An account of the condition, conservation, materials and techniques
Arthur Lucas and Joyce Plesters
In the first issue of the ‘National Gallery Technical Bulletin’, which appeared in September 1977, the case-histories given in detail were all of pictures which had very recently undergone examination and treatment. In the present issue it was considered that it might be of some general interest to review the case-history of a picture the most recent restoration of which dates from over ten years ago, Titian's ‘Bacchus and Ariadne’ (No.35), indisputably one of the finest and most famous of all the National Gallery's paintings. At the time the matter of whether the picture ought or ought not to be cleaned became something of a ‘cause célèbre’. It may be that with a decade separating both authors and readers from the event, and passions in the meantime having somewhat cooled, it will be easier to present an objective account.
The history, iconography and provenance of Titian's ‘Bacchus and Ariadne’ are given in detail by Cecil Gould in his National Gallery Catalogue, ‘The Sixteenth Century Italian Schools’(note 1), and in a monograph (note 2) published in 1969 on the occasion of the picture being re-exhibited after cleaning and restoration. It suffices here to say that originally it formed one of a series of paintings of Bacchanalian subjects commissioned by Duke Alfonso I d'Este of Ferrara and was finished by Titian in 1523.
Before its most recent conservation treatment, carried out between 1967 and 1969, the ‘Bacchus and Ariadne’ was seen to be considerably darker and more discoloured than the two companion 'Bacchanals' by Titian, the ‘Worship of Venus’ and the ‘Bacchanal of the Andrians’, both in the Prado, Madrid, although they were, and still are, by no means free from old and yellowed varnish. This in itself might have constituted a valid argument in favour of cleaning the ‘Bacchus and Ariadne’, but, as we shall see, was not the decisive factor in electing for cleaning, that being the physical safety and preservation of the picture as a whole. Varnish removal proved to be a necessary preliminary stage in a complete programme of conservation.
The decision which had to be made as to whether or not to treat the picture has to be seen in the context of the mid-1960s. The early sixties had witnessed a renewal of the 'cleaning controversy' which had raged from time to time in connection with the National Gallery ever since the 1840s. A late offshoot of the 1960s controversy was a series of letters written in 1966 (note 3), some addressed to the Director or Keeper of the National Gallery, others published in ‘The Times’, on the subject of possible future cleaning of the picture. Although the major part of the correspondence constituted a plea for cleaning, there was a predictable hard core of objectors. In April 1967 the Trustees of the National Gallery considered a report by the Chief Restorer, Arthur Lucas, on the condition and an outline of his proposals for treatment. It was decided, however, that an international committee should be set up to advise on any proposed treatment before it was put into practice. The committee (note 4) sat between 22 and 24 April 1967. Their report (note 5), dated 24 April, concluded that the condition of the picture urgently required treatment and that that proposed by the Chief Restorer was appropriate and desirable, with cleaning, in the sense of varnish removal, as an integral part. The Chief Restorer began the task in 1967, completing it in 1969.
History of condition and treatment before 1967
The earlier history of the picture is not without relevance to the disorders which compelled its most recent restoration. Titian began the picture in Venice in 1520 or 1522 and finished it at Ferrara early in 1523, the unfinished canvas having been sent by sea from Venice to the port of Ferrara. In 1598 the picture was transferred from Ferarra to Rome. It was not unusual in the past (and in Venice even today is still often essential) to take a canvas painting off its stretcher and roll it up for ease of transport whether on human- or horseback, by waggon or boat. This operation, particularly if the canvas is rolled into a cylinder of small diameter or rolled with the paint layer innermost, can be very injurious to both paint and ground layers. It would be quite likely to cause both vertical cracks and horizontal cleavage in a rather brittle material like gesso (a form of calcium sulphate bound with animal glue, which was in fact identified as the ground of the ‘Bacchus and Ariadne’). The many small losses noted in the paint layers coupled with the disintegrating state of the gesso ground before its recent consolidation are not inconsistent with rolling of the painted canvas combined with rough handling m transit. The third major journey which the picture underwent was to London in 1806 or 1807. It was known that it was restored on arrival in London and was cleaned either then, or before it left Italy, or both. The English artist, Henry Bone, made a sizeable enamel copy of it which was certainly in existence by 1811, when it was remarked on by Joseph Farington in his diary (note 6). The enamel was exhibited alongside the newly-cleaned original in 1969 and it was remarkable, making only a small allowance for difference of painting medium and possible slight alterations during firing of the enamel, how closely the colours of enamel and newly-cleaned picture coincided. Enamel colours are not normally subject to the discolouring effects of light and atmosphere to which easel paintings, particularly when varnished with natural resin varnishes are prone. The close similarity in colours of the newly-cleaned picture in 1969 and Henry Bone's enamel, which he must have completed a little before 1811, also implies that when the enamel copy was made the original had just undergone, in about 1806 or 1807, as complete a removal of discoloured varnish as in its most recent cleaning. Unfortunately, even up to twenty-five years ago, by which time modern less-yellowing (or even non- yellowing) synthetic resin varnishes had become readily available, newly-cleaned paintings had to be revarnished using the same type of natural resin varnish as that just removed, the most common being mastic resin dissolved in turpentine distillate, with or without the addition of a drying oil such as linseed. (Happily, cases of the use of varnishes based on resins like copal or amber dissolved in drying oils by heating are comparatively rare on pictures cleaned within our time, which is fortunate, since with age they may become extremely difficult to remove; their removal in the past by harsh methods may have been responsible for damage to some pictures.)
Although a varnish of natural resin in a volatile solvent, such as mastic in turpentine, when initially applied in a thin coat imparts no perceptible colour to a picture, it may, with age and exposure, begin to show signs of discolouration in as little as twenty years and eventually the cycle of varnishing and cleaning, cleaning and varnishing would begin all over again. By the time the ‘Bacchus and Ariadne’ was bought for the National Gallery in 1826 it is recorded that the varnish had already begun to turn brown. Twenty years later it was cleaned, but only partially, and re- varnished with a mastic varnish containing a proportion of linseed oil.
It is not known when the first lining canvas, i.e. a new canvas stuck to the back of the old for the purpose of reinforcing the latter, was applied. Almost all canvas paintings of any appreciable age or value are found to have been lined at one time or another. By 1894 the existing lining canvas was reported to be in a bad state and a double lining canvas was substituted which in turn was replaced by a single one in 1929, this last mentioned being the canvas removed in the 1967–1969 restoration. Apart from simple mechanical reinforcement of the exceptionally thin and finely-woven original canvas (see p.38 and Fig.7), the main object of these repeated lining and relining operations on the ‘Bacchus and Ariadne’ would have been to try to obtain better cohesion between the various layers of paint, ground and canvas. It is likely that the thin gesso ground on which the picture is now known to have been painted had long ceased to adhere completely either to the canvas or paint. Deterioration of the gesso ground could have been hastened by the action of water, either in leaching out the glue medium of the gesso or by providing suitable conditions for biological attack by micro-organisms. In fact, in a letter to the Select Committee on the National Gallery of 1853, William Buchanan, through whose hands the picture had passed in 1806, states that he was informed 'that water had been freely used in taking away some surface dirt' and expressed the view that it would have penetrated through cracks and fissures in the surface into the absorbent gesso ground, eventually causing 'the body of the paint itself [. . .] to scale off' (note 7). It is not, however, clear from the context exactly when he believed this cleaning with water to have taken place.
The National Gallery is singularly fortunate in having records of condition and restoration going back to the beginnings of the collection. For much of the earlier data we have to thank Sir Charles Eastlake, the first Director of the National Gallery, who meticulously recorded condition and treatments of pictures as they were acquired in his Manuscript Catalogue, the first volume of which he began in 1856. His example encouraged his successors to keep up similar technical records.
In the case of the Titian ‘Bacchus and Ariadne’ some relevant documentary evidence survives even from before the painting's acquisition. It might be of interest to give a summary of the picture's history of restoration, from documentary and published sources, up to the examination and treatment of 1967–1969:
Irvine wrote to Buchanan from Rome that Day, who had recently bought the picture from the Aldobrandini Palace, intended to have it cleaned (note 8).
Farington records remarks by Benjamin West, PRA: 'He said the picture was really in a fine preservation, but it was mortifying to see that Burch, the picture dealer, had been putting colour upon it, in many parts – upon the sky with ultramarine – and had stippled colour upon parts of the flesh. He said if the picture was his he would take off the whole of what Burch had done, for he knew he was the person that had done it in order to make the picture appear more showy; he knew his hand (note 9)'.
Picture purchased by the Gallery.
The journal ‘News of Literature and Fashion’ for the 15 April of that year remarks: 'The real truth is that the ‘Bacchus and Ariadne’ has had a great many tricks played with it. When at Rome, it was considered a fine picture, but exceedingly brown. When it came to England it was cleaned so effectually as to have become a perfectly blue picture, and now it has relapsed into dinginess again [...] .
Eastlake's initial entry for the picture in the Manuscript Catalogue concerning conservation: 'Lined: at what period uncertain. Cleaned to a certain extent by Mr. J. Seguier (note 10) in October 1846. See Return respecting pictures cleaned; Report from the Select Committee on the National Gallery, 1853, p.748. See also minutes of the Trustees (Parliamentary Paper No.40,1847, pp.15,19) – Gallery Varnish 1846' (note 11).
'Discoloured and decayed varnish removed so far as was thought prudent.' (Appendix to ‘Report from the Select Committee on the National Gallery’, 1853.) The remark refers to Seguier's cleaning operation of 1846 mentioned above. Before the Select Committee Mr. Retra Bolton, a picture-cleaner, stated his belief that the 'Bacchus' had been hurt by the Gallery Varnish: 'I remember that picture looking fresher a great deal. I do think the oil varnish has acted upon that picture: it is getting streamy and smurky [sic] about the skies.'
Reported as having been lined, at what period uncertain. Repairs visible in the left shoulder, neck and breast of Bacchus. Effects of discoloured varnish (probably not completely removed in 1846) apparent in the sky, 'but not so as to injure the appearance'. Canvas partially detached from the lining in the upper left corner, also in the upper right corner.
Placed under glass.
The varnish revived by the Pettenkofer process (note 12).
'The picture was examined as to the "buckling" in the upper left-hand corner in August; the lining canvas being reported by Morrill (note 13) to be in a bad state, the picture was relined [double lined by Morrill, for which the bill exists in the Conservation Department's files]. The surface of the varnish was then taken off by Buttery with the finger (note 14), one or two very slight injuries repaired, and the picture was re-varnished with mastic, under my eyes' [signed E.J. POYNTER (note 15) ].
The two lining canvases removed by Morrill revealing that the back of the original canvas 'had at some period been covered with paint' [which was probably in fact an old adhesive, containing some lead white, from an even earlier lining]. Relined with a single canvas. The then Director, A. M. Daniel 'expressed the definite desire that the surface should be touched as little as possible, as I in no way wished the picture to be cleaned nor the old varnish to be removed', in spite of a warning from the restorer that in the process of relining the varnish 'might perish and become opaque'.
The new lining seems not to have been a success, for there exists pasted in the Manuscript Catalogue a further typewritten note signed by A. M. Daniel describing how, while Mr Morrill the restorer had been gluing the original canvas onto the lining, a blister had formed on the foreground beneath the feet of one of the Bacchante. Morrill had considered the only course to adopt-though some might consider it a drastic one-was to cut the blister, thereby releasing the pressure within, 'before it spread further'. This cut, through the original canvas and about 14 inches long, could easily be seen (Fig. 1) before the 1967–1969 restoration. Morrill was strongly of the opinion-and his views were to be confirmed during the most recent examination and treatment of the picture-that the root of the trouble was the thin coat of paint, or paint-like material, on the back of the original canvas, which prevented 'the proper action of the glue in making at once adherent the original canvas and the lining'.
Unfortunately the recurring malady of flaking paint seems not to have been cured in the long-term by this latest relining:
June and November. Flaking paint secured by Morrill.
Loose paint laid by Morrill.
Polished by Vallance (note 16).
Varnish along right edge revived by Lucas.
Fine flaking at top treated with wax by Woods.
In 1938 a report on the state of the painting was made by H. Ruhemann, then Consultant Restorer, who after detailing the well-preserved areas, paint losses, damages and retouchings, concluded: 'Could be greatly improved, but it would be an enormous job'.
In 1948 a very full report of the condition at that time was made by Philip Hendy, then Director, in collaboration with conservation staff. The observations and proposals for treatment, including removal of old varnish, laying of loose paint, impregnation of ground and paint with an adhesive, probably combined with relining, were not in fact very different from those to be made in 1967. The optimistic tone of the report suggests that it was expected that the proposals would very soon be put into practice, but it was not to be. In 1947–1948 there was held the 'Cleaned Pictures Exhibition' consisting of all the National Gallery pictures cleaned since 1936 (a total of seventy works), together with related photographs and background information, and catalogue (note 17). To some (including the authors) the 'Cleaned Pictures Exhibition' was a revelation; to others it was an outrage. It has to be recalled that this comparatively small group of cleaned paintings at that time stood out like beacons among the rest of the collection, many of which still bore the notorious 'Gallery Varnish' (note 11), and against the rather dingy post-war decor. Moreover, several generations of Gallery visitors had grown up accustomed to seeing pictures in an uncleaned state. The position is now reversed, for not only in the National Gallery, but in a good many of the great galleries of the world and in major international exhibitions, it is the uncleaned pictures which tend disturbingly to stand out. Although an international committee, the Weaver Committee (note 18), set up in 1947 'to inquire into and report on the Safety of the methods and materials used in the cleaning of pictures at the National Gallery', affirmed that the safety of the pictures had never been jeopardized by cleaning, the storm of controversy subsided only gradually, leaving an atmosphere not conducive to starting on a major restoration of one of the Gallery's major masterpieces and the project was shelved until 1967. In the meantime anxiety about possible further deterioration of the painting did not, however, abate, for another longish report cataloguing the by now familiar symptoms of discoloured varnish, disfiguring retouchings, paint losses and further incipient flaking was entered in the Conservation Dossier in 1952.
Condition and treatment, 1967–1969
In April 1967 a new and thorough examination of the ‘Bacchus and Ariadne’ was made by the then Director (Sir Philip Hendy), the then Deputy Keeper (Cecil Gould) and the Chief Restorer (Arthur Lucas), who jointly worked out a programme of treatment.
Condition in 1967 before treatment
On this occasion assessment was greatly facilitated by a new set of X-radiographs covering the whole of the picture (Fig.2) and a set of full-sized infra-red photographs made at the same time (Fig.3). Infra-red radiation has the property of penetrating yellowed and semi-opaque varnish so that an infra-red photograph of an uncleaned picture will give a clearer image of the paint surface beneath than will an ordinary panchromatic photograph. At the stage of the examination at which cleaning tests were made these were supplemented by an equivalent set of full-size photographs taken by 'raking' light to show the surface texture (Fig.4).
The original canvas is remarkably thin and finely- woven (see p.38 and Fig.7), considering the relatively large size of the picture. In some past relining the turnovers and edges had been cut off close to the edge of the paint surface so that, as stuck down on the lining canvas, the cut edges of the original canvas lay within the edges of the stretcher. In the X-radiographs there can be seen some waviness in the weave of the original canvas towards the edges which must have been caused by uneven tension from the nails fastening it to its original stretcher (the existing stretcher probably dating only from 1894). The degree of damage to the original canvas could not easily be gauged before complete removal of the lining canvas, but the only conspicuous injury seemed to be the 14-inch long cut beneath the foot of the Bacchante with the cymbals which, as we have seen above, was deliberately made during the 1929 relining. Dark furrows seen in the X-radiographs which might be taken for rents in the canvas seemed more likely to result from irregularities in the thickness of the lining adhesive, or to be restricted to the paint layers. The reflected light photographs (Fig.4) show strikingly how the surface of the original canvas had become severely buckled and uneven as a result of past unsuccessful attempts at relining and shrinkage of old glue adhesives.
The lining canvas, dating from 1929, was in good condition as also was the layer of glue adhesive fixing the two canvasses together, but it was clear that the glue had not succeeded in penetrating the back of the original canvas. The relining operation had therefore failed to fulfil its primary intended function which was to impregnate and reattach loose ground and paint by the introduction of adhesive through the back of the original canvas.
The ground, which chemical analysis subsequently showed to be gesso (see p.33) appeared to be very thin and its attachment to both canvas and paint layer weak. In some areas of paint loss bare reddish-brown canvas was visible where the gesso ground had also fallen off.
The thickness, discolouration and reduced transparency of the varnish made judgement of the condition of the paint film difficult with the unaided eye. The X-radiographs (Fig.2) gave rather an alarming first impression. The numerous small losses in paint and ground (including those which have been filled in later with a chalk putty) appear as strongly-silhouetted black patches (those losses filled with lead putty appear as corresponding white patches). Although the initial impression from the radiographs was that a great deal of paint was lost, a rough calculation put the figure at about 5 per cent. Whilst this is by no means negligible it is not exceptional for a picture of the age of the ‘Bacchus and Ariadne’ (in fact, as will be seen below, the percentage as based on the X-radiographs proved to be rather an overestimate). The majority of the damages and retouchings seemed, from evidence from the picture itself, the X-radiographs and the infra-red photographs, to be in the top half of the composition, and for the most part in the sky. Individually the paint losses were not large. Of the figures, Bacchus seemed to have suffered most, having badly-discoloured retouchings on right arm, head and shoulder, but fortunately the damaged areas did not include the features of his face.
Most of the old retouchings had darkened from discolouration of the medium with age and exposure to light, but those on Bacchus's cloak showed as pale yellow spots through the discoloured varnish, presumably on account of a fugitive crimson-coloured pigment having been used in a past restoration.
The varnish, which was exceedingly thick and probably represents several successive varnishings, was very brittle, adhering in some places, but flaking in others. Microscopical examination of a sample revealed that as well as having become naturally discoloured with age, it had initially been deliberately tinted with brown and yellow pigment, probably the better to hide poorly-matching retouchings.Solubility tests on samples of the old varnish indicated that it was most likely to be mastic, but analysis by gas-chromatography (see p.37) detected the presence of a small addition of linseed oil (most probably added as a deterrent to 'bloom' developing on the varnish).
The next stage was to carry out some cleaning tests, removing the varnish from small selected areas of the picture. It was found that the varnish was easily soluble in solvent mixtures customarily used for removing old mastic/turpentine varnish, though on this occasion the mixture chosen was of 2-ethoxyethanol (1 part by volume), isopropanol (5 parts) and white spirit (refined turpentine substitute) (18 parts). The proportion of linseed oil in the varnish was obviously not sufficient to decrease its solubility to any marked extent. Nine cleaning tests were made, each of the order of about seven centimetres square. Those in the sky to the left of the picture not only showed more numerous paint losses, especially around the figure of Bacchus, than in cleaning tests elsewhere, but also some wearing of the top surface of the paint layer which had been disguised by roughly scumbling over with blue paint in an easily-soluble resinous medium. In other cleaning tests the paint seemed in remarkably good condition. The cleaning tests did reveal that paint and ground were flaking in small patches throughout the picture, but worst round the centre.
The cleaning tests can be seen in a colour photograph of the whole picture (Plate 4), which also gives a fair idea of the general tone before cleaning. The test in the sky above the centre of Bacchus's cloak was chosen as being representative of what was known to be the most damaged area. The one in the head and arms of the Bacchante with the tambourine shows that her dress is mauve, whereas in the uncleaned area it appeared grey. The one on the left leg and blue drapery of the Bacchante with the cymbals was in an area which had seemed from the infra-red photographs (Fig.3) to be much damaged and to have very disfiguring wide craquelure, but which on cleaning was revealed as reasonably well preserved. The tests in the lower right corner displays the almost perfect preservation of the iris, where, as in many other parts of the foliage in the picture, the green pigment has retained its colour and not become browned with age as in some other of Titian's works. A detail of the test on the yellow drapery beneath the urn in the bottom left corner is shown in Plate 2 (p.29).
At the time the cleaning tests were made (April 1967) it was noted in the dossier: 'Although the picture looks very blue in the cleaning test areas, it will not look so unbalanced in colour when it is cleaned completely, since the greens and carmine colours are well preserved and are not too brown. It was also added 'from the picture-restorer's point of view there are no serious problems other than a great number of holes to be filled in and painted out'.
Treatment proposed in 1967 and carried out between 1967 and 1969
The most important task to be done was to secure all loose paint and ground. It was clear that this would have to be carried out in several stages. Before work could commence on the back of the picture it was essential to stick a facing of paper to the front surface to protect and support the paint layer, but before that the old varnish would have to be removed since its brittleness and the fact that it was flaking away from the paint in some places would have made it impossible to achieve the firm bond which was essential between facing paper and paint film. It was emphasised that failure of previous linings to reinforce and reattach loose ground and paint could be traced to the imperviousness of the coating on the back of the original canvas. It would seem that Morrill in 1929 was probably aware of this, but did not dare scrape the back of the original canvas as clean as he would have liked for fear of the facing coming away, bringing the varnish with it and leaving the paint unsupported and loose, but, as was mentioned above, he was specifically forbidden by the then Director to remove the varnish. The success of any treatment was likely,to depend on thoroughly cleaning the back of the original canvas so that adhesive could be got through it to impregnate the weak gesso ground and so reattach the paint layers. A programme of treatment was designed around this basic concept.
The international committee
The international committee (4), already mentioned in the Introduction to this article, met on the 22–24 April 1967. The committee examined the picture and the relevant photographs and radiographs, and studied the report of the recent examination outlined above and a report from the Scientific Department. The Chief Restorer elaborated his proposals for treatment and he and other of the National Gallery staff were questioned on various aspects. The committee recorded that, for entirely satisfactory protection of the picture, the present state could be assessed as hazardous. They stated that, among methods of treatment known, that recommended offered the most likely promise of regaining adequate firmness in the support -ground-paint complex of the work. They also recorded that tests in limited areas suggested that removal of complex extraneous coatings (varnish, retouchings and repaint) carried no more than the usual risks. They therefore came to the formal conclusions that the treatment most likely to achieve a satisfactory bond between all the constituents of this picture and to prolong its existence to the maximum included as an integral part the removal of the present varnish film; and that the treatment proposed had been discussed and studied in detail and, with the usual safeguards was acceptable. The text of the committee's report is in the National Gallery's archives.
This report, dated 24 April 1967, was submitted to the Trustees at a meeting on the 4 May. They resolved that the treatment proposed by the Chief Restorer should be carried out.
Treatment carried out in 1967–1969
The limited amount of laying of loose paint which was possible on the upper surface of the painting with the old varnish layer ‘in situ’ was done, using gelatine dissolved in water (1 part by weight to 15 parts of water), the adhesive being kept warm at 30°C., and the loose paint flakes pressed back into place by means of a thermostatically-controlled, electrically-heated spatula. A hindrance to treatment was that whereas in most pictures detachment of the paint or ground layers from one another or from the support usually first manifests itself in the form of raised-up blisters, which can therefore be laid down before actual loss occurs, loose paint in the ‘Bacchus and Ariadne’ occurred mainly as thin flat flakes which it was difficult to locate before they were about to fall off, or indeed had fallen off. After the initial paint laying, varnish removal was proceeded with, and it was found that the most expedient method was to treat small areas of about 100cm2 at a time, carrying out cleaning and fixing of loose paint more or less simultaneously. The procedure was first to fix the paint down as much as possible then clean the varnish out of the natural age cracks in the paint since its presence inhibited the gelatine adhesive penetrating through the cracks to reinforce the gesso ground. Wax was not used to fix down the paint, because of the likelihood of its staining or darkening the absorbent gesso ground. Cleaning solvents chosen removed the actual varnish layers quite easily, but the action of the organic solvents in dissolving the resin varnish was halted at four separate stages by intermediate coats of greasy colouring material which it was easier to remove with a mild soap (a solution of sodium oleate, 1 part in 15 parts of water). The cleaning, in the sense of varnish removal was the least arduous and problematic part of the entire restoration. Many of the retouchings and the scumbled repaint in the sky could be removed with the varnish layers, the remainder being left for further attention at a later stage. After the varnish had been completely removed, the entire paint surface was faced with a layer of mulberry paper (a fine but strong, long-fibred tissue paper) using an adhesive of mastic in turpentine incorporating some wax, after which the picture could safely be laid face down for work to commence on the back. The old relining canvas, of which the adhesive was animal glue was removed quite easily by dry scraping of the glue layer. It could then at last be seen that the back of the original canvas was, as stated many years previously by Morrill, really covered with a thin but very compact, whitish coating. Analysis by chemical microscopy and gas-chromatography showed that it contained some lead white (basic lead carbonate) in a medium of drying oil (probably linseed) mixed with rosin and animal glue. The composition suggests an adhesive, probably the residue from some past relining, rather than paint in the protective or decorative sense. The results of analysis signified that any solvent or chemical reagent capable of removing it, would also be capable of attacking the original paint on the front of the picture, particularly in view of the thinness of the canvas and gesso ground and the disintegrated state of the latter. The method which had to be resorted to was scraping off the lead white layer, which though thin was very hard and tough, millimetre by millimetre with a small surgical scalpel. It was by far the most difficult and tedious part of the restoration and also very nerve-racking, especially since from time to time small holes in the original canvas were uncovered giving a glimpse of the reverse of the paint layers on the other side. The later stages were made easier by carrying out the scraping under a Zeiss foot-operated stereo-binocular 'Operation Microscope', (see Fig.4, p.6) then just acquired by the Conservation Department, and in fact designed for delicate surgical operations.
After removal of the lining canvas and old adhesive layer there was found to remain on the back of the original canvas a gesso ground, similar to that on the front but so thin as not to hide the fine canvas grain. An unexpected discovery was that of some drawings and inscriptions on the gesso on the back of the canvas. Being in black pigment, the drawings, which are rather faint, showed up well in infra-red photographs, one of which is illustrated in Fig.5. The quality of the drawings, seemingly done with the point of the brush, was such as to suggest that they were by studio assistants rather than by Titian himself. In the upper right corner of the back of the canvas was the upper part of a woman's body with part of a circle drawn round it and flanked by two profiles on a larger scale. In the upper left corner were diagrams and a further profile, somewhat resembling that in the bas-relief in Titian's ‘Portrait of a Lady’ (No.5385). At the base are inventory numbers: 'No.203 di Titiano', and again (larger) 'No.203'. This was the number allotted to the picture when it was in the Aldobrandini collection in the 17th century. The drawings and inscriptions had necessarily to be covered up again during the application of a new support to the painting, as described below, but were fully recorded in photographs.
After complete removal of the old adhesive layer the gesso ground which remained on the back of the picture was sized with a dilute solution of skin glue to prevent wax-resin adhesive from staining it. The careful laying of loose paint from the front of the picture subsequent to varnish removal was so successful that it was finally decided that lining with new canvas combined with wax-resin adhesive impregnation of both ground and paint film could be dispensed with. It was also considered that a rigid support might be preferable to lining canvas, having regard to the thinness of the original canvas and the history of the picture's condition. The canvas was therefore stuck down with a wax-resin adhesive onto a composite solid support consisting of two sheets of 'Sundeala' synthetic board sandwiching a honeycomb paper core. The construction provided a non-warping rigid support having solidity without excessive weight.
With the picture safely mounted on its new support and the surface cleaned free of all surplus adhesives, the remaining retouchings and repaints which had not come away during the varnish removal were tackled individually, either with suitable solvents or by gentle scraping.
Losses in the paint and ground were first filled with putty then inpainted to match surrounding original paint using modern non-fugitive pigments in a synthetic resin medium. The whole was then varnished with a thin coat of colourless synthetic varnish of fairly high gloss to compensate for the somewhat 'dry' or matt appearance of the paint surface.
The condition of the picture after cleaning and before retouching
As recounted in the Introduction above, consideration of whether or not the restoration, including cleaning, of the Titian ‘Bacchus and Ariadne’ should be carried out was a matter for detailed and long discussion on the part of the international committee, the National Gallery Trustees and members of the staff. Even after there was general acceptance of the fact that treatment would be in the best interests of the physical preservation of the painting, there was some heart-searching. The late Sir Martin Davies, who had replaced Sir Philip Hendy as Director in January 1968, described the dilemma very cogently as 'whether seeing without obfuscation what is preserved of this picture could be advantageous [. . .]', or 'that to see Titian's picture clearly in its present state would be disadvantageous, i.e. it is so much damaged that obfuscation is the means of conserving admiration' (note 19).
In the event, actual paint losses were rather fewer than had been anticipated from the X-radiographs. Some of the black patches in the radiographs which looked like lacunae in the paint on the front turned out to be losses in the lead white adhesive layer on the back of the original canvas and were probably the result of attempts to remove that layer in the past. There was, happily, very little wearing of the major part of the paint surface, apart from the sky on the left, as mentioned above. Fig.6 shows a black-and-white photograph taken after cleaning and before restoration illustrating the extent of loss and damage. Plate 3 (p.29) shows the head and arm of the Bacchante with the tambourine during and before retouching.
The picture after cleaning and restoration
Puttying and inpainting of paint losses presented no special difficulties, although the large number of small losses made it a painstaking and lengthy task, but nevertheless a satisfying one in the course of which the visual disturbance caused by so many small holes and damages were gradually suppressed, enabling once again the picture to be appreciated as a unified image. The gain in colour and clarity with cleaning was enormous. The effect can, to some extent at any rate, be appreciated by comparing the colour photograph of the picture uncleaned except for the preliminary test areas (Plate 4, p.30) with that of the picture after cleaning and restoration (Plate 5, p.30). Looking at the picture before cleaning it required the eye-of-faith to comprehend how Titian could have been considered the greatest colourist of all time. Now it is possible to admire again the skill with which he succeeded in harmonizing such strong and contrasting colours, scarlet and blue, orange and green, crimson and white, a skill so admired and commented on by critics of the past, but in more recent times lost from many of his pictures for probably several generations of viewers. No less astonishing are the newly-found subtleties of the primrose-yellow drapery beneath the urn in the left foreground (Plate 2, p.29), the delicate violet drapery of the Bacchante with the tambourine (Plate 3, p.29), and not least the great variety of flesh tones, from the pallor of Ariadne to the dark russet of the satyr with the snakes.
Of the many differences revealed by cleaning one of the most important has been the re-establishment of the effect of recession. The 19th century varnish, by blurring the transitions from blue to green in an all-over muddy tone, had had the effect of diminishing the distances within the picture. Before cleaning, the promontary above the head of the cheetahs looked near instead of about half a mile away as it now appears. The ground on which the procession moves can be seen to be rising to the right. The intensity of blue of the sky can be seen to vary, as it does in nature, being more intensely blue overhead. At the same time the faintly purplish (ultramarine) blue of the sky is now differentiated from the slightly greenish (azurite) blue of the distant landscape.
It may be concluded that although the primary aim of the restoration of 1967–1969 was to safeguard the physical survival of the painting, it conferred the added benefit of the rediscovery of Titian's masterpiece after more than a century of semi-oblivion.
Notes and references
1. Gould, C., ‘National Gallery Catalogues, The Sixteenth-Century Italian Schools’, Published by Order of the Trustees (London 1975), pp.268–74.
2. Gould, C., ‘Titian, Bacchus and Ariadne’, Published by Order of the Trustees, Publications Department, National Gallery (London 1969).