Untitled painting by Giorgio Preca

Challenges in Conservation

Heritage Malta recently held an exhibition entitled ‘Giorgio Preca (1909–1984) ta’ Malta: An International Artist with a Modern Spirit’ at the National Museum of Art, MUŻA. Giorgio Preca was a Maltese artist who was mostly active post World War II. While he made use of traditional painting materials and their application, his true novelty lay in his ability to detach himself from the long-established tradition of realism, which was still predominant in the Maltese art scene at the time. Preca’s ingenuity could have been a consequence of his experience outside of Maltese shores, awakening his interest in the art movements emerging on the Continent. Consequently, his technique was clearly inspired by various spheres of Modern Art, amongst which were Cubism, Expressionism and also Abstraction. Moreover, while Preca often depicted realistic scenes, such as still lives and landscapes, the artist also delved into the imaginative realm, representing aliens and dragons. The former series depicted the artist’s own fictitious narrative revolving around alien creatures from outer space that landed in Malta. A large yellow abstract painting, Untitled, by Giorgio Preca, reflects the artist’s interest in depicting alien species. This work represents various geometric shapes, such as zig-zag lines and ovals, set against a bright yellow background. The painting was produced in 1953 by Giorgio Preca, as is confirmed by a signature and date inscribed at the painting’s bottom left. It has an identical size and format to that of Preca’s work entitled Aliens from Outer Space on the Isle, which is dated to 1956. Hence, the two artworks might have originally formed part of the same series of paintings.

In preparation for the exhibition, twentyfour modern works by the artist Giorgio Preca were conserved and restored at the Paintings’ Conservation Department within

Heritage Malta. Modern artworks often tend to be more challenging to conserve and restore than artworks executed prior to the nineteenth century. This is because Modern and Contemporary artists often deviated from the use of traditional materials and techniques established by the Old Masters in order to ensure the durability of artworks.

Manufacturing technique, state of conservation and past interventions

Upon close inspection, conservators at Heritage Malta noted that Preca’s Untitled yellow abstract was most probably composed of modern oil paint on canvas. The paint was applied onto a single large section of canvas, measuring 91.3 x 365.7 cms. Since the yellow depiction continued onto the painting’s turnover edge (tacking margins),1 the artist may have completed the work prior to mounting the canvas onto its stretcher frame. In comparison to other works by Preca, the paint of the yellow abstract was applied in an even and fine manner, while also featuring the application of bright and vibrant tones. It, however, lacked the very prominent use of impasto, which was evident in other works by the artist, many of which were featured in the exhibition.

Moreover, the painting depicts a lack of colour saturation and light reflectiveness, the factors of which may indicate the entire lack of a varnish, or the presence of a very thin varnish application that was absorbed by the painting’s constituent materials. The painting’s reverse showed signs of dust and grime deposited throughout the years. It also depicted the presence of mould spores.

Furthermore, the artwork’s canvas featured numerous deformations which evidently conditioned the structural stability of the painting. Said structural issues could have been a result of various environmental causes including fluctuations in relative humidity. The deformations present would have been further aggravated by the fact that the painting lost its tautness over the years, and this slack led to it deforming in several areas. These distortions were particularly noted upon illuminating the painting perpendicularly from one side. These structural deformations would have also formed as a consequence of the presence of multiple tears and punctures which threatened the object’s stability. Moreover, tears which are left untreated over the years often become progressively distorted. The punctures noted were rather large and were found in various areas of the painting, ranging from its main areas to one of its tacking folds. Most tears were identified along the weft direction, since these yarns are straighter and weaker, whereas the warp threads are typically highly crimped, thereby being stronger.2

A preventive intervention which was aimed at stabilising such punctures was undertaken in the past, during which rectangular paper patches were applied to the back of the tears. On the other hand, a white rigid material was used in order to fill the losses at the painting’s front. These fills were probably applied while the artwork was upright as the white material is also visible in various drippings seen over the paint layer. During this intervention, restorations or re-integrations in the form of retouchings were not applied to the artwork. Moreover, Preca’s bright colours were concealed beneath significant soiling, making the artwork appear darker and less saturated. The artwork also absorbed unknown substances, which caused numerous evident stains and drip marks to appear on the painting’s front. Apart from soiling and stains, the paint layer also suffered various cracks, including stretcher bar cracks, which were resultant from the edges of the stretcher and its cross bars imprinting onto the paint layer.

Conservation and restoration interventions

The painting’s front and back were both documented by means of photography under diffused and raking light, as well as under ultraviolet illumination, prior to undertaking any interventions, and all findings were compiled in a conservation report. This process was imperative in order to identify the artefact’s condition at closer range, to document its state prior to any interventions undertaken, and to identify any treatments which the object may have been subjected to in the past.

The back of the canvas was primarily cleaned using dry methods. The mould was then removed using a brush and a backpack vacuum cleaner having a HEPA filter, which ensured that the spores were trapped and could not be spread. The canvas was further cleaned from dust and grime using a sponge specifically manufactured for conservation. Following the cleaning of the primary support, paper patches which were adhered to the various tears during a previous intervention were removed. Upon the removal of the paper patches, five tears were made evident, three of which were closed, and two of which were open, the latter manifesting losses in the canvas support. The deformations in the canvas support were primarily treated using moisture, heat and pressure applied to the painting’s reverse. This intervention reduced distortions and facilitated the eventual re-alignment of the threads, thereby allowing for tear repair.

Following the reduction of deformations, tears were re-adhered. This was undertaken by aligning individual linen yarns perpendicularly to the tear’s direction. The yarns were aligned with the canvas’s original threads and were varied in length, in order to re-distribute the concentrated strain that originally resulted in the fracture.3 They were applied using very small amounts of a compatible and stable adhesive, reinforcing the tears, and preventing them from re-opening in the future.

Losses of canvas were then inlayed. This process involved using pieces of linen canvas with a similar weave count as that of the original, cut to the shape of the losses. These were then placed to fill each loss and adhered using a stable adhesive having an appropriate bond strength. These inlays were then further secured with individual yarns.

The painting’s border at the upper right edge was particularly slack and weak, while also revealing a tear along the fold. This area required significant strength in order to carry the load of such a large painting, which is often held at the edges. The application of strips of canvas to the effected margins, in a method known as partial strip lining, was identified as the ideal technique to stabilise the painting’s right edge. In preparation for strip lining, the nails attaching the painting to the stretcher were removed at the top right, right, and bottom right sections of the painting, in order to expose the tacking margins and the tear noted.

The tear in this area was first reinforced using thin non-woven polyester. The right tacking margin or border was then stabilised further through the application of strips of linen canvas using a hydrophobic, strong, loadbearing and re-treatable adhesive. On their inner extremities, the canvas strips were frayed and feathered, in order to avoid the imprint of their edges onto the front of the painting, due to discontinuities in plane. The feathered edges were placed past the tacking margins in order to gradually and evenly distribute the load. The latter linen strips also permitted conservators to re-stretch the loose painting, securing it back onto its wooden frame.

Since the stretcher’s wooden keys were either missing or damaged at some point in the past, all remaining keys were removed and expandable bolts at the stretcher frame’s joinery were installed. Each bolt was attached to each of the corners, and to alternating sides of the cross bars. The bolts were then secured in order to ensure that the painting was taut on the stretcher frame.

The front of the painting required the removal of soiling and the reduction in the visibility of stains apparent on the painted surface. Therefore, the painting’s cleaning was conducted in three distinct phases. During the first phase, dry methods - including the use of sponges designed specifically for conservation - were used.This allowed for the removal of the upper-most layer of dust. This intervention was followed by two other phases of cleaning, which were undertaken using water-based treatments.

Recent research has suggested that a solution targeting the soiling would be one having the same scientific parameters as those of the painting’s surface.4 Therefore, the artwork’s pH and conductivity were primarily measured using scientific meters. Small amounts of chemicals were then added to pure water to form a solution with the same pH and conductivity values as those of the painting’s surface. This tailor-made water solution was applied gradually and carefully to the paint layer to further clean the soiling upon its surface. This intervention was successful in uncovering the artwork’s original bright and vibrant colours.

While improving the painting’s aesthetics, this cleaning intervention also helped in preserving the artwork by reducing the risk of rapid chemical and biological deterioration.

Although a significant amount of soiling was removed using this method, a few stains and drip marks still remained visible. Additional tests revealed that it was possible to perform a deeper cleaning with the use of tailor-made aqueous gels. These gels were applied locally onto the remaining stains and were cleared in order to eliminate residues from the surface. This method was successful in leaching and removing the foreign material that was trapped within the original paint layer.

Following the various conservation treatments applied to the yellow abstract painting by Giorgio Preca, conservators proceeded to undertake the visual and structural re-integration of paint lacunae. The re-integration primarily consisted of applying a filler to the paint losses, which was then levelled down to the painted surface. Additional filling material was then applied with a fine brush in order to imitate the painting’s texture.

Finally, retouching was carried out using a stable and reversible varnish-based paint medium. The latter restoration treatment was primarily intended to reduce the visual impact of paint losses suffered in the past. The retouching was applied using fine dots in various colours, built up to match the tonal qualities of the corresponding areas. This technique was utilised in order to ensure that viewers would be capable of distinguishing the retouched areas from the original when observed from a very close distance. The latter retouching methodology follows international ethical standards in conservation and restoration. The painting was not coated with a final varnish layer in order to respect the artist’s wish to retain the painting’s unsaturated tones.

Conclusion

In conclusion, Modern artworks such as Preca’s Untitled yellow abstract, often give rise to various new challenges for conservators. This was particularly noticeable in the cleaning of the artwork’s paint layer from soiling and evident stains. The paint was applied less than one hundred years ago and was thereby not yet fully cured, making it sensitive to various cleaning agents. The painting’s cleaning, as well as various other techniques utilised in this conservation-restoration project, were presented to the public through various videos, bringing further light onto the importance, interest and beauty of the conservation of such Modern artworks.

Notes and References

1 Tacking margins refer to the far edges of an artwork, where the canvas is not normally painted. These are usually folded over the sides of a painting’s stretcher frame.

2 HACKNEY, S., 2020, On Canvas: Preserving the Structure of Paintings, Getty Publications, Los Angeles, p.202. During the formation of textiles, the warp yarns are longitudinally stretched on a loom before the weft yarns are interlaced by means of passing them through the warp yarns in a horizontal direction.

3 Each yarn applied was frayed on both ends in order to ensure that its sharp edges would not cause deformations at the front of the painting in the future.

4 CREMONESI, P., 2020, The Aqueous Environment for Treating Polychrome Works of Art, De Kunstkliniek Veer & Veer, Hilversum, p. 98.

Bibliography

MICALLEF, K. & VELLA, G., 2021, Giorgio Preca ta’ Malta 1909-1984: An International Artist with a Modern Spirit, Heritage Malta Publishing, Malta

CREMONESI, P., 2020, The Aqueous Environment for Treating Polychrome Works of Art, De Kunstkliniek Veer & Veer, Hilversum

STONER, J.H. and RUSHFIELD, R., 2012, Conservation of Easel Paintings, Routledge, London

YOUNG, C., ‘Accelerated Ageing of Fabric Supports: Is It Possible?’ in Scientific Analysis of Ancient and Historic Textiles: Informing Preservation, Display and Interpretation; Postprints, edited by Rob Janaway and Paul Wyeth, Archetype, London, pp. 111-117

HACKNEY, S., 2020, On Canvas: Preserving the Structure of Paintings, Getty Publications, Los Angeles

In 1961 several earthenware amphorae were recovered from Xlendi Bay in Gozo. Others were taken up during the subsequent years, regrettably, sometimes illegally. These amphorae eventually formed part of the Heritage Malta National Collection at the Gozo Archaeology Museum in Victoria, Gozo. The best preserved were displayed at the museum whilst the rest – a total of 39 amphorae – are stored.1

As preparations were underway for the setup of the new Gozo Museum, from the end of 2020, these stored amphorae were gradually brought over to the Heritage Malta Objects Department laboratories in Bighi. Their conservation was ready by mid-2022. Although the great majority of the project consisted of amphorae, there were also a few other ceramic artefacts with some agricultural tools and related objects. Following conservation, some of the objects will possibly be also exhibited whilst the rest will be put in storage.

Initially each amphora was unpacked, documented photographically and its state of preservation was also recorded. This information shed light on what treatment was necessary for each amphora. Communications with the curator was also vital to understand the context of these amphorae and their historical background. Discussing the nature of the biotic crust present was also done with HM’s inhouse biologist.2

Types of amphorae

The amphorae which were conserved are of two types: the transport amphora type - large with a pointed base to facilitate carrying on the shoulder and easily stackable - and the table amphorae type - smaller than the latter, with a flat base, used to serve food and drink. Both vessels were meant to hold food related products, namely wine and oil (correspondence with Mr George Azzopardi).3 Where desalination of the amphorae was deemed necessary, the facilities at the Underwater Department of Heritage Malta were used.

State of preservation

The state of preservation of these amphorae was dominated by their prolonged presence in the underwater environment. The complex chemical, physical and biological aspects of the underwater environment and their interaction with these objects was of great significance. The condition of these amphorae also depended on a wide range of factors intrinsic to the amphorae, such as: the nature of the ceramic fabric and the firing temperatures used. Furthermore, the drastic change in environmental conditions from a marine to a terrestrial one have undoubtedly left an impact on their state of preservation. This is especially relevant as some of them had been recovered illegally and so it is understood that measures to minimize the environmental shock were not necessarily taken or done appropriately. Although the state of preservation differed from one amphora to another, in general the amphorae had deposited surface accretions,4 and biological crusts5. The amphorae were also covered with a layer of dust resulting from their storage environment.

Some of the surface accretions were thick and intense on some amphorae while thin and sparse on others. It was also commonly noted that some amphorae had very thick concretions in certain parts, most notably filling the hollow parts of handles and below the rims, whilst very little or no concretions at all on other parts such as on the body. The presence of these accretions is likely to be related to the orientation of the vessel when it was laying on the seabed. In fact, amphora which were broken underwater may display different patterns of surface accretions.

Where the ceramic fabric was progressively very friable and powdery, the hard accretions broke down due to their loss of adhesion to the surface, exposing a deteriorated surface.

Some fouling organisms, or plants and animals which lived in contact with a manmade object (Pearson 1987:14) were found on many of the amphorae. These included various sizes of tubes worms which leave a calcareous tube around their body and adhered firmly to objects such as the amphorae.

A biotic crust was also observed on most amphorae. This commonly consists of a wide range of biological organisms such as different algae, sponges, and bacteria. Although after excavation and surfacing these organisms will stop growing, whilst underwater they form part of a complex ecosystem (Pearson 1987:13,14).

The most common form of damage observed on these amphorae is through impact which resulted in either breakage and/or formation of cracks. This could have happened either during the shipwreck, or due to the movement of the amphorae whilst on site, when they were taken out from the water, during transport or spontaneously from salt damage. The erosion and the presence of accretions on the edges is indicative of where damage happened underwater or not. In the case of breakages, most cases although not all, fragments of a broken amphora were brought for conservation and are likely to have been lost or possibly disintegrated with salt damage. The formation of cracks from impact were found to be either hairline cracks (minor cracks) or fractures (cracks which cross completely from one side to the other of the amphora). Hairline cracks are mostly stable whilst some fractures tend to be unstable.

Several amphorae appeared to be in a stable condition, however others manifested damages related to soluble salts, mostly chlorides of sodium and magnesium. These chlorides are a major chemical constituent of seawater (Pearson 1987:3). Such damages are easily explained due the prolonged immersion in seawater and the porosity of earthenware making the fabric contaminated with seawater (Buys and Oakley 1993: 23, Pearson 1987: 3,113). Whilst in solution such salts are not damaging, when the amphorae have been excavated from underwater and left exposed to dry, damage occurred. When the water constituent of the solution evaporates, as a result, salt crystallisation occurs. Salt efflorescence is visible as loose white salt deposits on the surface. The formation of crystals occupies a greater volume than the solution, thus causing damage to the earthenware fabric. The crystallisation of salts causes deterioration factors, such as spontaneous breakages, crumbling, and friable surfaces.

In some cases, sub-efflorescence was also noted whereby efflorescence of salts happened under the ceramic surface. In this case, the salts become visible on newly exposed surfaces. As sub-efflorescence continues it results in scaling of the fabric.

Staining was noted on a few amphorae. Iron staining is related to their proximity to iron, possibly iron supports. Another type of staining could be a result of the original use of these amphorae, that to carry liquids such as oil and wine. Earthenware, being a very porous material, would have absorbed such materials, resulting in staining and contributing towards chemical deterioration.

Conservation treatment

After assessing the condition of each amphora, the proposed conservation treatment was discussed with various other conservators and senior conservators regarding the best way forward to conserve each amphora.

The first step was to clean the amphorae by dusting the surfaces with a soft brush to remove loose surface dirt. Cleaning of engrained dirt was carried out using brushes and cotton wool swabs with deionised water. With whole and intact amphorae, only the external surfaces were cleaned, so as not to hinder any possible analyses being carried out in the future.

Marine concretions were not removed as the amphorae were not completely encased in concretions and thus the original ceramic surface was not completely disfigured. The concretions were also evidence of the marine environment which the amphorae were part of after the shipwreck and thus part of their history. Although laden with soluble salts, removing the concretions might cause damage to the ceramic itself. Being calcium based, the concretions might be harder than the ceramic fabric, so removing them would require the exertion of physical stresses which the ceramic might not withstand. It could also be difficult to remove such concretions due to the possibility of them to have penetrated into the ceramic body.

Desalination by immersion was carried out on 6 amphorae, as the problem of soluble salts was pertinent. These amphorae were first dusted with a soft brush. Where the surfaces of the amphorae were very friable, preconsolidation of the fabric was carried out before desalination.

This was done by applying 2% Paraloid B72 in acetone (w/v) by brush or by immersion for very small pieces. This process was repeated for very deteriorated pieces as was necessary. The pieces were placed in large tanks which were filled slowly with deionised water allowing for air in the body to escape slowly. Daily readings of conductivity were taken until constant readings were achieved. When this happened, the water was changed and readings were continued to be taken. Once readings were sufficiently low, desalination was stopped, and the gradual drying process was started until the pieces were completely dry. The very friable amphorae were consolidated again after desalination.

Hairline cracks were consolidated with 2% Paraloid B72 in acetone (w/v). Wider unstable cracks were consolidated with 15% Paraloid B72.

The amphorae which had broken parts were then bonded in place. However, initially a trial assembly was carried out to determine the position of each piece. Without this crucial step, it could be difficult to find the place of certain pieces and thus this trial provided a guide on the order of bonding the pieces. These were held temporarily using strips of masking tape, clamps, bandages, cushions made from bubble wrap and buckets. The use of these materials depended on the shape, size, fragility of the body, as well as the presence of concretions. During this process, the pieces were numbered and then dismantled. Any amendments were done as required and the process was then repeated, this time with adhesive applied on the edges. Achieving a good alignment was difficult on a particular amphora with eroded surfaces and edges, which as a result left small gaps following reconstruction.

When choosing the most adequate adhesive, various criteria were considered. Firstly, the environment the amphorae will be exposed to (both in storage and exhibition), reversibility, glass transition temperature (Tg

- the temperature at which an amorphous polymer changes from being hard to a rubbery state [Horie 2010: 430]), aging, and practicality. Taking these criteria into account, Paraloid was used. This is a thermoplastic acrylic resin which is widely used in the field of conservation. Initially, the edges were primed with 5% Paraloid B72 (w/v) due to its superior aging properties when compared to Paraloid B44. Parlaoid B72 was applied by brush. After drying, 40% Paraloid B44 in acetone (w/v) was applied by brush or from a tube. Paraloid B44 was opted for because of its higher Tg when compared to B72 (Buys and Oakley 1993: 189, 190). After drying, excessive adhesive was cleaned off with a scalpel and by swabbing with acetone.

Conclusion

The conservation of these amphorae was a diverse project because each amphora had its individual requirements, as well as some challenges. Being large and heavy artefacts, extra measures were taken to support the pieces during the interventions, especially when it came to bonding. For packing, sturdy boxes were used with adequate cushioning to ensure safe transit to Gozo. From the 39 amphorae, one was found to be particularly challenging because of its advanced deteriorated state, large size and weight. This had to be handled with extreme care. Bonding the sherds of this amphora was a laborious task because the eroded edges made alignment difficult.

Despite the difficulties encountered, these amphorae were conserved following ethical principles of conservation. The processes of cleaning, consolidation, desalination, and adhesion were carried out to preserve these artefacts and allow them to be appreciated by the general public. Ensuring the long-term preservation of these amphorae requires a preventive conservation approach focused on providing environmental controlled conditions, a clean environment and minimal handling.

Notes and References

1 Personal communication with George Azzopardi, Principal Curator of Phoenician, Roman and Medieval at Heritage Malta sites, August 25, 2022.

2 Personal communication with Stephanie Sammut, biologist and curator at Heritage Malta, July 22, 2022.

3 Personal communication with George Azzopardi, August 25, 2022.

4 Deposited surface accretions is a general term referring to the deposited material on the exterior surface or inside an object. They are of various chemical nature, that is either silica based or calcium carbonate based. The chemical nature of the accretions is determined by the surrounding microenvironment especially pH and water temperatures (Pearson 1987: 12 and 13).

5 Biological or biotic crusts refers to the presence of a variety of living organisms on the exterior surface or inside an object (Pearson 1987: 14).

Bibliography

BUYS, S., and OAKLEY, V., 1993, Conservation and Restoration of Ceramics. Butterworth Heinemann: Oxford

HORIE, V., 2010, Materials for Conservation: Organic Consolidants, Adhesives and Coatings. Butterworth Heinemann: Routledge London and New York

PEARSON, C., 1987, Conservation of Marine Archaeological Objects, Butterworths: London

...after being painstakingly pieced and bonded together following treatment