Oyster-Shells, Calcification, and Ceramic Cements in the Eighteenth-Century Home

The term ‘cement’ appears in Dossie’s Handmaid to the Arts, a manual which describes with practices ‘subservient to the arts of design, and yet not absolutely a part of those arts themselves’. It defines them as

The term is used almost exclusively for ceramic bonding materials in other period manuals and recipes. They are materials for 'out of the ordinary' occasions - disruptions of the domestic - the slip and shatter of a favourite cup at tea, or the chipping of a rare dinner service by a servant.



Our contemporary experience of glues and fillers are as homogenous, ready to use materials – milliput, a common epoxy adhesive now used for mending broken china, is sold on the strength of a consistent, reliable texture. 

Upon experimentation however, they reveal themselves to be a highly diverse category. This slide shows samples of over 30 cement recipes experimented with over the course of the visit, together with a table that exposes the variety of ingredients used in a selection of recipes from between 1704 and 1821. Given their own objecthood, they are variously waxy, gelatinous, brittle, stony; they smell of vinegar, honey, pine and garlic. They were easily marked with a finger-nail, or snapped at a touch. 





































Quicklime, or calcium oxide, is a ubiquitous ingredient in these recipes. However, its exact action, consistency and behaviour are opaque. Sometimes the reader is instructed to paint it to a break with a feather; sometimes to grind it into a putty; sometimes to pounce it on with a linen bag. Experimenting with this material during my time with DURARE became central to understanding quicklime's agency within this broad corpus of instructions.



This video shows an experiment with modern food-grade quicklime, obtained from a laboratory supply. A powder fine, bright white particulate, it displayed an amazing vivacity due to its highly basic nature. Working with it required a strict safety protocol, working within a fume hood for personal protection, and for it to be neutralised before disposal.

This vivacity raised inevitable disanalogies between the ingredients available in the period and the highly purified materials used in contemporary laboratories. Several recipes mixed the quicklime with egg albumen, created by over-mixing whites until the lacy protiens float to the top. The alkilinity of the quicklime, which has a pH of around 14 when slaked, instantly curdled the albumen when mixed, as can be seen in the video. This curdled mixture is quite useless for repair, as can be seen in the sample of cracked porcelain to the right.



Although there is always a level of separation between the materials available to the contemporary researcher and those of the period - our tools, manufacturing processes, and even mental states being very much removed - the purified quicklime was clearly too different from that available historically.



This failure prompted a return to the sources, and a rethinking of lime. Several recipes recommend making one’s own, as in this 1808 recipe from The New London Family Cook, which emphasises that the best is that prepared in the home from oyster shells, rather than bought from an apothecary.  This qualifier of ‘best’ naturally raised immediate questions. Best in terms of purity? Adhesive qualities? Whiteness? Strength? Alkalinity? Enactment provided a way into these questions.















Oysters were a ubiquitous eating surface in eighteenth-century London. Analogous to today's cardboard and plastic, they were a ubiquitous, self-packaged food. 



They remained popular with all sections of society. The first of William Hogarth's 1755 series ‘Humours of an Election’, shown here in print, satirises a paunchy Oxfordshire mayor reclining as he presides over a whig party, having gorged to collapsing on oysters - a doctor padding at his head and bleeding him.

The genera of ‘Cries’ prints commonly show oyster-sellers plying their trade in the street from baskets or carts, accompanied by snippets of their cries, which would have been part of the auditory milieu of London’s streets. Playing now is Phil Tanners 1937 recording of one of these calls, incorporated into a ballad. 

The shell of the oyster, likewise, was a prolific source of waste. The Thames foreshore remains almost entirely composed of them in places. One of my mudlarking trips to the foreshore in 2020 instilled the scale of the City’s historic oyster consumption, each one crackling underfoot; in the process of their waste, they had begun to intermingle with other medieval, early modern and eighteenth-century eating surfaces, a constantly tumbling mosaic of earthenware, porcelain and shell.



We might frame the re-use of oysters in contemporary terms as recycling. However a better period term may be ‘oeconomy’, as highlighted by the work of Historian of Technology Simon Werret. Shells, as we might see from the foreshore, were such a common material that they would by no means be scarce, and their reuse not thereby an act of thrift; it, as Werret notes, might be better cast in terms of the diverse moral and religious meanings attached to ‘making the most’ of things in the home.



Now, however, we are faced with the oyster which is no longer a daily foodstuff embedded in well trodden cycles of street-dining, waste and reuse. The shells used in this enactment were sourced from a local fish restaurant, no longer being daily fair. 

Enacting the recipe for oyster burning in the ArtLab meant engaging with further disanalogies between the laboratory working environment and the eighteenth-century home. Burning the shells until 'red hot' in a kitchen hearth was not possible within the scope of this experiment; instead, a bunsen burner, sieve and stand was used.



As the oyster shells burned, they initially splintered and cracked from the remaining moisture inside them, making this a dangerous recipe to perform in a fireplace. This process flung shells around the fume hood, and could only be enacted with a colleague in the lab.



A kitchen hearth would have been the natural location for this activity, and the lifespan of a wood fire provided an intuitive temperature, lifespan, and location for the process. Using a bunsen these factors became difficult to anticipate, and the shells were heated on maximum fifteen and thirty minutes. However, this difficulty highlighted that details such as time and heat were not missing from the Family Cook instructions; rather, they were assumed factors of the domestic environment.







Once calcined, oyster shells took on a pale white parlour, laced with streaks of white. The pounding and scraping of the shells to render them into a powder produced a material which was very different from the modern quicklime. Repeated sifting through a course cloth still produced a light grey, sandy textured powder, in which small flecks of shell remained visible.  



Samples of the various limes – the laboratory lime, a piece removed after 15 minutes in the flame, and the completed shells removed at 30 minutes - were tested for their pH by slaking one gram of each in thirty millilitres of water.

Both samples of the oyster-lime, as might be seen from the transposed results of the pH strips to the right, showed a considerably reduced alkalinity compared to the laboratory sample.



In turn, when experimented with, the oyster-lime did not produce the curdling effect of the laboratory material. With the reduced alkilinity, the mixture set slowly, and the remaining pieces of shell became aggregate to fill any minute losses in the break.



The impurity of the material, thereby, becomes central to understanding the Family Cook's use of 'best' when describing home made lime. Its moderated alkalinity is essential to how the cement handles in practice.















In use, the Family Cook’s quicklime foregrounds a tension between lime-based cements and the conceptual category of ‘adhesive’ through which we now understand them. Comparing a simple lime-based cement to other common period bonding materials, such as pounded garlic or isinglass, lime-cements produce a grey, grainy, and relatively fragile repair, while other materials are closer to the invisible, clear substances we consider glues today.  



In reframing lime-based cements, the parallel uses of lime-burning in the period are revealing. Lime was an essential part of improving soil fertility, painting houses, mixing mortar, and was also used as a depletory cream ingredient. 



Importantly however, quicklime was also an ingredient in ceramic bodies. While the composition of hard-paste porcelain - the durable, heat resistant ceramic imported for centuries from China - had been discovered in Europe by Johann Friedrich Böttger in 1708, it remained a closely guarded secret. In Britain, this secrecy resulted in varied alchemical attempts to produce porcelain. 



Although these recipes were closely guarded, those that survive display a much more fluid understanding of what might compose ceramic bodies, and the boundaries between whole and broken. Aaron Hill gives one early attempt to make porcelain; his 1718 essay On Making China Ware in England gives an esoteric method whereby he instructs potters to ‘employ some poor People to buy up all the old, broken China, which every House can afford him’, which is to be ground up in a common grain mill, mixed with gum water and quicklime:

The resonance between these uses of oyster shells - in the fabrication of porcelain, and in cements for the repair of broken vessels, suggests we apply a different lens. While they do not function as an adhesive as we would understand them, they are more deeply connected to the period understanding of porcelain's composition, and to the broader industrial process of the eighteenth-century ceramic industry.

Lime-cements blur the line between making and mending, broken and whole, and filler and body. While I initially intended to assess the adhesive qualities of cements, their bond to different body types, and their resistance to heat and water, working practically with them in their half-complete, liquid form softens these boundaries.



Through their incongruities and dissonances, lime-based cements present themselves as attempts to fabricate ceramic bodies in the home, as opposed to glues or binders. They appear, rather than half-objects, inseparable from the cultural history of collected objects; as composing them as well as sustaining them.



The broader history of eighteenth-century ceramic repair remains obscured by the commonly held understanding of these interventions and later, non-essential additions. Further research will seek to challenge this understanding, using both reconstructive and archive methods to catalogue and experiment with the plethora of period technologies, including handling, riveting and flux-mending.