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Miklós Boskovits (1935–2011), “Agnolo Gaddi/Saint Bernard and Saint Catherine of Alexandria with the Virgin of the Annunciation [right panel]/shortly before 1387,” Italian Thirteenth and Fourteenth Century Paintings, NGA Online Editions, (accessed October 28, 2016).


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Mar 21, 2016 Version

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Most early paintings are also mystery stories, making the art historians who study them detectives of a sort. Signatures were not routine, and the inscriptions on this large altarpiece name the saints depicted, not the artist who painted them. In this case, however, the elegant figures, pastel colors, and decorative effects have pointed experts almost unanimously to Agnolo Gaddi (Florentine, c. 1350 - 1396), Florence’s most sought-after artist during the late 1300s. The more difficult question is who commissioned it, and for what place? Although hypothetical, one answer seems likely: that it was given by the prominent Florentine family of Benedetto di Nerozzo Alberti for the church of San Miniato, which stands atop one of the city’s highest hills.

We know that Alberti commissioned Gaddi for other works, and that in 1387 he added a codicil to his will providing funds for decorations in San Miniato. It is the inclusion of the particular saints we see here that links the National Gallery of Art’s altarpiece to the Alberti family and perhaps to that document. At left is the apostle Andrew, holding the symbol of his crucifixion and the rope that was used in place of nails to hang him on the cross. He was the patron saint of Alberti’s deceased son. Next to him, Benedict, considered the founder of western monasticism, displays the opening words of the rule that governed the Benedictine monks at San Miniato. Benedict was also Benedetto’s patron saint. Opposite stands Bernard of Clairvaux, the powerful French abbot of the Cistercian order. He was the patron of another of Benedetto’s sons. Finally, we find Catherine of Alexandria on the spiked wheel of her torture. Both Benedetto and his son Bernardo made dedications in her honor, and some medieval etymologies linked her name to catena, Latin for chain, a device that figured on the Alberti coat of arms.


This panel is part of a triptych that consists of two laterals with paired saints (this panel and Saint Andrew and Saint Benedict with the Archangel Gabriel [left panel]) and a central panel with the Madonna and Child (Madonna and Child Enthroned with Twelve Angels, and with the Blessing Christ [middle panel]). All three panels are topped with similar triangular gables with a painted medallion in the center. The reduction of a five-part Altarpiece into a simplified format with the external profile of a triptych may have been suggested to Florentine masters as a consequence of trends that appeared towards the end of the fourteenth century: a greater simplification in composition and a revival of elements of painting from the first half of the Trecento.[1] Agnolo Gaddi followed this trend in several of his works. He demonstrates this in the three panels being discussed here by his deliberate revival of motifs that had been abandoned by most Florentine painters since the mid-fourteenth century. To present the Madonna seated on a throne of Giottesque type,[2] instead of concealing the structure of the throne with a gold-embroidered cloth of honor as in most paintings realized by masters in the circle of Orcagna, was a sort of archaism at this time. Agnolo scrupulously describes this seat and at the same time exploits its form to create three-dimensional effects. Yet these archaizing motifs are combined with more forward-looking features. Gaddi’s progressive adjustment to the innovative late-­Gothic taste of his time is thus attested by various aspects of the triptych, such as the pastiglia decoration in the gables, the now lost decoration of the frame,[3] the rich orientalizing carpet that covers the floor,[4] and even the crowded composition of the central panel.

Lionello Venturi published this triptych in 1931 under the name of Gherardo Starnina.[5] This attribution was based on the now discarded theory of scholars who had tried in the first three decades of the century to reconstruct the oeuvre of a putative disciple of Agnolo Gaddi, to whom the conventional name “Madonnenmeister” or “Compagno d’ Agnolo” was given and who was later identified with Gherardo Starnina.[6] However, Bernard Berenson recognized that a good part of the work given to the “Compagno d’Agnolo” belongs to Agnolo himself. The studies of Ugo Procacci [7] on Starnina finally put the proposed identification to rest, though it continued to enjoy residual credit for some time to come.[8] In the National Gallery of Art, the altarpiece was cataloged as a work by Agnolo Gaddi, and since the 1960s, art historians have unanimously accepted this attribution. 

The present writer proposed that Agnolo Gaddi’s altarpiece might have been executed for the sacristy of the church of San Miniato al Monte (Florence),[9] of which the Alberti were patrons and for whose decoration Benedetto di Nerozzo Alberti left funds in his will of 1387.[10] The reasons adduced at that time in support of such a hypothesis were, it must be admitted, not quite convincing: referring to the inscription in Saint Benedict’s book to the “admonition” (an administrative sanction by the Florentine government) against Alberti in 1387 and his subsequent exile is open to question. Furthermore, I erroneously asserted that Saint Giovanni Gualberto was represented in the painting. The saint to the right of the Virgin is, in fact, Bernard of Clairvaux, but the presence of this saint in the altarpiece is actually a further argument in support of a provenance from the sacristy of San Miniato. Saint Bernard was the patron Saint of Benedetto Alberti’s son Bernardo, who in his will dated 1389 left money for masses to be celebrated annually pro anima dicti testatoris (for the soul of the said testator) in the family chapel in San Miniato, which had evidently already by that date been consecrated.[11] The representation of Saint Andrew, who was the patron saint of a predeceased son of Benedetto Alberti, also links the altarpiece to the sacristy of San Miniato. As to the fourth saint, Catherine of Alexandria (standing on a broken wheel), she was evidently much venerated in Benedetto’s family. This is proved by the fact that, in his will of 1387, he bequeathed money for the decoration of an oratory near Florence (Santa Caterina dell’Antella) dedicated to the martyr saint of Alexandria (and decorated by a cycle of frescoes illustrating scenes from her life by Spinello Aretino); additionally, his son Bernardo wished to build a monastery and a church in her honor.[12] The Alberti family’s veneration of Saint Catherine may have been based on the popular etymology of her name (catherine = catenula) diffused by Jacopo da Varazze in Legenda aurea,[13] with reference to the chain represented in the Alberti coats of arms.

Although the provenance from San Miniato remains a hypothesis, it still seems to me a quite plausible one that, if correct, would give us the certainty that by 1830 the triptych was still on the altar of the sacristy. An altarpiece can apparently be seen still in situ in a sketch of the sacristy’s altar wall [fig. 1] made in that year by architect Christoph Robert August Roller (1805–1858), in his Tagebuch einer italienischen Reise (Castle Museum Burgdorf, Burgdorf, Switzerland). Unfortunately, the sketch, to which Stefan Weppelmann kindly drew my attention, is very small and certainly not sufficient for the identification of the triptych in the Gallery. What may be said for certain is only that an altarpiece composed of five panels stood on the altar of the sacristy of San Miniato in 1830, but by 1836 this altarpiece was no longer there, as Stefan Weppelmann rightly observed. It was removed and sold presumably by the Pia Opera degli Esercizi Spirituali, which had owned the furniture and decorations of the church since 1820.[14]

As for its date, the Gallery’s first catalog (1941) cautiously suggested “the last quarter of the XIVth century,” while the volume devoted to the Duveen Pictures (1941) proposed an approximate date of c. 1380.[15] More recent publications in general support a time frame within the 1380s, although without explaining the reasons for this proposal. Arguing for a provenance from the sacristy of the Florentine church of San Miniato al Monte, Miklós Boskovits (1975) attempted a more precise dating shortly after the codicil dated 1387 was appended to the testament of Benedetto di Nerozzo degli Alberti, its putative patron.[16] For his part, Bruce Cole (1979) stylistically linked the Gallery triptych with the cycle of frescoes in the choir of Santa Croce in Florence, for which he proposed a date of execution in the years c. 1388–1393.[17] Given the lack of securely datable panels by Gaddi, with the exception of the composite altarpiece of the Cappella del Crocifisso, still in the church of San Miniato,[18] various scholars have attempted to construct a chronology for the artist based on an analysis of the punched decoration of his work; however, this effort has failed to yield any precise indication for the Washington altarpiece other than a vague association with a relatively late phase in the painter’s activity.[19]

In the course of his career, especially between the 1380s and the early 1390s, Agnolo Gaddi produced a number of polyptychs, now in part dismantled and dispersed, of which at least the surviving central panels propose a composition close to that of the triptych discussed here. I refer in particular to Madonna and Child with Eight Angels (now united with laterals that did not originally belong to it) in the Contini-­Bonacossi bequest to the Uffizi, Florence;[20] Madonna and Child Surrounded by Eight Angels in the church of San Lorenzo at Borgo San Lorenzo;[21] the triptych in the Staatliche Museen of Berlin, in which six angels are placed around the throne and a further pair are in the gable;[22] and Madonna and Child Flanked by Twelve Angels, now in a private collection in Milan.[23] None of these is securely dated, but the Berlin triptych can in all probability be identified with that formerly on the altar of the Nobili chapel in Santa Maria degli Angeli, which bore the inscription “An D 1387 Bernardus Cini de Nobilibus fecit fieri hanc cappellam.”[24] This gives us a useful point of reference not only for defining a chronological sequence of the paintings in question but also, as we shall see, for the dating of Gaddi’s great cycles of Florentine frescoes. Another chronological point of reference, albeit an approximate one, is 1383, the date of the testament of Michele di Vanni Castellani, in which he made bequests for the construction and decoration of a family chapel in Santa Croce, the chapel that would later be frescoed by Agnolo Gaddi.[25] The style of this decoration suggests a period of execution not much later than the will; indeed, most art historians tend to place the execution of the cycle in the years immediately following 1383.

Although successive restorations have now made it difficult to assess, the Borgo San Lorenzo panel [26] seems the earliest of the group. It was perhaps painted even before the frescoes in the Castellani chapel, with which it has affinities in its use of dense shadows in modeling, in the rigid profiles of the angels, and in the deeply channeled and brittle-looking folds of their garments. Between that work and the Nobili triptych now in Berlin can be placed both the Madonna of the Contini-­Bonacossi bequest (it too now altered by retouches) and the triptych in the Gallery. In contrast to these latter two, the animated composition of the panel destined for the Nobili chapel seems to represent a further step forward, in the direction of the more dynamic compositions and the more delicate modeling that characterize the painter’s final phase, to which the above-mentioned Madonna surrounded by twelve angels now in a private collection can, I believe, be ascribed.[27]

If such a chronological sequence of the altarpieces executed by Agnolo in the 1380s is plausible, the Gallery triptych ought to date to a period slightly preceding 1387—that is, slightly preceding the execution of the other and more important enterprise promoted by Benedetto di Nerozzo Alberti, the frescoing of the choir in Santa Croce.[28] Various similarities can be identified between passages of that cycle and the Washington triptych, in confirmation of the chronological proximity of the two works: the bust of Saint Andrew [fig. 2] recurs, in similar form, in the scene of the Making of the Cross [fig. 3], in the group of spectators to the extreme right of the fresco, while analogies can also be identified between the other saints of the triptych and the busts of the prophets inserted in the ornamental friezes that articulate the chapel’s decoration. Close similarities have also been observed between the lateral saints of the Gallery triptych and the fragments of an altarpiece now in Indianapolis.[29] We have no secure evidence to help us date these fragments, probably the remains of the decoration of the lateral pilasters of a polyptych roughly contemporary with, or perhaps slightly later than, the triptych being discussed here. In conclusion, therefore, the Washington altarpiece exemplifies a stage in the artist’s career in which he embarked on the gradual discovery of the innovative features of late-­Gothic art. This led him to develop greater elegance in poses, more delicate and harmonious arrangement of draperies, and more spontaneous vitality in the conduct of the angels thronged around the sides of the throne as if drawn magnetically to the child. A clear sign of the innovations of the phase in which Agnolo painted the frescoes in the choir of Santa Croce is also the artist’s polychromy: abandoning the somber palette of previous works, he now prefers or utilizes combinations of delicate pastel colors.

Miklós Boskovits (1935–2011)

March 21, 2016


across the bottom under the saints: S. BERNARDUS DOCTOR; S. K[A]TERINA VIRGO


Probably in the sacristy of the church of San Miniato al Monte, Florence, from whence the triptych may have been removed shortly after 1830.[1] Bertram Ashburnham [1797-1878], 4th earl of Ashburnham, Ashburnham Place, Battle, Sussex;[2] by inheritance to his son, Bertram Ashburnham [1840-1913], 5th earl of Ashburnham, Ashburnham Place; by inheritance to his daughter, Lady Mary Catherine Charlotte Ashburnham [1890-1953], Ashburnham Place; (Robert Langton Douglas, London);[3] purchased 19 June 1919 by (Duveen Brothers, Inc., London, New York, and Paris);[4] sold 15 December 1936 to The A.W. Mellon Educational and Charitable Trust, Pittsburgh;[5] gift 1937 to NGA.

Exhibition History
Italian Paintings of the XIV to XVI Century, Detroit Institute of Arts, 1933, no. 11, repro., as Altarpiece by Gherardo Starnina.
Venturi, Lionello. Pitture italiane in America. Milan, 1931: no. 52, repro.
Procacci, Ugo. "Gherardo Starnina." Rivista d’arte 15 (1933): 160.
Valentiner, Wilhelm R. "Die Leihausstellung frühitalienischer Malerei in Detroit." Pantheon 12 (1933): 238.
Valentiner, Wilhelm R., ed. The Sixteenth Loan Exhibition of Old Masters: Italian Paintings of the XIV to XVI Century. Exh. cat. Detroit Institute of Arts. Detroit, 1933: no. 11, repro.
Venturi, Lionello. Italian Paintings in America. Translated by Countess Vanden Heuvel and Charles Marriott. 3 vols. New York and Milan, 1933: 1:no. 63, repro.
Salvini, Roberto. "Per la cronologia e per il catalogo di un discepolo di Agnolo Gaddi." Bollettino d’arte 29 (1935-1936): 287.
Duveen Brothers. Duveen Pictures in Public Collections of America. New York, 1941: no. 24, as by Gherardo Starnina.
National Gallery of Art. Book of Illustrations. Washington, 1941: 104 (repro.), 233.
Preliminary Catalogue of Paintings and Sculpture. National Gallery of Art, Washington, 1941: 69, no. 4.
Richter, George Martin. "The New National Gallery in Washington." The Burlington Magazine for Connoisseurs 78 (June 1941): 177.
Book of Illustrations. National Gallery of Art, Washington, 1942: 239, repro. 106.
Friedmann, Herbert. The Symbolic Goldfinch. Its History and Significance in European Devotional Art. Washington, DC, 1946: 143.
Paintings and Sculpture from the Mellon Collection. National Gallery of Art, Washington, 1949 (reprinted 1953 and 1958): 8, repro.
Galetti, Ugo, and Ettore Camesasca. Enciclopedia della pittura italiana. 3 vols. Milan, 1951: 3:2351 repro.
Labriola, Ada. "Gaddi, Agnolo." In Dizionario biografico degli italiani. Edited by Alberto Maria Ghisalberti. 82+ vols. Rome, 1960+: 51(1998):146.
Berenson, Bernard. Italian Pictures of the Renaissance. Florentine School. 2 vols. London, 1963: 2:69.
Summary Catalogue of European Paintings and Sculpture. National Gallery of Art, Washington, 1965: 54.
Klesse, Brigitte. Seidenstoffe in der italienischen Malerei des 14. Jahrhunderts. Bern, 1967: 316.
Boskovits, Miklós. "Some Early Works of Agnolo Gaddi." The Burlington Magazine 110 (1968): 210 n. 9.
European Paintings and Sculpture, Illustrations. National Gallery of Art, Washington, 1968: 46, repro.
Cole, Bruce. Agnolo Gaddi. Ph.D. diss. Bryn Mawr College, 1969. Ann Arbor, MI, 1977: 73-75, 85, 208, 209.
Boskovits, Miklós. "Gaddi, Agnolo." In Dizionario Enciclopedico Bolaffi dei pittori e degli Incisori italiani: dall’XI al XX secolo . Edited by Alberto Bolaffi and Umberto Allemandi. 11 vols. Turin, 1972-1976: 5(1974)186.
Fredericksen, Burton B., and Federico Zeri. Census of Pre-Nineteenth Century Italian Paintings in North American Public Collections. Cambridge, Mass., 1972: 77, 301, 315, 369, 378, 381, 645.
Fraser, Ian, Edith Whitehill Clowes, George Henry Alexander Clowes, and Carl J. Weinhardt. A Catalogue of the Clowes Collection. Indianapolis Museum of Art Bulletin. Indianapolis, 1973: 6.
Boskovits, Miklós. Pittura fiorentina alla vigilia del Rinascimento, 1370-1400. Florence, 1975: 118-121, 123, 216 n. 84, 234 n. 140, 304, pl. 127.
European Paintings: An Illustrated Summary Catalogue. National Gallery of Art, Washington, 1975: 140, repro.
Fremantle, Richard. Florentine Gothic Painters from Giotto to Masaccio: A Guide to Painting in and near Florence, 1300 to 1450. London, 1975: 271, fig. 553.
Cole, Bruce. Giotto and Florentine Painting, 1280-1375. Icon Editions. 1st ed. New York, 1976: 140, 141, pl. 52.
Cole, Bruce. Agnolo Gaddi. Oxford, 1977: 26-30, 40, 41, 89, pls. 81, 82.
Boskovits, Miklós. "Review of Agnolo Gaddi by Bruce Cole." The Art Bulletin 60 (1978): 708.
Shapley, Fern Rusk. Catalogue of the Italian Paintings. National Gallery of Art. 2 vols. Washington, 1979: 1:192-194; 2:pl. 134.
Sutton, Denys. "Robert Langton Douglas. Part III." Apollo 109 (June 1979): 447 [165] fig. 1, 452 [170].
Os, Hendrik W. van. Sienese Altarpieces 1215-1460. Form, Content, Function. 2 vols. Groningen, 1984-1990: 2(1990):66, fig. 48.
Walker, John. National Gallery of Art, Washington. Rev. ed. New York, 1984: 73, no 16, color repro.
Brown, Howard Mayer. "Catalogus. A Corpus of Trecento Pictures with Musical Subject Matter, pt. 2." Imago Musicae 2 (1985): 200, 201.
European Paintings: An Illustrated Catalogue. National Gallery of Art, Washington, 1985: 162, repro.
Ford, Terrence, compiler and ed. Inventory of Music Iconography, no. 1. National Gallery of Art, Washington. New York 1986: 1, no. 5.
Ricci, Stefania. "Gaddi, Agnolo." In La Pittura in Italia. Il Duecento e il Trecento. Edited by Enrico Castelnuovo. 2 vols. Milan, 1986: 2:572.
Causa, Stefano. "La Sagrestia." in La Basilica di San Miniato al Monte a Firenze. Edited by Francesco Gurrieri, Luciano Berti and Claudio Leonardi. Florence, 1988: 228, 229.
Bellosi, Luciano. "Gaddi, Agnolo." In Dizionario della pittura e dei pittori. Edited by Enrico Castelnuovo and Bruno Toscano. 6 vols. Turin, 1989-1994: 2(1990):471.
Boskovits, Miklós, and Serena Padovani. The Thyssen-Bornemisza Collection: Early Italian Painting 1290-1470. London, 1990: 116 n. 1.
Chiodo, Sonia. "Gaddi, Agnolo." In Allgemeines Künstlerlexikon: Die bildenden Künstler aller Zeiten und Völker. Edited by Günter Meissner. 87+ vols. Munich and Leipzig, 1992+: 47(2005):113, 114.
Skaug, Erling S. Punch Marks from Giotto to Fra Angelico: Attribution, Chronology, and Workshop Relationships in Tuscan Panel Painting with Particular Consideration to Florence, c. 1330-1430. 2 vols. Oslo, 1994: 1:262, 263; 2:punch chart 8.2
Frosinini, Cecilia. "Agnolo Gaddi." in La Sacra Cintola nel Duomo di Prato. Prato, 1995: 226.
Halpine, Susana M. "An Investigation of Artists' Materials Using Amino Acid Analysis: Introduction of the One-Hour Extraction Method." Studies in the History of Art 51 (1995): 41-48, 61, repro. no. 7, 64-65 nn. 41-55.
Skerl Del Conte, Serena. Antonio Veneziano e Taddeo Gaddi nella Toscana della seconda metà del Trecento. Pasian di Prato (Udine), 1995: 52-54, 56, 62, 65 n. 13, 66 n. 23, repro.
Gold Backs: 1250-1480. Exh. cat. Matthiesen Fine Art, London. Turin, 1996: 80.
Symposium, Early Italian Paintings Techniques and Analysis, Maastricht, 1996: 81, repro.
Bakkenist, Tonnie, René Hoppenbrouwers, and Hélène Dubois, eds. Early Italian Paintings: Techniques and Analysis. Maastricht, Netherlands, 1997: 81, repro.
Bustin, Mary. "Recalling the Past: Evidence for the Original Construction of Madonna Enthroned with Saints and Angels by Agnolo Gaddi." Studies in the History of Art 57 (1997): 35-64, repro. no. 2.
Halpine, Susana M. "Analysis of Artists’ Materials Using High-Performance Liquid Chromatography." In Early Italian Paintings: Techniques and Analysis. Edited by Tonnie Bakkenist, René Hoppenbrouwers and Hélène Dubois. Maastricht, Netherlands, 1997: 22, 23.
Frinta, Mojmír S. Punched Decoration on Late Medieval Panel and Miniature Painting. Prague, 1998: 100, 244, 283, 290, 322, 481.
Labriola, Ada. “La decorazione pittorica.” In L’Oratorio di Santa Caterina: osservazioni storico-critiche in occasione del restauro. Edited by Maurizio De Vita. Florence, 1998: 52.
Merzenich, Christoph. Vom Schreinerwerk zum Gemälde: Florentiner Altarwerke der ersten Hälfte des Quattrocento. Berlin, 2001: 89, 189, fig. 49.
Weppelmann, Stefan. Spinello Aretino und die toskanische Malerei des 14. Jahrhunderts. Florence, 2003: 184.
Hand, John Oliver. National Gallery of Art: Master Paintings from the Collection. Washington and New York, 2004: 11, no. 6, color repro.
Medicus, Gustav. "Gaddi, Agnolo." In Medieval Italy: An Encyclopedia. 2 vols. Edited by Christopher Kleinhenz. New York, 2004: 1:393
Secrest, Meryle. Duveen: A Life in Art. New York, 2004: 438.
Skaug, Erling S. "Towards a Reconstruction of the Santa Maria degli Angeli Altarpiece of 1388: Agnolo Gaddi and Lorenzo Monaco?" Mitteilungen des Kunsthistorischen Institutes in Florenz 48 (2004): 255.
Boskovits, Miklós, and Daniela Parenti, eds. Da Bernardo Daddi al Beato Angelico a Botticelli: dipinti fiorentini del Lindenau-Museum di Altenburg. Exh. cat. Museo di San Marco. Florence, 2005: 80.
Sander, Jochen. "The ‘Standard Altarpiece’ of the Gothic Period: The Polyptych." In Kult Bild: das Altar- und Andachtsbild von Duccio bis Perugino. Exh. cat. Städelsches Kunstinstitut, Frankfurt am Main. Petersberg, 2006: 95, 96.
Löhr, Wolf-Dietrich, and Stefan Weppelmann, eds. Fantasie und Handwerk: Cennino Cennini und die Tradition der toskanischen Malerei von Giotto bis Lorenzo Monaco. Exh. cat. Gemäldegalerie, Berlin. Munich, 2008: 291.
Boskovits, Miklós, ed. The Alana Collection, Newark, Delaware, USA. Vol. 1 (of 2), Italian Paintings from the 13th to 15th Century. Florence, 2009: 1:4, repro. 10.
Damiani, Giovanna, ed. Le arti a Firenze tra gotico e Rinascimento. Exh. cat. Museo Archeologico, Aosta. Florence, 2009: 76.
Tartuferi, Angelo, ed. L’Oratorio di Santa Caterina all’Antella e i suoi pittori. Exh. cat. Santa Caterina dell’Antella, Bagno a Ripoli-Ponte a Ema. Florence, 2009: 159.
Boskovits, Miklós, and Daniela Parenti, eds. Cataloghi della Galleria dell’Accademia di Firenze: Dipinti. Vol. 2, Il tardo Trecento: dalla tradizione orcagnesca agli esordi del gotico internazionale. Florence, 2010: 16.
Gordon, Dillian. The Italian Paintings Before 1400. National Gallery Catalogues. London, 2011: under 220, no. NG568.
Technical Summary

This panel, along with its companions Saint Andrew and Saint Benedict with the Archangel Gabriel [left panel] and Madonna and Child Enthroned with Twelve Angels, and with the Blessing Christ [middle panel], are formed from vertically oriented poplar planks.[1] The two companion panels are formed of three vertical planks each, with narrower strips of wood flanking the central plank, while the panel of this work is formed of two boards of equal width, joined vertically between the two saints. The main panels of the altarpiece are 4 to 4.5 cm thick; the frame supplies an additional thickness of 2.7 to 2.9 cm for the flat molding and 2.3 cm for the dentil molding. On the reverse, the panels are reinforced with modern horizontal battens set into grooves. The two absent original battens, spanning all three panels, were placed along the bottom and just below the base of the gabled tops of each panel, as is clear from the remains of large nails used to attach them that are visible in the x-radiographs. The frame, which consists of an additional plank of wood that completely covers the gable portion of the panels, contains pastiglia decoration. The columns dividing the central and lateral panels and flanking the outer edge of the laterals are missing, as well as the freestanding cusped arches originally lining the ogival arches of the panels. The wooden support is covered by a gesso ground spread over a fabric interlayer. Incised lines in the gesso outline the figures and the fold lines in the drapery. The gold ground was applied over a red bole preparation. The halos are decorated by stamped and engraved motifs as well as stippling.

Outlines of areas to be painted and drapery fold lines were further delineated with brushed underdrawing, which is visible with infrared reflectography.[2] The paint is mostly egg tempera, but select pigments are bound with glue.[3] Flesh areas are painted with the traditional underlayer of green. The pattern of the orientalizing carpet on which the figures stand was transferred from a stencil to the paint applied over burnished gold.[4] The wings of the seraphim are decorated using sgraffito to reveal the gold underlayer. The edges of the figures’ robes are decorated with mordant gilding.

All three panels retain their original thickness. Madonna and Child Enthroned has two major splits, one running from the lower edge into the mantle of the Virgin, the other diagonally across the wing of the uppermost right-hand angel. Saint Andrew and Saint Benedict has cracks caused by the removal of the original intermediate frame. Saint Bernard and Saint Catherine has a split at the lower edge and another in the frame to the left of and above the Virgin Annunciate in the gable medallion. Worm tunneling is present in all three panels, but it is most extensive in the side planks of Saint Andrew and Saint Benedict and Madonna and Child Enthroned as well as in the gables of all three panels. There is minor abrasion of the paint film in the faces and hands, but otherwise the painted surface is in fine condition. The red lakes of the robes of Saint Catherine, the kneeling angels, and the Christ child have faded slightly, and the Virgin’s blue robe is worn. The altarpiece underwent conservation treatment between 1988 and 1991,[5] in the course of which the now lost intermediate columns between the three panels were reconstructed.[6] Also during this treatment, some of the fold lines in the Virgin’s robe were recreated.