A BRIEF HISTORY AND REVIEW OF THE EARLY PRACTICE AND MATERIALS OF GAP-FILLING IN THE WEST
The main object of this article is to introduce the reader to the history and variety of materials that may be present as fills for voids in three-dimensional objects and to briefly explore the philosophy and social context of repairing and filling objects over the last few centuries. This is not a comprehensive search of the recent conservation literature dealing with filling and compensation, but useful references have been provided for most of the topics and materials discussed so that the reader can explore them more fully.
The second half of the article is a representative catalog of materials that have been used for fills. Some of these are traditional in the sense that they have a long history of use, while many others were the result of an explosion of materials and innovation that began at end of the 18th century. Fills and filling materials that fall within the currently accepted practice of the modern, trained conservator are discussed in more detail in other contributions to this issue of JAIC. More space is given here to materials that are not extensively discussed elsewhere.
The documentary sources for traditional restoration practices are sparse (a state of affairs elaborated on more fully by Marijnissen 1996). Adhesives and cements are described in the earliest European treatises such as the Leiden and Strasbourg manuscripts (parts of which date to classical antiquity) and the treatise of Theophilus, generally dated to the early 11th century, but there are no specifics for restoration procedures per se. The first published information on restoration dates to the 18th century, usually as part of longer works, and the first treatises devoted to art restoration (usually paintings), such as that of Giovanni Secco Suardo, appeared in the mid-19th century (Marijnissen 1996). Several compendia of American newspaper advertisements of the 18th and early 19th centuries provide notices of the repair activities of craftsmen and list a few menders and restorers (Dow 1927; Gottesman 1938, 1954, 1965; Prime  1968); these can probably be interpreted as indicating the state of the art during that era. Books of formulas and household hints became very popular during the 19th century (for example, Campbell 1867; Youman 1876; Moore 1882; Brannt 1886), many of which contain recipes for adhesives and filling materials, but these were often uncritical compilations taken from earlier works in a tradition that in some instances stretched back into antiquity.
Much more extensive compendia of workshop methods and recipes usually claiming to be based entirely on practical experience (but also owing a debt to the earlier compendia) became popular during the later 19th century and were reprinted and revised many times. These include the Scientific American Cyclopedia of Receipts Notes and Queries(Hopkins 1906), Spon's Workshop Receipts (1932), and Cassell's Cyclopedia of Mechanics(Hasluck 1904). It was also at this time that various English-language works specifically devoted to restoration of objects first appeared. Authors of practical books on restoration such as those by Barthelet (1884) and Leland (1896), which are extensively cited in this article, took pains to stress that their recipes were tried and true and their instructions based on long experience, although Leland's book relied heavily on recipes from a German-language work on adhesives and cements that he cites as Sigmund Lehner's Die Kitte und Klebemittel.
In our own century there has been a proliferation of restoration and “fix it” books (Ormsbee 1949; Savage 1954; Taubes 1969) directed at restorers, do-it-yourselfers, and antique dealers. This genre continues to be popular and to perpetuate many otherwise outdated techniques. A relatively recent manual on the restoration of ceramics (Parsons and Curl 1963) is devoted to techniques of riveting and filling that would be entirely familiar to a 19th-century restorer.
1.2 HISTORICAL OVERVIEW
Before the advent of professional restorers, objects got fixed, but who fixed them and what considerations guided their practices are largely unknown. Informed conjecture supported by limited documentary evidence suggests that objects were repaired by the user or owner with materials that were familiar and available or were entrusted to a craftsperson who produced similar objects, on the assumption that these specialists were best qualified to understand and repair the products of their crafts. Sometimes objects were turned over to specialist menders and repairers or, increasingly during the 19th century, restorers, who distanced themselves from the humble menders on the basis of greater technical and aesthetic expertise.
1.2.1 MAKERS AS MENDERS
It may seem self-evident that craftspeople had a long tradition of repairing and restoring the objects relevant to their specialties, although a mid-18th-century descriptive compendium of trades and tradesmen (Campbell  1969) does not specify mending as a function. Advertisements do mention this service, however. Cabinetmakers, jewelers, pewterers, and braziers all announce their repair function occasionally, and gunsmiths and clock- and watchmakers often do so (Dow 1927; Gottesman 1938, 1954, 1965; Prime  1968). Repairs and fills were apparently intended to be as strong, permanent, and neat as the available technology would allow, with phrases such as “in the neatest manner” and “after the best manner” often used to describe repair work. Making repairs undetectable would not have been the primary intent in most cases, but in practice, use of the same materials and techniques as used in the original manufacture would often have made them so. Examples of these sorts of fills and repairs are constantly encountered by the conservator (or are so indistinguishable as to go unnoticed). In executing these fills, cabinetmakers first thought of wood, metalworkers of metal, stoneworkers of stone, and so forth. It was not limited thinking or expertise alone that made them tend to stick to their own materials. Instead, the techniques by which the objects were made often naturally suggested how they might be mended. In the craft of metal casting, to give just one example, the filling of voids and the replacement of areas that had failed to cast was an intrinsic part of the craft, as old and as necessary as any other part of the process. Very few instructional books on crafts contain information on composite or dissimilar filling materials. Their absence is perhaps due to a traditional craftsperson's scorn of “fillers,” which would have been resorted to only in cases of poor workmanship and lack of skill in creating close fits.1
1.2.2 SPECIALIST MENDERS
Even in the high arts of painting and sculpture, the origins of the mender-restorer are obscure. It can be taken for granted that valuable art objects were repaired in previous centuries, and several famous sculptors, among them Bernini and Algardi, are known to have occasionally restored objects (Picon 1983), but specialist restorers appear to have first come to prominence in the 18th century. The marble statue restorer and maker of ancient and modern pastiches, Bartolomeo Cavaceppi, for example, became wealthy and socially prominent in the Rome of mid-18th century (Picon 1983). The history of the restoration of minor decorative and functional objects is harder to trace with certainty. Although Campbell ( 1969) describes many minor trade specialties, he fails to mention menders and restorers. By the mid-18th century, however, a few such people begin to advertise their craft. A Boston advertisement of 1755 informs readers that they may have their broken china mended with silver or brass rivets and “Cement that will stand boiling Water” (Dow 1927, 88). Gottesman (1938, 86–87) lists several china restorers working in New York, including a certain “James Walker from London” who advertises his mending of “broken china in the neatest and strongest manner, with rivets and cramps” in 1760 and further states that “where pieces are wanting in broken bowls, [he] supplies the defects.” In 1769, Jacob da Costa lists china, glass, marble, and ladies' fans as objects that he repairs, using a “cement so strong that it may be used either in heat or cold.” As with other craftspeople, such restorers claim they do their work “in the neatest fashion” but stress functionality. A London trade card of the period advertises mending of china “with a peculiar art which has never before been found out in this kingdom so as a riveted piece of china will do as much service as when new” (Heal  1968, 42). Da Costa states that he makes the wares “as strong and as useful as ever” (Gottesman 1938, 86). In 1767, Maria Warwell of South Carolina announces that she mends china “in the neatest and most durable manner” (Prime  1968, 149), and another repairer, Nathanial Lane of New York, states in 1767 that if “his work gives way he will as often mend gratis” (Gottesman 1938, 86).
It appears the aesthetic demands that some of these practitioners placed on their work continued to develop as materials and techniques were refined, and no doubt as the market dictated greater visual perfection. The explosion of the market for luxury objects (see below) may also have driven this shift in at least some segments of the market for repairing. Everyday functional objects had to be mended because their owners needed them and could not necessarily afford to replace them. These objects needed to be fixed only well enough to be used. Luxury objects, on the other hand, needed to be fixed well enough to be displayed. Thus one late-19th-century restorer (Barthelet 1884, 10–11) felt it necessary to distinguish his work and himself from the traditional “mender” in the following words: “The china mender differs from the [restorer] for the reason that his assistance is especially required for articles destined for constant use…. Strength and durability united with cheapness of workmanship and promptness of execution are sought to the exclusion of any other consideration…. The joining by means of clasps and rivets is his specialty and very seldom does he pay attention to the looks of his work.”
A few other factors may be relevant to the development of specialist restorers during the 18th and 19th centuries. The nature of production methods promoted an increasing divergence between the making and the mending of many categories of material. During the 18th century and continuing throughout the 19th century, the quantity of possessions owned by most individuals increased enormously, and more and more people were able to afford purely decorative objects. This explosion of manufactured material has been described as the Consumer Revolution by historians (McKendrick et al. 1982; Brewer and Porter 1993). These objects differed from earlier ones (both plain and fancy) in two critical ways. First, many, such as Wedgwood ceramics, were made in factories, often by numerous specialized workers. Second, individuals were increasingly purchasing objects from retail shops and not from the people who made them. These changes had implications for the repair of objects. Before the 18th century the craftsperson who originally made the object was the most logical choice when it came to putting it back into service after damage. In contrast the restoration of factory-made decorative objects would have more commonly involved materials and techniques that were outside the knowledge of the original makers, but these were the stock-in-trade of restorers. Leland (1896, xxi) specifically recommends against entrusting broken objects to the manufacturer, since they “work by machinery or by vast subdivision of labour, and not so to speak by hand. But repairing must be by hand.” Owners were increasingly unable to return objects to their original makers for repairs, thus fostering a growing breed of specialist restorers who worked in small shops far removed from the increasingly industrial setting in which many of the objects they were called on to repair were produced.
In some cases, the nature of the material itself further governed how and by whom it was repaired. Ceramics and glass in particular were the products of pyrotechnologies that for various technical reasons were ill-suited for making repairs. Although ceramics could be and sometimes were repaired by refiring (Williams 1988), this process was uncommon and had never been an option for glass. With these materials in particular, the knowledge of making and repair had always been largely separate. Manufactured ceramics and glass were an important part of the Consumer Revolution, and the sheer quantity of such material, as well as the regard that owners had for these talismans of gentility, may have dictated the apparent emphasis, as expressed in their advertisements, on the restoration of these materials by early mender-restorers.
A further, if minor, note of historical interest relates to itinerant menders. Many rural communities could not support established shops of menders and restorers because of the limited local demand for their services, and itinerants, variously known as tinkers, travelers, and gypsies, added mending of household wares to their repertoire of survival strategies.2 In the British Isles, this work was done by traveling tinkers until relatively recently (Hartley 1939). The simple tools and materials of these craftspeople—the bow drill, wire for rivets, shellac sticks and white lead putty, solder, tin, and fluxes—made it practical for itinerants to service some of the simple repair needs of city dwellers as well. Barthelet (1884, 44) describes the china mender of Paris “with a square box strapped on his back, brightly painted and ornamented…he walks about the street, enters each house yard and causes the air to resound with his guttural and most compound yell, and one must be thankful if he does not accompany it with the more piercing noise produced by his small metal pipe.”
1.2.3 PROPRIETARY ADHESIVES AND FILLS
Proprietary adhesives and fill materials have been widely available since the 19th century, with some specialty adhesives supplied to the public even earlier. The china mender Marie Warwell of South Carolina advertises in 1767 that she sells her special cement “in jelly pots… it may be had of any color and directions are given how to use and preserve it” (Prime  1968, 149). The ease with which prepared adhesives and filling compounds could be purchased and used without any specialized knowledge makes it likely that they will be commonly found on previously restored objects. Leland (1896, 19) states, “There are endless cements for sale by chemists, all warranted perfect.” A certain amount of technological innovation would have made these proprietary mixtures easier to patent, and in any case they would have appealed to a public that by the late 19th century was favorably disposed to science and novelty. Barthelet (1884, 21–22) describes a filling compound based on sodium or potassium silicate as follows: “A specialty has been made of the mixture, which is found on the market put up in twin bottles; in the one is the silicate, the other contains the powder–baryta or white marble dust.”
As the previous quotations suggest, the production of cheap and effective containers may have influenced the availability of proprietary adhesives and fillers just as they did in the case of art materials and drugs (Tice 1992). The quantity of glass bottles produced rose steadily, with accompanying decline in cost as the introduction of bottle-making machines in the mid-19th century made bottles truly disposable. There were numerous patents for such machines after 1859, and by the end of the century, the Owens machine could produce 2,500 bottles in one hour (Derry and Williams 1960). Other new and effective packaging systems included the collapsible metal tube, invented by John Rand in 1841 (The story of the metal tube 1969), and tinned sheet-iron “cans” or “tins” which were steadily improved throughout the 19th century (Derry and Williams 1960). Such packaging improvements gradually eliminated the need for restorers to make their own preparations. By the early 20th century proprietary adhesives and fillers were so ubiquitous and convenient that one work on restoration from that period relies on them almost exclusively (Scott 1926).