History of the frescoes' origins, damage to them, and restoration work

1750	Tiepolo arrives in Würzburg in December.
1751/52	Fresco decoration of the Kaisersaal (Imperial Hall) on the vaulting and in the upper area of the walls.
1752/53	After the Kaisersaal, Giambattista Tiepolo and his assistants subsequently fresco the barrel vaulting in the staircase. At the same time, Antonio Bossi carries out the stucco work for the corner figures above the main cornice.
1753	After completing the frescoes, Tiepolo returns to Venice in November.
1765	Stucco work on the walls of the staircase by Lodovico Bossi. Closure of the upper round windows on the west side in the process, reducing the natural lighting of the fresco.
1774	Manufacture by Materno Bossi of the large central chandelier in the staircase.
1805	Possible restoration of the ceiling paintings in the Residence by Caspar Carl Fesel. Scharold reports that ‘the ceiling painting … was recently overpainted by his hand and freshened up with commendable skill’ (K.G. von Scharold, Materialien zu einer fränkischen Kunstgeschichte, Würzburg University Library M.ch.f.636, fol. 217v). It is questionable whether this affected Tiepolo’s frescoes.
Pre-1840	Damage due to damp caused by leaky roof and cornice coverings had apparently occurred, requiring ‘very thorough maintenance work on the roof, mainly involving the restoration, completed in 1840, of the main external stone cornice extending along the staircase’ (letter of 18 August 1843 from Klenze to King Ludwig I, Principal State Archives of Bavaria, Munich [BayHStA München], SchlV no. 1154).
1840	Report of dark spots on the staircase fresco; consideration is given to carrying out restoration work and selecting suitable specialists (Bay. HStA Munich, SchlV no. 1154).
1843	Klenze recommends that some minor sample cleaning should be carried out ‘using bread, tow and other drying substances’ in order to ‘cause the least possible impairment of the originality of the frescoes’, particularly since no further expansion of the darkened areas had been observed for some two years (Bay. HStA Munich, SchlV no. 1154).
1847	An examination is carried out by Schubert, a professor of chemistry, and the painter Andreas Geist at two different points, which are unfortunately not precisely described. There is mention of grey-black spots causing blurring of all the shadows and darkening of the light sides, and these are described as involving mouldy, rather ‘cryptogamic’ vegetation. An attempt to remove the spots by rubbing them with black bread is unsuccessful. ‘By contrast, a further  attempt involving washing them off with diluted sal ammoniac spirit, which was carried out on several places and on different colours, produced a favourable result’ (Bay. HStA Munich, SchlV no. 1154). However, a complete restoration was apparently not carried out (T. Marr, 1997, p. 159).
1896	A fire in the north wing of the Residence spreads to the roof of the Kaisersaal, but the roof of the staircase is spared. As a result of fire-fighting operations, substantial amounts of water penetrate the vaulting and lead to the formation of spots. A new roof is erected over the Kaisersaal as quickly as possible, but the frescoes are not restored.
1919	Max Doerner (of the Academy of Fine Arts in Munich) urges that damage to the staircase fresco should be repaired.
1920/21	Erection of scaffolding on the east side of the staircase ‘near the camel group’ and examination of the damage. Recommendation that a ventilation hole should be created in the vaulting and that the fresco plaster and loose particles of paint, as well as layers of paint showing powdering, should be strengthened (letter from G. Hager to the Bavarian Crown Property Administration, 14 October 1921, BSV, 385I fasc. 3).
1923	Two lateral ventilation holes are inserted into the apex of the staircase vaulting.
1929	A piece of plaster that had fallen out of the small original central opening in the staircase vaulting (for the chandelier cord) is replaced and painted to match the surrounding fresco.
1944	It is reported that various minor areas of damage to the Tiepolo frescoes were already present in 1944 (photographic documentation by C. Lamb), in which the parts with al secco overpainting had crumbled away. ‘This mainly affects the purple, as in the coat of the Duke of Burgundy in the marriage picture; the underpainting for the whole robe formed a deep grey-violet, painted wet in wet and made of caput mortuum, which was left open at the sleeves. Similar damage was also evident in other purple areas, such as the drapery on America and the camel’s caparison’ (M. von Freeden and C. Lamb, 1956, Chapter IX, note 4).
1944/45	Extensive photographic documentation of the Würzburg Residence by Carl Lamb, including colour photos. These already show sometimes substantial collections of biogenic substances (moulds), particularly in the staircase fresco. In addition, traces of salification and cleaning are visible.
1945	All of the building’s roofs are destroyed during a heavy air raid on 16 March. The baroque roof-trusses over the central building are destroyed by fire. The tremendous heat leads to the formation of quicklime on the surface of the tuff vaulting over the staircase, as well as ‘splitting off of the plaster in larger areas’ (O. Hertwig, 1952, p. 57). During later heavy rainfall, water collects between the vaulting and the exterior walls, saturating the masonry and frescoes. Slaked quicklime penetrates the vaulting in the form of calcium hydrate, leading to ‘glazing’ of the fresco in some parts. Some protection against further water exposure is initially provided with tarpaulin covers, and with emergency roofing from the summer onwards. Detachment of the paint surface takes place in the depictions of the Continents in the staircase. Postwar photographs confirm substantial blackening of the surface. Max von Freeden recalled tube-like fungal bodies hanging down at this time, increasingly disfiguring the painting (M. Staschull, 1996, p. 290).
1945/46	Restoration of the roof over the Kaisersaal, the iron roof-truss of which (post-1896) had survived.
1947	In May, Dr. Stois of the Doerner Institute and Karl Tutschek, a restorer, examine the southern part of the fresco in the staircase. In his report, Stois describes the poor state of the fresco. The damage ‘principally consists of raising and (in parts) dropping away of the paint layers following painting contours, and extreme and sometimes vigorous formation of spots and bubbles. In areas of this type, the paint layers are either only loose and sagging or lie as a decomposing, more or less powder-like substance on the painting ground, which is however still firm and apparently unaltered. The appearance of salt-like efflorescences partly veiling the paint, and of brownish-black, point-like and radiating fungal growths, sometimes in large numbers, lying on the surface of the painting reinforce the impression here of vigorous and advanced destruction’ (Doerner Institute, Munich, report of 4 August 1947). The restorers Tutschek and Gramberger carry out protection and restoration work on the frescoes in the Kaisersaal. ‘Initially this involved re-gluing films of the paint layer in areas of severe damp that were in some places raised like bubbles and in others were already hanging down in shreds over worn plaster. This was mostly completed during the summer … in extremely laborious, painstaking and detailed work by injecting lime casein water with injection needles’ (O. Hertwig, 1952, p. 57). In a scaffolding accident in September, Tutschek is killed and Gramberger is seriously injured; restoration work stops.
1948/49	Erection of a steel roof-truss and roofing over the staircase.
1948/49	Restoration of the staircase fresco by Johann Drobek and Ludwig Gramberger, who has in the meantime recovered. Drobek organizes and directs this extensive and complex process, taking samples of the plaster and paint and carrying out strengthening experiments using sinter water, lime casein, glutin and immunin, a synthetic resin emulsion (M. Staschull, 1996, p. 293). ‘Once split areas of plaster had been attached with plugs and the dangerous magnesium sulphate and other efflorescences in worn locations had been converted into insoluble barium compounds using barytes water, very successful hardening and strengthening of the extensive impasto paint layers was carried out using lime-water … The only places where it was not possible to carry out this procedure were certain areas of intensive painting … as veils disturbing the brilliance of the paint started to emerge in test areas. Soiling on firmly attached fresco surfaces and veiling caused by lime was capable of being washed off with distilled water and soft sponges, with ammonia or ethyl acetate being added if needed. The black fungal formations were quite easily brushed off; the formalin used to harden the paint layer temporarily also helped annihilate these. The use of lime casein was then completely abandoned, as there seemed to be a danger of it overbinding … Wherever fast gluing was needed, glutolin and carefully dosed immunin were therefore used along with lime-water (O. Hertwig, 1952, pp. 59–60).
1950	Restoration of the ceiling painting in the Kaisersaal is completed in October. ‘The green grisaille paintings in the southern window niches have yet to be done, mainly by Mr. Gramberger, while Mr. Drobek needs to take care of himself and if the colder weather starts now, will have to abandon working in the Kaisersaal’ (letter from Otto Hertwig, 6 November 1950, Buildings File of the Würzburg State Dept. of Building/State Dept. of Construction and Civil Engineering).
1951	Paint samples are taken from the wall covering in the staircase; completion of restoration and reconstruction work in the fresco and stucco area of the Kaisersaal; the first postwar Mozart Festival is held.
1960s	Fresh damage becomes evident in the staircase fresco.
1964-1966	Structural safety work in the vestibule and Weisser Saal (White Hall), also affecting the south wall of the staircase; the double columns at the entrance to the staircase are converted into buttresses.
1966/67	Preliminary examinations, paint samples and renovation of the walls of the staircase.
1968	Salt damage to the staircase fresco (in the depiction of Africa) is ‘treated’.
1995	Extensive documentation of damage and taking of samples for microbiological examination, analysis of pigments, binder, salt and plaster, as well as emergency strengthening of plaster areas at high risk of falling out and of paint patches in the staircase fresco. Preparation of various strengthening samples. A specialist colloquium is held to present the state of the damage and discuss further procedures.
1996-1998	Studies of air conditions in the Kaisersaal and staircase.
1997/1998	Extensive documentation of damage and taking of samples for analysis of pigments, binder, salt and plaster, as well as emergency strengthening of plaster areas at extreme risk of falling out and of paint patches in the Tiepolo frescoes in the Kaisersaal.
1999-2001	Analysis of the air condition measurements, development of overall restoration concepts, and establishment of a budgetary framework during preparations for overall restoration.
2002	Approval of the budgetary framework by the Bavarian State Parliament, preparations for assembling a suitable team of restorers, re-erection of the improved bridge scaffolding from 1995, additional preliminary studies (analysis of the 1995 strengthening pattern, macroscopic reexamination of selected damage sites from 1995, ultraviolet studies, thermographic and sonographic studies, taking of samples, etc.)
Februar 2003	Formation of a working group of specialist restoration and scientific consultants, checking of the statics of the vaulting shell in the staircase, re-mapping of cracks and gaps, etc.
April 2003	Official start of restoration work on the staircase fresco.