Skip to Main Content
677/696

Table 1: Duration of different steps in making a bronze sculpture

Table 1
Table 1
Duration of different steps in making a bronze sculpture
The time required for each step depends on many parameters, including the size of the sculpture, its desired finish quality, the casting process employed, the number of parts requiring assembly, the amount of repair and fettling necessary, the type of patina used, and more. Time also depends on the available technologies and the production environment (e.g., a specific commission in a small workshop versus industrial production of a replica in an industrial foundry). Some extreme examples are given here based on historical documents and direct knowledge of recent fabrications.
PROCESS STEP GENERAL COMMENTS SPECIFIC EXAMPLES APPROX. DURATION DETAILED PROCESS ILLUSTRATIONS
: making the wax Given the variety of methods used to prepare the wax, the varying complexity of models, and the range of sizes that may be encountered in lost-wax casting of bronze sculpture, time to form the wax model may vary greatly (see GI§2.2, GI§2.3). Head of Apollo of Lillebonne (H. 18 cm), Fonderie Coubertin(1) 3–4 hours Making a plaster piece mold of the 3D resin print took 2 hours, including setting of the plaster. Time to prepare the wax model depended on the process chosen: 1 hour was needed for slush molding; 1.5 hours for the indirect wax-slab process; 2 hours for lasagna. figs. 15, 17, 24, 74, 377
Horse head by Andrew Lacey (H. 45 cm)(5) 1 day Making a a two-piece silicone rubber mold of the original clay model took 1 day; making the wax inter-model (slush molding) took 1.5 hours. video 3
Andrew Lacey’s experimental replica of the Satyr and Satyress by Andrea Riccio (H. 18.5 cm) (after original in the V&A: A.8-1949, presented by Art Fund) 3 days A direct process was used; the hand modeling took 3 days. fig. 562
Rodin’s Gates of Hell (H. ~6 m), Fonderie Couberin(2) 1.3 years A total of almost 13,000 person-hours were recorded for molding the model, pouring wax in separate sections (two main sections and 136 small ones), assembly of waxes, insertion of armatures, and core. Considering 5 persons working simultaneously, this meant 64 weeks of work for the foundry. video 17
: applying and completing the refractory mold Once sprueing is carried out (see GI§2.7) and the investment and core are set, the refractory mold is baked to dry it fully and melt out the wax (see GI§2.1.1). Head of Apollo of Lillebonne (H. 18 cm), Fonderie Coubertin(1) 4 hours Sprueing took 30 min.; pouring and setting of the plaster for both core and investment took 30 min.; 3 hours firing in a kiln were necessary to ensure that the plaster core and refractory mold were free of wax and moisture. -
Horse head by Andrew Lacey (H. 45 cm) 5 hours Sprueing took 1 hour; making the ceramic shell investment of seven layers took 2.5 hours spread over 3 days of drying; dewaxing 30 min.; kiln firing 1.5 hours. video 2
Andrew Lacey’s experimental replica of the Satyr and Satyress by Andrea Riccio (H. 18.5 cm) (after original in the V&A: A.8-1949, presented by Art Fund) 4 hours Sprueing took 30 min.; making the investment 2 hours; dewaxing 10 min.; kiln firing 1.5 hours. -
Rodin’s Gates of Hell (H. ~6 m), Fonderie Couberin(2) 3 months A total of ~760 person-hours were recorded for making the ceramic-shell investment. Considering 5 persons working simultaneously, this meant 4 weeks of work for the foundry. 2 months were then needed to dry and bake the investment. video 17
Comparison of two monumental equestrian statues: François Girardon’s monumental Louis XIV (cast by Balthasar Keller in 1699) and Edme Bouchardon’s Louis XV (cast by Pierre Gor in 1758)(3) 1 month Once the wax was withdrawn, it took 23 days to bake the refractory mold and the core for the Louis XIV versus more than 27 days for the Louis XV, including the cooling down. Note that the building of the huge brick refractory molds (whether buried [Louis XVI]; or not [Louis XV]) certainly required several days, although not specified by Boffrand or Mariette. fig. 45
The process here includes the formation of the chef-modèle, ramming the sand around the chef-modèle (including the formation of piece mold sections), formation of the core, and drying of the mold (see GI§2.4.1). Head of Apollo of Lillebonne (H. 18 cm), Fonderie Coubertin(1) 1–2 days Preparing the sand casting mold took <0.5 days; drying the mold took approximately 1.5 days. fig. 62
Two sculptures of two very different sizes by Santiago Calatra Valls, cast by Fonderie Coubertin: Support de table homme assis (H. 70 cm), and Grand disque solaire fendu (D. 300 cm)(6) Small sculpture: 8 days; large one: 1.5 months The formation of the plaster chef-modèle took 5 person-hours for the small sculpture, 35 person-hours for the large one (5/35). Ramming of the sand required 30/210 person-hours; forming of the core 25/175 person-hours. Drying of the sand was accelerated by using carbon dioxide. Considering one person alone for the small piece and two people working simultaneously for the big one, this meant ~8 days total work for the small sculpture and 1.5 months for the larger one. -
melting the metal Time needed to melt the metal can vary greatly and depends on the type of furnace and fuel used, the capacity of the crucible or furnace load, the quantity of metal, and the alloy composition. Head of Apollo of Lillebonne (H. 18 cm), Fonderie Coubertin(1) 1 hour Melting the batch of metal (~50 kg) in an induction furnace took 1 hour. -
Horse head by Andrew Lacey (H. 45 cm) 1.5 hours 1.5 hours needed to melt 45 kg of alloy in a gas furnace and degassed by poling with a hazel stick. -
Andrew Lacey’s experimental replica of the Satyr and Satyress by Andrea Riccio (H. 18.5 cm) (after original in the V&A: A.8-1949, presented by Art Fund) 30 minutes 30 min. needed to melt 3 kg of alloy in a charcoal hearth using Cu90% Sn10%, degassed and cleaned by poling with a hazel stick (for a final sculpture weight of 1.98 kg). -
Rodin’s Gates of Hell (H. ~6 m), Fonderie Couberin(2) 12–20 hours 8.5 tons of metal were needed for the two main pieces.Thanks to several improvements in the reverberatory furnace, the melting time dropped from 20 hours for the first edition in 1981, to 16 hours in 1992, to 12 hours in 1996. 500 kg of metal were needed for the small pieces, melted in a small gas furnace. video 17
Two sculptures of two very different sizes by Santiago Calatra Valls, cast by Fonderie Coubertin: Support de table homme assis (H. 70 cm), and Grand disque solaire fendu (D. 300 cm)(6) Small sculpture: 6 hours; large one: 40 hours 150 kg of metal was melted for the small piece, 1,500 kg for the large one. -
Comparison of two monumental equestrian statues: François Girardon’s monumental Louis XIV (cast by Balthasar Keller in 1699) and Edme Bouchardon’s Louis XV (cast by Pierre Gor in 1758) 1–2 days For the cast of Louis XIV, the furnace was heated for 40 hours, including 24 hours to melt the ~41 tons of metal (84,000 French pounds), versus 28 hours for the 29 tons of metal (60,000 French pounds) for the cast of Louis XV. -
of the metal Pouring of the metal never exceeds several minutes, even for monumental bronzes (see GI§2.7). Head of Apollo of Lillebonne (H. 18 cm), Fonderie Coubertin(1) 10 seconds The pour lasted less than 10 sec. Two people were needed to take the crucible out of the induction furnace and to feed the mold. One more was needed to prevent slags from entering the mold. video 18
Horse head by Andrew Lacey (H. 45 cm) 30 seconds The single-handed pour using an electric hoist lasted 30 sec.: ~10–12 sec. for the two casts with 8–10 sec. between to steady the crucible. The bronze was melted in a gas furnace and degassed by poling with a hazel stick. video 11
Andrew Lacey’s experimental replica of the Satyr and Satyress by Andrea Riccio (H. 18.5 cm) (after original in the V&A: A.8-1949, presented by Art Fund) 6 seconds This very small pour took no more than 6 sec. from a 3 kg crucible held in blacksmith tongs. The bronze was melted on a charcoal hearth using Cu90% Sn10%, degassed and cleaned by poling with a hazel stick. video 9
Rodin’s Gates of Hell (H. ~6 m), Fonderie Couberin(2) 55 seconds To feed the main mold, 7 min. were required to transfer the metal from the reverberatory furnace to the quenouilles (holding) basin. Subsequent feeding of the mold took 55 sec. video 17
Two sculptures of two very different sizes by Santiago Calatra Valls, cast by Fonderie Coubertin: Support de table homme assis (H. 70 cm), and Grand disque solaire fendu (D. 300 cm)(6) Small sculpture: 90 seconds; large one: 150 seconds - -
Comparison of two monumental equestrian statues: François Girardon’s monumental Louis XIV (cast by Balthasar Keller in 1699) and Edme Bouchardon’s Louis XV (cast by Pierre Gor in 1758) a few minutes The duration of the pour is described as “en très peu de temps” (very little time) for the Louis XIV; the pour took 5:04 min. for the Louis XV. -
, , and repairs The amount of fettling, chasing, and repairs undertaken depends on several parameters, including the success of the casting, the type and degree of chasing desired, as well as the number and type of repairs and assemblies undertaken (see I.4, I.5). Nevertheless, these are often the most time-consuming steps in the making of a bronze (see also fig. 3). For more on fettling and chasing see GI§2.9, I.6). Head of Apollo of Lillebonne (H. 18 cm), Fonderie Coubertin(1) 6 hours Fettling took 2 hours, chasing 4 hours. The hole in the face was relatively quickly repaired with a welding rod. figs. 73, 121
Horse head by Andrew Lacey (H. 45 cm) 6 hours Fettling took 2 hours, chasing and repairs 4 hours. video 11
Andrew Lacey’s experimental replica of the Satyr and Satyress by Andrea Riccio (H. 18.5 cm) (after original in the V&A: A.8-1949, presented by Art Fund) 2 hours Fettling took 15 min., chasing and repairs 2 hours. -
Andrew Lacey’s reconstruction of a figure (the old man) from one of a pair of sculptures formerly in the Rothschild Collection(4) 1–2 days A more careful application of the first layers of the investment considerably reduced surface imperfections on the second replica, thus requiring half the time for chasing: 1 day instead of 2 days on the first replica. video 13; figs. 4, 5, 105
Rodin’s Gates of Hell (H. ~6 m), Fonderie Couberin(2) 1.4 years A total of ~13,600 person-hours were recorded for fettling and chasing. Considering 5 people working simultaneously, this required 68 weeks. Note that 2 weeks were necessary for the bronze to cool down before fettling could start. video 17
Two sculptures of two very different sizes by Santiago Calatra Valls, cast by Fonderie Coubertin: Support de table homme assis (H. 70 cm), and Grand disque solaire fendu (D. 300 cm)(6) Small sculpture: 1 week; large one: 3 weeks 5 person-hours were needed for the fettling of the small piece, versus 30 person-hours for the large one. Chasing lasted 32 versus 225 person-hours. Considering one person alone for the small piece and two working simultaneously for the big one, this meant ~1 week (respectively 3 weeks) of work for the foundry. -
Comparison of two monumental equestrian statues: François Girardon’s monumental Louis XIV (cast by Balthasar Keller in 1699) and Edme Bouchardon’s Louis XV (cast by Pierre Gor in 1758) A few years Due to major casting flaws, chasing and repairing the monumental cast of Louis XV took 5 years. No indications are given by Boffrand on the time needed to finish the cast of Louis XIV. -
For more on patination, see I.8. Other finishing processes such as metal plating and inlaying might be carried out instead of or in addition to patination. Head of Apollo of Lillebonne (H. 18 cm), Fonderie Coubertin(1) 1 hour Chemical patination took 1 hour. -
Horse head by Andrew Lacey (H. 45 cm) 1 hour Chemical patination took 1 hour. video 16
Andrew Lacey’s experimental replica of the Satyr and Satyress by Andrea Riccio (H. 18.5 cm) (after original in the V&A: A.8-1949, presented by Art Fund) 1 hour Chemical patination took 1 hour. -
Rodin’s Gates of Hell (H. ~6 m), Fonderie Couberin(2) 4 weeks 1,560 person-hours were recorded for the chemical patination, representing 4 weeks of work. video 17
Two sculptures of two very different sizes by Santiago Calatra Valls, cast by Fonderie Coubertin: Support de table homme assis (H. 70 cm), and Grand disque solaire fendu (D. 300 cm)(6) Small sculpture: 2 days; large one: 2 weeks Chemical patination took 2 days/2 weeks. video 17
1
Although the casting of reproductions of the Apollo heads illustrated here was carried out by inexperienced attendees of a training workshop in 2016, all of the reported durations have been adjusted for skilled craftspeople based on interviews with professional foundry workers.
2
Three editions of the monumental Gates of Hell have been cast by the Fonderie Coubertin: 1981, 1992, and 1996. Details of the casting processes in use at the Fonderie Coubertin can be found in ; .
3
More details in , 54, 57; ,111; .
4
More details in . See also in the present publication II.9§2.2.
5
See Case Study 7 for a detailed description of the process.
6
The plaster models provided by the artist were enlarged at the foundry.