Santos Juanes de València
Since the creation of the Department of Restoration and Conservation of the Polytechnic University of Valencia, Palomino’s work in the church of Santos Juanes became a subject of study. Part of the murals – burned in 1936 – were torn off and later partially restored in the vault. Its state of conservation has not had a solution until now.
The conditions that this work brings together required a special intervention. The chromatic reintegration of the practically disappeared paintings – the preserved fragments account for 30% of the total – required an alternative approach.
Today, once the first phase of chromatic reintegration is finished, the work carried out – the technical and conceptual solution – has become a world reference. In the words of Guianluigi Colalucci, restorer of the Sistine Chapel, “what was achieved in Los Santos Juanes is a feat.”
There was historical graphic documentation. A black and white image taken by photographer J. Alcón before the fire.
The use of photography as a material for chromatic reintegration is justified by the fact that it is an objective approach to the original work. By not taking the character of the painting, it does not replace it, it does not falsify it.
But did the state of the art have the necessary resources to apply that image on the bare mortars that coexisted with the preserved fragments?
The answer was NO.
This is the summary of the work carried out, especially since Arsus Paper acquires the commitment to solve the technical challenge represented by transferring a photographic image to the irregular surface and volume of the vault, respecting the necessary permeability of the mortars. Taking into account, at the same time, the requirements demanded in any mural painting restoration project.
The object of all the efforts of those involved was simple, in the words of José Luis Regidor -one of those responsible for the project- “it is about trying to return to this work, part of the appearance that made it beautiful.”
The approach designed by the project management team, and which has laid the foundations of the system, can be summarized in these sections:
Consolidation and restoration of the preserved fragments.
– Rectification, straightening and scaling of historical photography.
– Color management. Photography and its treatment with HP Artist software.
– Color for the image in B / W.
Printing and transfer of the image to the wall support.
– Papelgel system
Polytechnic University of Valencia
Department of Restoration and Conservation of Cultural Assets
Approach to the intervention
Restoration of paintings
Treatment of the historical image
PICTORIAN RESTORATION OF PALOMINO MURALS
IN THE CHURCH OF SANTOS JUANES DE VALENCIA.
-Consolidation and restoration of the preserved fragments.
The definitive support. The pictorial plaster.
The principle of “similarity with the original” that governs the selection of materials to be used in restoration as a guarantee of compatibility (physical and aesthetic) and safety is the one that has been followed when making the wall filling that the image was to receive transferred. This criterion of making the nature of the final support prevail (traditional wall plaster) over the transfer system has been a challenge for the project.
first transfer tests in the arch
For the selection of the final support, receptor of the transfer, the common pictorial plasters or filler mortars for traditional mural pictorial reintegration were studied; that is, lime and sand mortars, plasters, etc.
The ideal plaster simply had to consist of a mortar as similar in shape and form to that used by Palomino for the execution of his work; that is to say, a mortar of lime and sand. According to the analyzes carried out, this plaster would be composed of lime and marble dust in a proportion of 1/1 and 1/2 and a maximum granulometry of 0.6 – 0.7.
After the evaluation and study of different proportions and variables, we worked with a mortar of air lime and quartzite in 1/3 proportion with a small addition of a resin in a reticular form that improved the reception of the ink transfer.
Treatment of images.
Rectified, straightened and scaled up of historical photography.
The photograph by J. Alcón captures a concrete view of the three-dimensional space of the Los Santos Juanes vault. The image is made up of various factors such as the optics used, the location of the camera, the architectural shape of the vault, etc. It was necessary to study and interpret all this to be able to unfold it to a plane.
Georeferencing software is used to locate an image in space. Basically it is about matching selected and recognizable points taken in the vault (which in this case would be representative points present in the painting) with the corresponding ones in the photograph.
Once the data is collected (the control points of the vault were collected with a surveying station), they are entered into the program – the Microestation was chosen as it is a software that introduces a sub-program with which it is possible to carry out both georeferencing and remote sensing tasks called IRAS_C-. The processing reconstructs the image to fit the control points, elastically modifying the position and coordinates that the pixels occupy.
vault and intervention area
scan of the interior of the church
IRAS_C georeferencing software
Color management. Photographic capture and treatment with HP Artist software.
The Hewlett-Packard company has developed a tool created specifically for the control and adjustment of color in the digital reproduction of works of art, the Artist program. When the restoration work began, the software was still in the testing phase. Technicians from the R&D department of HP’s Large Format Division in Barcelona would process the photographs of Palomino’s pictorial set.
The Artist system takes the work and uncertainty out of making manual color corrections.
The integration of system components such as cameras, lighting, and printers, reduces the time required to produce high-quality, accurate jobs. There is no need to regularly illuminate the artwork or correct the color, the software automatically fixes such problems during processing. The software performs automatic white balance, corrects for lighting uniformity, performs color corrections, and generates a TIFF file with a built-in ICC profile that is specific to that particular artwork.
Color for the B / W image. Digital coloring.
The fragment corresponding to the work area of the B / W photograph by J. Alcón is enlarged, already corrected, to the actual size that the Palomino frescoes present in the vault, approximately 250 square meters.
Indeed, the enormous magnification makes the silver halide particles that make up the photographic image visible, making the image dull up close. But the pictorial set will be observed from the floor of the temple, 26 meters away, which will reduce, in turn, the proportion of what is observed.
To add color to J. Alcón’s image, the photographic sweep treated with the Artis software is first superimposed on it.
After the two images have been adjusted, the areas of the color photo that have no paint are selected and removed. In this way, two superimposed layers are obtained, ready for the digital coloring phase (PhotoShop program).
The color layer is desaturated to be able to equalize and level the lights and shadows in J. Alcón’s photograph, adjusting the gray scales of the original photograph in B / W, with respect to those of the color photographic sweep.
Taking as a reference the colors of the original painting, transparent chromatic layers are created – as glazes of color – until the grays are toned.
Finally, the result obtained is readjusted, increasing the level of detail so that the pieces fit together as much as possible.
assembly of the original fragments and photo in B / W
application of color to the photo in B / W
final appearance of the transferred image
-Printing and transfer of the image to the wall support.
The technical challenge: transfer only the ink that constitutes the image so as not to waterproof the wall.
The most important reason, apart from the convenience of the wall to transpire (balance indoor / outdoor humidity and avoid condensation) and remain healthy, is that in the case of possible leaks, they will inevitably drag salts and the only way they would have is precisely the surface of the preserved fragments of the Palomino frescoes.
The current state of the art offers (with greater or lesser success) different solutions for transferring printed images, but until now none responded to the different needs that a mural work requires – especially and as has been explained – to preserve the permeability of the support.
The Papelgel system.
Arsus Paper has developed a temporary support for transferring inkjet prints. Starting from the original Papelgel® product, the new development provides better control of the elasticity of the material. On the other hand, the new composition of its solid-gel structure allows transferring only the ink from the printed photographic images to all types of surfaces, regardless of their texture, shape and porosity, without the need for special preparations of the support.
- -It is printed with photographic quality pigmented inks.
- -It is transparent, the monitoring of the work is complete.
- -It is elastic, which allows it to be adapted to the textures of the plaster, to the irregularities of the volume of the surface, as well as to adjust the possible dimensional defects of the image to be transferred and to ensure a correct fit.
- -Ink transfer does not require any adhesive; that is, it only transfers the ink without waterproofing the wall support.
- -The transfer is carried out with water, excluding harmful solvents both for the original work and for the operators.
- -The transfer does not reduce compatibility between the ink and the lime plaster.
Transfer system with the new development of Papelgel:
printing on Papelgel
bath in water
presentation on the wall
appearance of the work area
After the transfer process on the wall surface, only the ink remains, and its compatibility with the final support will determine the stability and safety of the print.
detail of a fragment
The workshop for the analysis and intervention of mural painting of the Institute for the Restoration of Heritage of Valencia (IRP) carries out a meticulous study on the behavior of pigmented ink transferred on mural plaster. This is a summary of the tasks carried out:
INVESTIGATION AND EXPERIMENTAL DEVELOPMENT OF THE BEHAVIOR OF INKJET INKS ON LIME MORTARS AND OTHER PICTORIAL SURFACES.
Different studies support the stability of inkjet prints with pigmented inks on various supports, but there is no evidence of their behavior on lime mortars, since the application is unprecedented in the world.
The Papelgel transfer system requires that the originally liquid ink dry (solidify) on the temporary support, be dissolved again and be permanently fixed on the wall surface. This change of state or the fact that the wall surface of lime and sand maintains a strongly alkaline PH (13) for a long time, are factors that could alter the stability of the whole. To resolve these doubts, studies were carried out to confirm the suitability of the pigment ink / wall plaster structure.
A large number of specimens were subjected to cycles of accelerated artificial wear (UV lighting, temperature, humidity and contaminated atmospheres) and both the comparative chemical analyzes and the evaluation of changes in color difference (DE *) and gloss gave satisfactory results, finding for example, more weakness in the wall support than in the inks in the case of the contaminated atmosphere test.
On the other hand, comparative tests of resistance to abrasion were carried out, which allowed evaluating how the structure reacts to factors such as erosion, friction, etc. It was possible to conclude that transfers in general have a moderate resistance to abrasion compared to a pictorial surface made in fresco, but very similar even superior to surfaces made dry with watercolor, which is the most used medium in restoration.
From the chemical resistance tests it was found that the transfers are sensitive to high polarity solvents such as toluene, and to a lesser extent to water.
The oldest specimens (2 years) have greater chemical resistance than the most recent ones (3 months); that is, due to the gradual setting of the lime mortar, as well as the curing of the binders in the inks, the chemical resistance of the transfers increases over time.
Contact sponge absorption tests were also carried out to objectively confirm that the transferred ink does not constitute a barrier to the natural perspiration of the lime and sand plaster.
The contact sponge methodology -developed by the CNR-ICVBC of Florence- has been proposed as a simple and quick method to assess “in situ” the effectiveness of a water-repellent treatment on stone surfaces.
The method is based on weight differences according to the formula:
Wa (g / cm2. Min) = (Pi-Pf) /23.76 x t
Where (Wa) is the amount of water absorbed during the test.