A swirling movement for example, was noticed in oils from a temperature of ca. 90°C, while repugnant fumes typically started to develop around 200°C.

Figure 1. Foam developing on oil heated in a ceramic vessel

I also realized that the development of foam, which is commonly mentioned in recipes, may have been a clear indication of temperature. But it is also closely related to the type of cooking vessel that was used. I did not see any foam until I exchanged my glass laboratory beakers for a glazed ceramic pot. Foam appeared when the oil reached a temperature of 100°C. It must have been caused by water evaporating from the clay body, as I had rinsed the vessel before use. Bubbles also formed when garlic and bread were boiled in oil, from ca. 61 and 80°C respectively, with a high point again around 100°C. Although the garlic started to darken earlier, both bread and garlic clearly browned around 180°C, and completely blackened between 230 and 240°C.

In another experiment thirteen feathers, of different size and from various birds, were dipped in hot linseed oil until they started to curl. Surprisingly, all feathers curled within a range of 27°C, between 237 and 264°C. These experiments not only support the relative accuracy of these empirical methods, but also indicates that temperatures of ca. 100 and 200-250°C were meaningful to early practitioners.

Figure 2. Raw linseed oil (far left) heated at 150 (1-4 hours, jars 2-5 from the left), 200 (8 hours, larger jar) and 300 degrees C (1-4 hours, jars 7-10 from the left).

In more systematic tests, linseed oil was heated to 150 and 300°C, for one, two, three, and four hours. Interestingly, the color and thickness of the oils that were heated at 150°C appeared more or less unaltered after the experiment. In tests where these oils were mixed into paints, they behaved very similar to raw linseed oil. At 300°C the oils thickened and darkened considerably. They affected paints in a very significant way, causing them to level, and making it possible to create smooth glossy films without any visible imprint of the brush. Paints with these oils were also less prone to yellowing. An oil that was heated at 200°C for eight hours however, still made paints level perfectly, but it also caused extreme yellowing.

So knowing how to assess temperature and balancing it over time must have been crucial skills for those who prepared heat-treated oils and varnishes. Experiments have shown that knowledgeable individuals would have been able to make a fairly accurate assessment of temperature, using their senses. They could note changes in the appearance and behavior of oil and indicator materials, and manually test its viscosity. Although there are several indications that temperatures of 200°C and higher were preferred, it makes sense that craftspeople would adapt the temperature to the materials at hand and the desired end result. The lack of unambiguous temperature indications in oil processing recipes reflects this adaptive use of temperature and a reliance on the senses that was expected of craftspeople before the invention of thermometers.

[1]Broecke, Lara. Cennino Cennini’s Il Libro dell’ Arte: A new English translation and commentary with Italian transcription.London: Archetype, 2015, 127, chapter 91.

[2]Aldeias, Vera, Harold L. Dibble, Dennis Sandgathe , Paul Goldberg, and Shannon J.P. McPherron . “ How heat alters underlying deposits and implications for archaeological fire features: A controlled experiment” Journal of Archaeological Science67 (2016): 66.

[3]Broecke 2015, 127. Neven, Sylvie. The Strasbourg Manuscript. A Medieval Tradition of Artists’ Recipe Collections (1400-1570). London: Archetype, 2016: 132-135, no. 92-94.

From the Hearth to the Gas Stove: A Study in Apricot Marmalade

By Marissa Nicosia

The early modern hearth and the modern gas stove are rather different technologies for controlling heat. Again and again in my recipe recreation work for Cooking in the Archives, I encounter complex instructions for managing cooking temperatures on a hearth and try to translate those instructions to my own equipment. To what temperature should I set my oven? How high should I turn up the flame under the pot? What volume of water should I add when boiling water is called for and no volume is specified? How long should everything cook?

Early modern recipes trust that cooks know their hearth and ingredients well. Some recipes are very precise about weight and volume and others read like general concepts on which a cook might improvise as best suits their needs, inclinations, or tastes. Cooking these recipes on a hearth with variable fire types and temperatures demanded a skilled cook who could manage heat effectively.

This is the part of updating recipes that most challenges me: I have a PhD in English, but no formal culinary training. This is also the part of updating recipes where I have been most challenged by others. Members of the historical reenactment and historical interpretation communities have in turn urged me to try these recipes again on a hearth to taste the different flavors the fire instills and chastised me for attempting to cook these recipes without a hearth in the first place. As I grow as a cook and expand this project, I’m going to accept these kind invitations to cook alongside skilled recreators [1]. But Cooking in the Archives is a project designed to give all readers a taste of the past: even if those readers possess only the tiniest apartment stove. That’s the kind of stove that I had in my West Philadelphia rental when I launched the site with Alyssa Connell in 2014.

In order to cook these recipes on my stove, I have to determine some basic information: Is this something I should make on the stovetop or in the oven? In a pot, pan, or roasting dish? Is the recipe asking for water and should that water be boiled first or with the ingredients? To answer these questions, I naturally start with the recipes themselves. The phrases recipe writers use for the ferocity or gentleness of the fire are subtle, but informative. Then I look at recipes in modern cookbooks. The “Jumball” cookie mix looked like a shortbread cookie so I started with the oven temperature from a familiar cookie recipe and kept track of the time [2]. These are skills that I learned from baking growing up and cooking for myself while I was in graduate school, but not, exactly, skills that I learned in the academy. Neither humanities course work nor historical recreation holds all the answers for how to, say, make an apricot marmalade from a late-seventeenth-century culinary manuscript in a twenty-first century kitchen.

This recipe “To make Marmalaid of Apricocks” is from Ms. Codex 785 at the Kislak Center for Special Collections, Rare Books, and Manuscripts at the University of Pennsylvania. I’ve prepared quite a few recipes from this specific manuscript, and this recipe, like a few others in the volume, derives from Hannah Woolley’s cookbook The Queen-like Closet or Rich Cabinet (1670) [3]. This marmalade is both fragile and delicious. It needs the careful tending outlined in the original recipe. I have attempted to convey this level of care in my updated recipe at the end of this post.

To make Marmalaid of Apricocks

Take Apricocks, pare them and cut them in
quarters and to every pound of Apricocks
put a pound of fine Sugar, then put your
Apricocks in a Skillet with half the Sugar
and let them boil very tender, and gently, and
bruise them with the back of a Spoon, till they
be like pap, then take the other part of the
Sugar, and boil it to a Candy height, then put
your Apricocks into that Sugar, and keep it stirring
over the ffire, till all the sugar is meted, but
do not let it boil, then take it from the ffire,
and Stir it till it be almost cold, then put it
into Glasses, and let it have the Air of the
ffire to dry it.

Images 1 & 2 – The recipe in Ms. Codex 785, 6-7

The recipe asks you to boil the apricots with sugar until the fruit is so tender that it breaks down into a luscious pulp. Then the recipe instructs you to make a simple syrup of sugar and water and allow the mixture to come to candy height or what we would now call the soft-ball stage. Early modern cooks would have been especially skilled at the subtle art of watching sugar change under the influence of heat. The cook is next told to stir the apricot puree into the hot sugar over the fire and then off the fire until the mixture is almost cold. The final instruction: “and let it have the Air of the ffire to dry it” is the most evocative image for me. The preserved apricots in glass containers glowing in front of the hearth.

This apricot marmalade is delicious on toast, lightly crisped by the heat of a toaster oven or toaster, of course.

 

An Updated Recipe

8 apricots (7 oz, 200 g)

generous 2/3 cup sugar (7 oz, 200 g)

1/3 cup water

Peel the apricots, remove their pits, and cut them into quarters. Cook them to a pulp with half the sugar. The apricots will release their own juices so no water is necessary here. (Approximately 10 minutes.)

Make a simple syrup with the remaining 1/3 cup sugar and 1/3 cup water in a saucepan. Use a candy thermometer to keep track of the temperature and cook until it reaches candy height/pearl stage 240F on the thermometer. When the syrup has reached this temperature, add the cooked apricots to it. Stir to combine over the heat, but do not allow the mix to boil.

Remove from heat and stir as the mixture cools. Transfer into a clean jar. This amount of apricots and sugar nicely filled an 8oz jelly jar.

Keep refrigerated and eat within two weeks. (You can also properly can this for longer storage.)

[1] Johnson’s work in particular suggests what traditional academics can learn by spending time with reenactors and participating in reenactments. Katherine M. Johnson, “Rethinking (re)doing: historical re-enactment and/as historiography,” Rethinking History 19, no. 2 (2015): 193-206.

[2] https://rarecooking.com/2014/09/19/my-lady-chanworths-receipt-for-jumballs/

[3] https://rarecooking.com/tag/ms-codex-785/

HEAT! A Recipes Project Thematic Series

Astronomy- the Earth and the sun during summer in the Northern hemisphere. Wellcome Collection.

As humans, we want to control heat. We want to create heat, temper or even extinguish it, depending on context and purpose. We have a very limited temperature range at which we are comfortable (some microbes and bacteria can survive temperatures as low as -20C and as high as 130C), so we spend an incredible amount of time managing heat, whether it is our body temperature or that of our homes, offices, laboratories, cars, or food.

When we started planning this series of blog posts in early May, we could not have suspected how appropriate the theme would feel by now. While much of northwestern Europe has not seen rain in weeks and is sighing under a heatwave with temperatures rising to 37C/98F, we have fled to airconditioned spaces to edit the posts. Climate-wise, heat is seasonal in these regions, but it has always played an important role in recipes year-round, all around the world, from antiquity to the present day, in fields as diverse as alchemy, chemistry, art, cooking, medicine, and personal grooming.

The common denominators of heat in all these realms are that it is either internal – emanating from the human body – or external, naturally occurring from the sun, thunder, or lava, or man-made through friction or fire. In the posts in this series, we will see a wide variety of attempts to control these different kinds of heat through recipes and instructions.

Managing natural heat: Venice turpentine is a thick paste (aka sticky mess) at room temperature, but becomes fluid around 25C, and nicely mixes into the rest of the varnish ingredients when left out in the sun. Photo: Marieke Hendriksen

Some of our authors recreate such attempts by reconstructing experiments outlined in historical art technical and chemical sources. Indra Kneepkens recounts how she discovered through reconstruction research that sometimes for a recipe to make sense, it should not only be followed to the letter, but also be read between the lines. Ruben Verwaal and Marieke Hendriksen use their experiments with two reconstructions of small chemical ovens to reflect on the role of experimental heat in the development of theories on the nature of life in the eighteenth century. Working in a similar vein but with culinary recipes, Marissa Nicosia, from Cooking the Archive, examines the problem of heat control in her recipe recreation adventures, outlining the challenges of translating cooking instructions meant for the early modern hearth to the modern gas stove.

The four elements, four qualities, four humours, four seasons, and four ages of man. Airbrush by Lois Hague, 1991. Wellcome Collection.

Other authors in the series took our invitation as an opportunity to investigate heat in medical theories across time and place. Aileen Das kicks off this series by arguing that heat occupied a central place in ancient Greek, Roman and medieval Islamicate theories about the human body and its care. Taking on the smelly problem of perspiration and body odor, Cari Casteel reminds us that this issue is as old as mankind and offers several remedies from Roman authors.  Catherine Rider, on the other hand, examines notions of heat in fertility remedies in medieval England, noting that, whilst popular, heat-based treatments (to either increase or reduce heat in the body) were not the only kind of fertility aid available to English couples. The series concludes with two posts focused on fever and disease. Writing on in Late Imperial China, Marta Hanson introduces us to ideas of fever in Chinese medicine. Finally, Nukhet Varlik turns our attention to the ambiguities inherent in early modern taxonomies of infection diseases, exploring fever as a symptom and as a disease category.

We’ve had a great time editing this series – hope you enjoy reading the posts wherever you are. Happy summer and stay cool!

Marieke Hendriksen and Elaine Leong

P.s. We were so inspired by our contributors’ posts that we’ve decided to dedicate the December issue to (you guessed it) COLD!. If you’re interested in joining the conversation, send a short pitch to recipes@mpiwg-berlin.mpg.de.