Stained glass
workshop
Isabelle Baudoin

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Conservation-Restoration - public sector

Preamble :

Stained-glass has a special role in the public imagination. Mysterious, vibrant, fascinating, impressive in its monumental configuration and yet inherently fragile, the French “stained-glass heritage” is rightfully loved and admired even if all its dimensions (more specifically religious and aesthetic) are complicated and inadequately explained in the works.

For the same reasons conservator specialized in stained-glass is a fascinating job. All the encounters made on field express an unanimous opinion: “What a wonderful and meticulous job …”. Paradoxically a veil of incomprehension surrounds this spontaneous comment because the public ignores the truth about this profession that is usually imagined as romantic, strictly artisanal, quiet and escaping from all kind of economic conflict.

I would like, though this website, to share my passion for a profession and a sublime heritage but also to give an image of this profession at the start of this new century. This website will show the filiation with the traditional art profession - Nivard de Chassepierre, glass artist depicted by Bernard Tirtiaux in “Le Passeur de Lumière”, is without a doubt a brother - but today this stained glass artist job offers several distinctive facets. Creation involves contemporary concepts and new glass technologies; restoration involves professionals who work in the shadow of the original artists. They avoid changing and revisiting the works of art entrusted to them.

I would like to thank those who have enlightened and still illuminate my professional life: my birth relatives, my closest friends and the people who are truly passionate for stained glass. At the beginning of my career I had the chance to meet, Marie Berducou, Michel Petit, Françoise Perrot, Anne and Guy Le Chevallier, Jean-Marie Braguy, Marie-Françoise Dromigny, Gérard Degusseau, Jacky Vivien, Jeannette Weiss-Gruber, Isabelle Pallot-Frossard, George Brunel, Yves Gagneux, Daniel Imbert...to name just a few of them. And just as importantly all the workers who have worked on various projects, they will recognize themselves.

 

The profession of stained-glass Conservator-Restorer and it’s ethical rules

“The objects, buildings and environments to which society attributes particular aesthetic, artistic, documentary, environmental, historic, scientific, social, or spiritual values are commonly designated "Cultural Heritage" and constitute a material and cultural patrimony to be passed on to coming generations.Since it is entrusted to the care of the Conservator-Restorer by society, s/he has a responsibility not only to the cultural heritage itself, but also to the owner or legal guardian, the originator or creator, the public, and to posterity. The following conditions serve to safeguard all cultural heritage regardless of its owner, age, state of completeness or value.”

(Preamble of the Professional Rules of the E.C.C.O European Confederation of Conservator-Restorers Organizations)

In order to define as clearly as possible toward what our Conservation-Restoration of the cultural heritage tasks strive, it is important to increase public awareness of the deontological principles underlying our works. To this end, reminding the fundamental missions of the Conservator-Restorer defined by the E.C.C.O is not a luxury.

The stained-glass Conservator-Restorer is a professional who has the training, the knowledge, the skills and the experience necessary to act to preserve stained-glass for both the current and future generations ‘good. He can also help understanding them through respect for their aesthetic and historical meaning and also their physical integrity.

The main steps that are outlined below spell out the essence of his mission: diagnostic examaniation, preventive and curative conservation, restoration and documentation. We are going to illustrate every single step with chosen examples among the restorations conducted in our workshop.

>> The diagnostic examination consist in finding the constituent material, defining the conservation status of the stained-glass, identifying the changings, their nature and their scope, evaluating the causes of their degradations, determining the type and the extent of the interventions needed to preserve it. It includes a study of the documentation relating to that stained-glass. This chapter is developed in “Preliminary studies - public sector”

Example: emphasis of a phenomenon of condensation of the inner side of the stained-glass. The condensation is responsible for the frequent corrosion processes of the inner side of the glass and the weakening of the paint on this side.

Example of a medieval palmette altered on both sides.

From the left to the right, it’s the same piece seen on the inner face in transmitted light then reflected light and seen on the outer face in reflected light. The glass, according to its composition, is more or less sensitive to the action of both meteoric and condensation water. The action of the water dissolves some of its constitutive elements which in contact with the air and its pollutants cause corrosion. This corrosion may take different forms: it can reach the whole area as you can see in the inner face, or affect only certain areas in the form of small craters like on this outer face.

Example of the tampering of the glass and of the brown grayness on this view of the inner face of this medieval coin in reflected light. The glass paints used for stained-glass have a composition similar to glass and have the same reactions to water than the glass on which they are placed.

The nature and the form of corrosion may vary and would have different aesthetic impacts on the stained-glass visibility. In general, there is a loss of transparency more or less pronounced.

Glasses, paints, lead, all the constitutive elements of a stained-glass age and suffer from the impact of the constraints imposed by the damaging conditions in which they are placed. The leads become fragile, brittle and deform. The glass breaks easily and it is common to see in our churches wind, water or birds sometimes disappearing into the gaping holes in the stained-glass. The metal frames that support this stained-glass do not escape aging and they require regular monitoring and maintenance


>> Preventive conservation
consists in acting indirectly on the stained-glass, in order to delay its deterioration or to prevent the risks of spoilage by creating optimal preservation conditions compatible with its social use. Preventive conservation is also practiced when handling, using, transporting, packaging, storing and exhibiting the stained glass.

The main preventive measure used in the conservation of stained-glasses is the double-glass protection which is to put an outer protective glazing on a second metal frame placed next to the old stained glass. Thus it is isolated from atmospheric attacks, and thanks to a natural ventilation in the space between the two glasses condensation phenomena is significantly reduced. This method can be declined in several techniques and is now widely used in Europe.


>> Curative conservation is mainly to intervene directly on the stained-glass in order to delay the altering.

To do this, it is frequently necessary to remove the stained-glass to restore all the panels composing a bay or only parts of it in the workshop.

   

                

Removing the stained-glass from the metallic structure is a very delicate task, as the glass needs to be protected from further damage. Regarding the production of the sealing agent surrounding the panels, the work will be more or less long and difficult. Then the panels are correctly stored and brought in the workshop. Every single decision involving detachment has to be clearly substantiated because it is a major event in the stained-glass’ life.

The cleaning is one of the curative interventions, it is without a doubt the most complex and risky one since it is irreversible. It consists in eliminating from both faces of the glass the substances harmful to its conservation without tampering the painted patterns.

We systematically lead cleaning tests in order to define the most appropriates measures for the different issues. You will find here an example of a test on an outer face of a glass that has been considerably darkened by the corrosion products that have invaded the whole area (view under reflected light).

The cleaning allows us to discover beneath impressive layers of dirt the beauty of the original painting, it is clear of the harmful products that covered it for a long-lasting conservation. (View in reflected light, the grayness is visible).

When the lead that crimps the glasses is too weak to maintain the stained-glass vertical we, partially or totally, replace the mesh material. A justification is required before carrying out this task because it implies delicate and irreversible manipulations: the seals that have been removed can never be set back on the stained-glass. These seals have both a structural and an aesthetic role, which is why they have to be fully studied before any decision can be made.


>> Restoration consist in working directly on the damaged or tampered stained-glass in order to make the deciphering easier and at the same time respecting its aesthetic, historical and physical integrity as much as possible.

Cleaning has major aesthetic consequences: it does not bring back the original quality of the glass but transparency that will vary on the glass depending on the results of the treatment. The hardest thing in restoration is to obtain a balance in light transmission on the full scale of the monument.

Through the ages, broken glass was often assembled and preserved with what is commonly called “des plombs de casse” in French that sometimes overload the compositions to the point of making them incomprehensible. Nowadays we use adhesives that allow us to make the fracture zones as discreet as possible.

Some incomplete pieces (or pieces already completed sometimes with fancy glass during previous restorations) have to be completed. Depending on the extent of the gaps and the documentation we have in order to do the restorations required, this task would be more or less difficult and long. The new glass will not be stuck but welded with copper filets (tiffanies) so that we can distinguish it from the originals.

In the absence of the archives allowing us to do an exact replica of the missing parts, we sometimes chose the aesthetic path in order to evocate harmoniously the motif without respecting the accurate graphics. (As in the visible complement at the right of the copper filet)

The steps of a restoration are generally punctuated by site meetings that allow us to review the work and to clarify the nature of some interventions with the owner of the stained glass.

   

>> The documentation is composed of an accurate recording of images and writings, of all the undertaken actions their arguments. A copy of the report has to be given to the owner, and has to stay accessible. Any further requirement for the storage, the maintenance, the exhibition or the access to the cultural goods has to be specified in this document. The report remains the intellectual property of the conservator-restorer, and should be conserved for further references.

If graduated professionals are waiting (impatiently) for a protection of the work and consequently of a regulated access to the exercise, all of them, regardless of their specialty, agree to respect an ethical code defined by the Professional Rules of the ECCO)

Here are a few of the main principles; more information can easily be found if needed:

  • Minimum intervention : the restoration limits itself at what’s necessary for a good conservation of the work.
  • Reversibility : We have to be able to intervene without risks on a previous restoration in order to suppress it or to change it.
  • Accounting : skills and materials used should not change over time by interacting with each other.
  • Readability : Restorations have to be able to be clearly authenticated and consequently distinguishable from the original parts.
  • Preventive conservation : The restorer must assure that the conditions for an effective conservation are met.
   
   





A complicated job at the crossroads of several disciplines

The conservator-restorer’s skills in the stained-glass area, like in other fields is personal and is acquired during an advanced training currently delivered at the “Université de Paris I Panthéon-Sorbonne” and recognized by a full national certificate (masters grade). In no case can there be assimilation between personal and corporate qualification.

Selected students come from scientific sector or from art history, but over the past few years we observed an evolution toward the holders of a diploma of art works provided by “l’Ecole Nationale Supérieure des Arts Appliqués et des Métiers d’Art (ENSAAMA)”. Acquiring (before or during the training) a bedrock of knowledge of the art work is indeed indispensable to the professional practice. On this precise point, the conservation-restoration of the stained-glass if different from other specialities. Indeed, if it’s obvious that our activity distinguishes itself from artistic or artisanal activities by the fact that we don’t renovate, we don’t repair neither, we don’t rebuild what doesn’t exist anymore, and we don’t create new cultural objects, we have to admit that the nature and the function which is barrier in an architectural element brings us to think from case to case at the issues encountered and most of the time to make compromises. A gaping hole in the bay generates significant changes to the environment for other works in the edifice. For security reasons, it is inconceivable for us to leave the bay as it is, even though we can understand how we could let an armchair in a castle even if it misses one of its leg and has torn material can be left without compromising the other objects of the collection and away from the visitors that will not mistake it for a resting seat.

Similarly, an area of the glass that is excessively transparent, that often comes with an absence of color, could destroys the balance of light of the stained-glass but it could also be a nuisance to the building’s architectural perception from the inside. But let us not forget that, in the medieval aesthetic, the light transmitted by the numerous colored glass forms the white, divine and symbolic light that fills the heavenly Jerusalem. If the progressive darkening due to the aging of the gothic buildings accustomed our eyes to a shadowy effect the opposite phenomenon would hardly be acceptable.

Therefore the restorer will sometimes have to intervene on delicate matters that include both ethical rules and a judicious and justified use of the restorer’s skills.

Our professional activity predominantly concerns the stained-glass preserved in historical monuments. It is sufficient to point out that only in France there are almost 90.000 square meters of stained-glasses. It is a huge heritage and immeasurably fragile which treatment cannot be isolated from the treatment of the rest of the building and the various works it contains.

Thus practicing the Conservation and Restoration of stained-glasses is very exciting but complex since it is at the crossroads of several disciplines. Architects, art historians, chemists, locksmiths, conservators, masons, stones restorers and murals restorers are our daily stakeholders and with every single site we have to face unique issues. When we intervene on monuments that do not belong to the state we have to explain and to convince the elected representatives and technical managers not familiar with heritage restoration that their heritage should be treated in the respect of the ethical rules applied to the national heritage

In the museums, the cornerstones of stained-glass conservation-restoration are well known and acquired because at first the intervention rules were developed and specified through experiments on objects (more specifically archeological objects). Stained-glass collections preserved in museums benefit from tailored services performed by restorers selected according to much stricter criteria than for stained-glass in monuments.

   
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Difficult working conditions at the start of the twenty-first century

As explained in the next section dedicated to studies, the organization of the restoration sites in the monuments is governed by the public procurement rules, that is to say that above a certain threshold, fixed at 15,000 € (duty free), the State or the local authority must organize a competitive tendering procedure. The practice of this profession is still waiting for regulation, therefore no specific diploma is required, we only demand similar work references, along with a technical memoir which content is no longer required since it became easy, notably through the Internet, to acquire new knowledge, sometimes going as far as plagiarism.

Thus we have to evaluate the tenders coming from people, businesses, groups of people or groups of firms with various (if not non-existent) levels of qualification or training. In the Bid Committee the decision makers are not always able to differentiate the bidders. So with approximately the same file and the same references, only the prices could allow to decide among the candidates.

This “market rally” is more and more problematic for all the stained-glass professionals committed to some kind of work quality and to the enforcement of the ethical rules. In fact, the volume of proposed work is decreasing and all kinds of ridiculous offers are flourishing, and inevitably the prices are falling dramatically. The time required for each step of the restoration is incompressible and, in the “contract of confidence” between the paymaster and the restorer, the paymaster has to be confident that the works will be carried out by highly-qualified professionals. With a master’s level we expect for our young and not so young professionals an hourly wage similar to a mechanic’s for the maintenance of vehicles...
We would also like there to be a compensation for the call for tenders, because we elaborate - whenever a preliminary study does not exist or is incomplete – a detailed proposition on a great variety of works which requires a lot of work.

There is no shortage of ideas to improve the operating conditions that have an urging need of regulation, in order to maintain the high quality of our services, essential for the safeguard of the precious stained-glasses entrusted to us.

 

Some restorations performed

  • Upper Choir of the Basilique Sainte-Clotilde in Paris : Stained-glass of the Maréchal de Metz (XIXe).
  • Fifteenth century stained-glass preserved in the Hôtel Dieu in Beaune, presented during the exhibition about Nicolas Rollin.
  • Church of Saint-Nicolas du Chardonnet, Paris, Prosper Lafaye’s stained-glass (nineteenth century), Le Brun’s chapel.
  • Hôtel Dieu de Tonnerre, thirteenth century stained-glass, presented during the exhibition « L’art au temps des Rois Maudits »  of the Grand Palais 
  • Church of Bonnard, in the region of Yonne, glass roof restoration (Sixteenth century) and creation of additional panels.
  • Sixteenth century stained-glass in two chapels of the Church of Saint-Gervais in Paris.
  • Beaux-Arts’ museum in Châlon sur Saône, thirteenth century stained-glass from the Sainte Chapel in Paris.
  • Orsay Museum, restoration of the Champigneulle’s stained-glass.
  • Church of Saint-Germain-l’Auxerrois, in Paris, two glass roofs from the Maréchal de Metz.
  • Arras Museum, fifteenth century stained-glass by Peter Hemmel, presented in Colmar during the exhibition « Le peintre des chevaliers : Jost Haller et l’art en Alsace au XVe siècle »
  • Church of Saint- Eustache in Paris, nineteenth century glass roof by Gsell and Prosper Lafaye
  • Museum of the Légion d’Honneur, in Paris, restoration of the portrait of Napoléon II  by A.Echivard.
  • Castle of Saint Jean de Beauregard, stained-glass of the private chapel (seventeenth century)
  • The National Museum of the Renaissance , in Ecouen, series of stained-glass by Provins (Sixteenth century)
  • Mass grave of the Church Saint Etienne du Mont, bay 18 (seventeenth century) with double glazing.
  • Prototype restoration for the upper choir of Chartres Cathedral, angel of the bay 101.
  • Restoration of two glass roofs of the upper choir of Saint Eustache inParis (seventeenth century)
  • Restoration of 16 panels of the bay 100 in subcontracting for Avice bay 100 of Chartres Cathedral.
  • Glass roofs of L’Arbre de Jessé ( Sixteenth century),Church of Montaudin, for the DRAC Pays de la Loire with double glazing.
  • Stained-glasse of Paris City Hall, Auguste Matisse, Carnavalet Museum, Paris.
  • Glass roof (XIXe) in the chapel of the Grand Veneur’s Castle, in Soisy sur Seine.
  • Regular restoration of the stained-glass (from the Thirteenth to the Sixteenth Century) for the « Les Enluminures » Gallery at the Louvre des Antiquaires in Paris
  • Restoration of the panels (XVIe) that illustrate «  The Trojan War», in the National Museum of the Renaissance in the Castle of Ecouen
  • Restoration of the stained-glass(XIXe) preserved in Morangis City Hall
  • Restoration of the stained-glass preserved in the Saint- Cloud Museum
  • Restoration of two glazed panels (XVIe) in the National Museum of the Renaissance
  • Preparation the collections’ panel dof the Louvre Museum, in Paris, for the exhibition « France 1500 » in the  Grand-Palais.
  • Restoration of the series of panels (XIXe) of saint-François’ life from the saint-Merry’s Church in Paris for the exhibition «France 1500» in the Grand Palais
  • Stained-glass of the big windows of the “Bibliothèque du Conseil de Paris”,  in Paris City Hall.
  • Stained-glass of Rouault «Le Christ à la Colonne » for the Musée National d’Art Moderne, in Paris.