While working on the Ars Vitraria Experimentalis (1678), the principle book on seventeenth-century glass, I came a across a peculiar remark. The author of the book, the German alchemist and glassmaker Johann Kunckel (1630-1703) composed a commentary on a series of Italian glaze recipes, and somewhere along he dropped the following line: “reproducing this glaze requires as much Art as inventing it” (p. 193). I was struck by this remark and have been thinking about it ever since. What is it that Kunckel tried to tell us here? What does it tell us about recipes, these miraculously concise pieces of text? And how do these written instructions fit into workshop practices? After all, when reproducing a recipe becomes an investment that equals its invention from scratch – why bother with books at all?
That people bothered is in fact beyond dispute. Recipe research from the past years has come up with ample reasons why people engaged with practical texts. People were working on their reputation, tried to organize experiential knowledge, or were concerned about the epistemic status of their crafts. And indeed, all these elements instantly return in Kunckel’s Ars Vitraria Experimentalis. Kunckel is particularly keen on stressing that everything in his book has been vetted through experience. His book reads as an attempt to apply for a good position at the Brandenburg court, and he openly runs down his main competitor, Friedrich Geißler, who worked on a similar book project. “Lieber Herr Geißler, I am sorry that you are so utterly unfortunate in your judgments and comments” (p. 188). In the end, however, we should not forget that the Ars Vitraria Experimentalis was born out of practice. It finds its basis in the workshop, amidst the radiant heat of furnaces, brightly glowing glass, skilled labor and the stinging smell of smoke.
We dragged wood, stoked furnaces and patiently waited for the heat to come. We tried to control the smoke and played games guessing temperatures from different shades of bright orange. Showers at the end of the day invariably turned my white bathtub into a deep brown. During these days, our main occupation was fire. Ingredients for the glaze, their quantities and the order in which they had to be combined became mere side issues.
It was in this smoky atmosphere that we began to see a fundamental characteristic of Kunckel’s commentary. The focus of commentaries, annotations and marginalia in practical texts had traditionally been the testing, correcting and improving of recipes, but Kunckel took a slightly different approach. He started to dress up Neri’s recipes in his commentary and added new and previously unarticulated layers to the original recipes. What layers? Well, think for instance about the role of fire. While Neri straightforwardly communicated ingredients, ratios and the different steps in his glaze recipes, nothing prepared us for the important task that fire management turned out to be, which went far beyond sending some wood up in flames. Kunckel, on the contrary, emphasizes this very issue in his commentary, and repeatedly argues that “the Fire is the principle thing to observe” (p. 194).
Indeed, while working with different furnaces, we learned that furnaces are more than simple and inert providers of heat. Instead, wood-fired furnaces become a tool by which the quality of the glass is shaped in addition to the ingredients and the quantities prescribed by the recipe. Temperature, atmosphere and position in the furnace are all partly responsible for the end result. In the end, reworking the same recipe in three different furnaces left us with three sets of glazes in different qualities. See how Kunckel cleverly shifted the perspective in Neri’s recipes? Kunckel made his readers aware of the circumstances they had to navigate when putting a recipe into practice, something for which Neri left them unprepared.
Making processes can be understood as processes of growth, the anthropologist Tim Ingold tells us. And this stance on making has significant consequences for how we understand the position of texts in these processes. Makers stand in an ecological relation with their environment, their materials, tools, and the forces they work with. To make a glaze means that the molten glass, the furnace, the smoke, etc. act in correspondence with an observant and anticipating glassmaker. Crucially important here is that ideas, designs or written instructions cannot simply be imposed onto reality. Recipes need to become part of it instead. To make something means to adapt and respond to the local and unique joining and intertwining of forces, materials and elements – and written instructions form just one strand in this creative process. Seen in this light, Kunckel’s remark was not so much a pessimistic note on the possibly superfluous nature of glaze recipes, but rather a reminder that reading and reproducing a recipe is an all-encompassing effort to make the recipe work in the unique constellation of the individual workshop. Reproducing a recipe is reinventing the wheel.
Thijs Hagendijk is a lecturer at Utrecht University. Earlier this year, he defended his dissertation on reading and writing practices in the early modern arts, with a specific focus on text usage in historical glassmaking, painting and metalworking. He works on the intersection of technical art history and the history of chemistry, and is interested in performative methods, such as reworking, re-enacting and reproducing historical techniques, materials and processes.
*You can read more about this project in Thijs’ recent article in Ambix.
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.
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.” It was within the confines of this manuscript that I began to discern two themes with respect to cold in practices of making.
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.”  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.”  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.”  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.
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.”  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”.
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.
 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.”  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”.  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.  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.  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.  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”.
This month, we’re excited to collaborate with History of Knowledge to celebrate the upcoming conference, Learning by the Book: Manuals and Handbooks in the History of Knowledge. The five-day event takes place at Princeton in June and features a “blogged conference” to complement traditional panel presentations. For the next few Thursdays, the RecipesProject will cross-post selections from the conference (with RP readers noting the extended length, in keeping with HoK posts). These features are just a taste of more than thirty works produced for the conference, and readers are invited to read the full selection here. Enjoy!
In 1721, the Dutch craftsman Willem van Laer (1674-1722) published a Guidebook for Upcoming Gold- and Silversmiths. Intended as a manual to educate young novices, the Guidebook discussed a variety of different practices, techniques, and skills that ranged from assays to determine the quality of precious metals to sand mold casting and polishing (Figure 1). Four different editions, including one pirated copy, appeared in less than fifty years, attesting to its popularity. The book was explicitly aimed at teaching young readers how to do and make things. Van Laer reassured readers by saying “there will be few young gold- or silversmiths, who won’t find anything to their liking and benefit while reading this book; they will be led by hand to the knowledge of many things.” Yet, however confident Van Laer might come across in this passage, there is sufficient reason to question the actual success of Guidebook at explaining and delivering these skills. Practical knowledge is often better demonstrated than written down. Van Laer was very well aware of this fact and offered disclaimers warning his readers that full comprehension of the text was only achieved when complemented with manual instruction. This begs the question of what could, in fact, be learned from the Guidebook.
The best way to answer this question is to look at historical evidence, primarily in the form of marginalia or other signs of usage, that indicates how the Guidebook was read and used on the shop floor. Unfortunately, not much of this evidence has survived for reasons that historians Natasha Glaisyer and Sara Pennell have observed in their study of early modern didactic literature. They note an irony in the fact that books that were most read and used did not make it to our libraries. Indeed, most Guidebooks that reside in Dutch libraries are neat and almost spotless copies – we even found a copy with its pages still uncut! (We ended up cutting its pages almost three hundred years after publication, but that is another story). This virtual lack of historical evidence pushed us in a different direction. We decided to approach the Guidebook experimentally by performing historical re-enactments. By reading and working with the text as if we were learning how to make and do things, we were able to get a better grasp of Van Laer’s potential audience and the role the book might have played in historical learning practices and the acquisition of practical skills. The re-enactments gave rise to various insights. In this post, we discuss one specific result, which is a story involving both success and failure.
Part of Van Laer’s discussion of soldering features the introduction of a “convenient soldering lamp.” Even though the better part of soldering usually happened in the forge, Van Laer presents his soldering lamp so that “the maker won’t need to put the entire piece back into the fire for a tiny leak or mistake only.” For a silversmith, putting a soldered piece back into the fire was always risky as the soldered joints could melt again and cause more trouble than initially was the case. The preferable method was to repair a soldered piece without having to expose it again to relatively high temperatures, which is where the soldering lamp comes in. Basically, the soldering lamp resembles a modified oil lamp with an extended snout. To reach temperatures high enough to melt the solder, one had to use a small blowpipe to blow additional air through the flame. Skillful blowing would subsequently result in a second tiny yet feisty blue flame hot enough to locally melt silver. That is, at least, what Van Laer seemed to suggest: “when the tip of the flame of such burning Lamp is blown against the spot that needs to be soldered, it makes it hotter over there and the solder will easily run.”
To find out whether we could indeed solder this way, we decided to build a soldering lamp following Van Laer’s instructions. Luckily, Van Laer was meticulously detailed with respect to the lamp, discussing its dimensions and the materials needed to produce it. According to him, the lamp should be made from brass and should measure 3 inches across and 1 inch in height. Additionally, there should be a wooden handle at its back and at the front a snout of about 5 or 6 inches long. To make sure he was well understood, Van Laer also included a schematic engraving of the lamp (Figure 2). We had more than enough information to work with, and based on his drawings and instructions we produced a much-desired replica of the lamp (Figure 3). We also laid our hands on a few historical blowpipes. Now that we had the materials, we could learn to handle the tool.
We filled the lamp’s reservoir with olive oil and stuffed its snout with a cotton lump. When we finally lit the lamp, the burning oil filled the room with a scent of grilled food. As an initial exercise, we took a small brass strip and tried to heat it until it started to glow. Here is how it went down, as recorded by Thijs in our fieldnotes:
Glowing the metal strip did not happen before we learned our first big lesson. Intuitively, Tonny and I started out by blowing hard through the blowpipe. The more air, the hotter the flame we thought. After trying for quite some time, it seemed as if we weren’t making any progress. We could steer the yellow flame, but were not able to get the blue flame where we wanted it. Yet, after I tried some more, it suddenly appeared that I had been blowing way too hard. By blowing rather softly on to the flame, suddenly the little blue flame emerged. In general, the blowing required much exercise. When later that afternoon a visitor dropped by for an interview, we saw the amount of skill that we already acquired. She too tried to produce a feisty blue flame by blowing through the flame, but did not succeed. To my own surprise, I was immediately able to point out what went wrong. The tip of the blowpipe should almost touch the pit of the flame, while one should blow out of the flame, both from beneath and from the inside-out. Cheeks filled with air, meanwhile breathing in, breathing out, breathing in, breathing out, filling the cheeks again and keep blowing at the same time. A rhythm occurs in blowing and breathing, which maybe most resembles what happens to your breathing when running.(Fieldnotes Thijs, April 4th, 2017).
Until this point, then, the story was quite successful. We were able to reverse-engineer the soldering lamp, and, like Van Laer explained, we could reproduce the feisty blue flame. Moreover, the blue flame proved rather hot indeed, as indicated by the different oxidation colors on the brass strip. However, as soon as we tried taking it to the next level, we ran into trouble.
Still happy with the progress we made, we now wanted to solder a very basic joint. We took another brass strip, hammered it round, and set out to solder its ends together to make a tiny cylinder. We fixed the cylinder in a standing pair of tweezers to free both our hands so we could steer the soldering lamp and hold the blowpipe. A little piece of solder was put on top of the joint, as well as little bit of borax, which is a flux used to facilitate the flow of melted solder. We lit the lamp and started blowing (Figure 4).
One hour later we were so out of breath that we stopped, but the cylinder had not yet been soldered. We failed. Even though we raised the temperature high enough to make the solder curl up like a drop, we never reached the final state in which it flows out and runs into the joint. Using the soldering lamp appeared less straightforward than we thought it would be.
We were curious to know what went wrong, but after several more days of trial-and-error, the list of questions and issues had only grown. We turned to the Guidebook and read and re-read the passages, only to discover that Van Laer was actually quite silent on the matter. Indeed, he carefully described how to assemble the soldering lamp, but spent hardly any time on how to handle it in practice. Should the object be pre-heated, or could the soldering lamp be used on cold objects, too? We blew and soldered against a piece of charcoal to create a reverberating heat source, but was this also how Van Laer meant to use the soldering lamp? Moreover, what type of solder should we use? Van Laer listed three distinct recipes for solder with different melting points, but did not indicate which one to use in combination with the soldering lamp. To date, we still have not been able to solder a proper joint using the lamp.
Interestingly, if we compare the above experiences with other re-enactments we performed, a general pattern starts to emerge. For example, with respect to sand mold casting, Van Laer vividly described how to prepare and process the sand, but left his readers hanging when it came time to assemble a mold from it. Moreover, in his discussion of chasing, he meticulously described how to transfer a design to silver, but gave no guidance on how to perform the actual chasing process. Why would Van Laer alternate between exacting detail and virtual silence? What does this say about the usability of the book? And what could, in fact, be learned from this text?
The soldering story followed a similar pattern. While Van Laer carefully discussed each and every condition needed to succeed – the soldering lamp, recipes to prepare multiple types of solder, different sorts of fluxes – we failed once we arrived at the procedure itself. Is this due to our lack of skill in operating the blowpipe and soldering lamp, or are there aspects of eighteenth-century soldering that we no longer understand? In any case, the Guidebook’s guiding principle seems to be that core operations are best demonstrated rather than put into words. Van Laer did in fact confirm this with respect to the casting procedure. Just as he came to the very heart of the procedure, he abandoned his detailed exposition, stating that “the molding and casting cannot be learned as well as through manual education.”
During our re-enactments, we therefore came to interpret the Guidebook as a text containing advanced practical knowledge, including tips, tricks, and best practices. Learning new skills from scratch, such as soldering, casting, or chasing, is still best done through manual education, but once mastered, the Guidebook can indicate new routes, spell out different paths, and show new variations on a theme.
 Willem van Laer, Weg-wyzer Voor Aankoomende Goud en Zilversmeden: Verhandelende veele wetenschappen, die Konsten raakende, zeer nut voor alle Jonge Goud en Zilversmeeden (Amsterdam: Fredrik Helm, 1721).
 Natasha Glaisyer and Sara Pennell, “Introduction,” in Didactic Literature in England 1500-1800, edited by Natasha Glaisyer, Sara Pennell (London: Ashgate, 2003), 7.
 For a more elaborate and contextualized overview of the re-enactments performed on the Guidebook, see Thijs Hagendijk, “Learning a Craft from Books. Historical Re-enactment of Functional Reading in Gold- and Silversmithing,” Nuncius 33, no. 2 (forthcoming Summer 2018).