Topic outline

  • Stained Glass

    RESTORATION OF STAINED GLASS WINDOWS

    As stained glass has endured a revival at the end of the 19th Century, its manufacturing process has remained largely unchanged until the present day. Stained-glass restoration uses the same techniques as did 19th Century stained-glass production, but they are completed by specific steps, like researching and surveying. This course focuses on the restoration of the stained-glass windows of the Roman-Catholic church in Târgu-Secuiesc, a complex process, beginning on-site and mainly completed in the workshop.

    The modules are presented by the restorer coordinating the stained-glass atelier in Florești, Cluj, who has learned this trade both in the family and during formal training, and has acquired extensive experience. While presenting the technical and theoretical aspects, the restorer, accompanied by his fellow artisans, demonstrates in detail each step.

    Through 10 modules, the course follows the restoration process from the extraction of the panels from the church, their disassembling and reassembling, to their installing back in place. Module 1 deals with the removal of the stained-glass panels from the window-holes, their securing and transportation to the workshop. Module 2 focuses on the surveying of the panels` design, which will become the blueprint used during the different stages of the restoration. Module 3 is dedicated to the dismantling of the stained-glass panel, allowing for each component to be dealt with separately. Module 4 illustrates the cleaning and washing process, and the preliminary operations required. Module 5 concentrates on assessing the damage of the panel after it has been disassembled and identifying the components that have to be replaced. Module 6 shows how glass shards from a shattered section are joined together with adhesive, under UV light. Module 7 details the reconstruction of the missing fragments to be replaced, including the reproduction of the pattern and the identification of similarly colored mass-produced glass elements. Module 8 is concerned with the fabrication of the new lead came, through melting and laminating the old lead cames. Module 9 presents the last steps of the restoration process, in which the panel is reassembled with new lead came, according to the initial blueprint, and then soldered. Module 10 outlines the preliminary research - undertaken before the panels were removed from their original position - that includes historical inquiry, surveying and photographing of the stained-glass windows, identifying the types of degradations and the appropriate interventions, and testing some of the proposed solutions. Thus, the course gives a detailed overview of the techniques and steps implied by the restoration of stained-glass panels.       

    At the end of the course, participants will be able to:

    • Grasp the complexity of the restoration of stained-glass panels, theoretical and practical;
    • Be familiar with the preparatory steps to be taken on-site;
    • Learn the succession of operations implied by the restoration of the stained-glass panel in the workshop;
    • Acknowledge the types of damages that can be sustained by stained-glass windows and their subsequent remedies; 
    • Understand the importance of finding and testing suitable techniques and materials to be used in the process.

    • Part 1

      • Tutorial Video - 1 Page
        EXTRACTING THE STAINED GLASS FROM THE SITE AND TRANSPORTATION TO THE WORKSHOP

        Shortfilm - Length: 5 minutes 44 seconds
        Original language of the film: Romanian
        Subtitles: English, Estonian, Hungarian, Lithuanian, Portuguese, Swedish, Romanian

        Description of processes shown in the video: The first module of this course begins with the extraction of the stained-glass windows of the Roman-Catholic church in Târgu-Secuiesc, an 18th-century church known to the locals as "Kanta".

        The initial step implies worksite organization, namely putting up the scaffolding. Secondly, the stained-glass panels are carefully removed from the window openings, eliminating whatever materials were used to hold them in place without damaging as much of the original substance as possible. After each of the six stained-glass panels that compose one window is fixed on a rigid wood panel, they are securely lowered from the scaffolding in batches, together with their support system – metal rods, and transported to the workshop in Cluj, where the restoration process is set to begin. The cleaning operation is followed by the surveying of the panels` designs, at a 1 to 1 scale. The symmetric composition makes the missing parts easier to reconstruct, using identical or similar compatible materials and techniques. Henceforward, all actions rely on the theoretical restoration study preceding the project that contains descriptions of the techniques and materials used, historical data regarding the panels` manufacture and mounting in place (1902-1907), and a damage assessment. The latter exemplifies how humidity, wind pressure, or physical shocks, have led to the glass sagging under its weight, and later detaching from the lead came.

        These operations require knowledge passed from generation to generation or completed in (Art) College, now shared with a young collective in order to assure its continuity into the future. ... MORE  >>

    • Part 2

      • Tutorial Video - 2 Page
        TRACING THE LEAD CAME DRAWING

        Shortfilm - Length: 6 minutes 16 seconds
        Original language of the film: Romanian
        Subtitles: English, Estonian, Hungarian, Lithuanian, Portuguese, Swedish, Romanian

        Description of processes shown in the video: After a closer inspection of the stained-glass panels, the preliminary damage assessment is further elaborated: deteriorations that were not apparent from the start are now visible. One such case is the narrow glass fringe of the stained-glass panel, usually fixed into the window opening. The glass hem, made of cheap, unpretentious glass, has its origins in the Middle Ages, when stained-glass windows, demanding a serious investment on the part of the community or church, would have to be easily removed and put back into place. As the tradition was carried into the middle of the 20th Century, the glass fringe was meant to be replaced, as it has been in the present case; this explains the contrast in quality with the adjacent material: manually painted glass.

        At this point, the panels are precisely measured; afterward, the design of the lead came network is traced through rubbing a wax crayon on a sheet of paper fixed with nails on top of the panels. The operation is repeated another time, resulting in 2 copies of the design, which also chart any observations regarding damages (missing or cracked components), include information for easier identification – window and glass panel number, and indicate the position of the support rod and the soldered wire. The first sheet will be layed under the cleaned and disassembled stained-glass components, after being detached from the lead came, while the second sheet will be used as a blueprint for reassembling the stained-glass elements into the new lead came. ...  MORE  >>

    • Part 3

      • Tutorial Video - 3 Page
        REMOVING THE OLD LEAD CAME AND DISASSEMBLING THE STAINED-GLASS PANEL

        Shortfilm - Length: 5 minutes 51 seconds
        Original language of the film: Romanian
        Subtitles: English, Estonian, Hungarian, Lithuanian, Portuguese, Swedish, Romanian

        Description of processes shown in the video: After finishing the 1 to 1 scale drawings, the old lead came - worn because of “metal fatigue” and the effects of other mechanical, weather of chemical interventions - is removed. Firstly, the lead came is detached; afterward, the glass components are removed, washed and cleaned, and successively placed on the first drawing sheet, as each component is easier to locate one at a time. Like in the past, the lead came is first poured and then molded into wands that are laminated several times, until they reach the desired dimensions – varying from a 4 mm section to 12-14-20 mm, depending on the thickness of the lines in the drawing. Obviously, restoration work implies the exact replication of the original lead came specifications – the same width, thickness, length, composition, and profile. ...   MORE  >>

    • Part 4

      • Tutorial Video - 4 Page
        CLEANING AND WASHING INDIVIDUAL STAINED-GLASS COMPONENTS

        Shortfilm - Length: 5 minutes 47 seconds
        Original language of the film: Romanian
        Subtitles: English, Estonian, Hungarian, Lithuanian, Portuguese, Swedish, Romanian

        Description of processes shown in the video: At this stage, the panels` lead came has been removed sequentially, in six steps, so to maintain an easier control of the process. After the glass components, which have now been freed from their support, are soaked in soapy water, washed individually, and set to dry on a cotton rag, they are placed back on top of the second lead came network drawing. At this moment, new details emerge about the condition of the glass – fissures and cracks earlier concealed by the lead came, or by dirt and dust, clearly suggesting the next steps that have to be undertaken. It is now evident which are the pieces that can be glued together, which are the ones that only need cleaning, and that can be placed back in the new lead came as they are, and which of them are completely missing or deteriorated to a large extent, and are in need of replacement or further repairs. Such a component, probably shattered by a stone, will be reviewed at a later time.

        Prior to washing the stained-glass elements, the ratio and type of soap have been established through several tests, in order to avoid a high amount of detergent or other chemical agents that could harm the glass surface. The use of neutral soap, as in the present case, simplifies the procedure; when dealing with delicate components, other chemical agents have to be avoided altogether, and only distilled water can be added. ... MORE  >>

    • Part 5

      • Tutorial Video - 5 Page
        PLACING THE STAINED GLASS BACK

        Shortfilm - Length: 5 minutes 37 seconds
        Original language of the film: Romanian
        Subtitles: English, Estonian, Hungarian, Lithuanian, Portuguese, Swedish, Romanian

        Description of processes shown in the video: As the washed stained-glass components are successively overlayed on the second of the two lead came drawing copies, elements that have suffered mechanical damage or have gaps, undergo complex interventions. Before reassembly, these pieces are partially pasted, joined together with lead came, while some fragments are replaced with newly baked painted glass.

        Initially a single piece of glass, such an element - probably hit by a rock, has cracked radially from the shattering point. Now missing some of the shards, it cannot be reconstructed as it now presents itself. Therefore, the larger shards surrounding the crack will be glued together with a UV-curing adhesive and, if necessary, will be also reinforced with lead came, eventually resulting in a visible new thin line. The missing central part, composed of small shards, is going to be replaced with an identical or similarly colored mass-colored piece of glass that will be integrated with shading or enamel paint, in a process to be explained later on.

        Mass-colored glass – used in restoration projects or new designs, is sold in a wide variety of textures and colors by several European producers, specialized in traditional techniques or even manufactured goods that resemble historical materials. If for some reason, a particular color cannot be found, other techniques can be used in order to bring it closer to the original tonality. Coloring is done at room temperature, before the pieces are baked in the oven at temperatures between 580-620 degrees Celsius, depending on requirements of the pigments used. ... MORE  >>

    • Part 6

      • Tutorial Video - 6 Page
        GLASS PASTING TECHNIQUES

        Shortfilm - Length: 8 minutes 10 seconds
        Original language of the film: Romanian
        Subtitles: English, Estonian, Hungarian, Lithuanian, Portuguese, Swedish, Romanian

        Description of processes shown in the video: The disassembly process has exposed the actual state of the stained-glass components, revealing a large number of well-preserved elements that only need reassembling and a smaller number of damaged ones, either cracked, severely broken or lost. Such a completely missing part was covered with duct tape while on-site, to prevent water from entering the church. Another small element, shattered into eleven pieces, is extremely damaged.

        Uncomplicated situations only require gluing together cracked fragments: at first, the contact surfaces are cleaned with an alcohol or a diluent-based solution, then a very thin layer of special adhesive gel is applied. After the shards are aligned and positioned, they are held by hand vertically under UV light, so the upper shard`s own weight eliminates any air bubbles or impurities that could make the seam visible. When the piece has partially solidified, it can be left to harden by itself under UV light, for another 5 to 10 minutes. The process will be repeated as many times necessary.

        When dealing with more shattered pieces, as much original material as possible has to be reused - and the gluing together is done according to size, by first joining the smaller shards, in order to obtain several large fragments that are more easily fitted together. If the seam line between two fragments is visible - maybe because of missing paint, and a newly inserted black line would not distort the drawing of the panel, it is recommended to use lead cames instead of adhesive. ... MORE  >>

    • Part 7

      • Tutorial Video - 7 Page
        RECONSTRUCTION AND REPLACEMENT TECHNIQUES OF THE MISSING PIECES

        Shortfilm - Length: 7 minutes 22 seconds
        Original language of the film: Romanian
        Subtitles: English, Estonian, Hungarian, Lithuanian, Portuguese, Swedish, Romanian

        Description of processes shown in the video: The earlier mentioned element, broken into 11 fragments, calls for a different approach. With our first objective in mind - to keep as much original substance as possible - all the shards are bonded one by one until the final two pieces can be joined together with lead came. If - when connecting the pieces, light spots are present, or the crack is still visible, it means the contact surface is badly damaged, and smaller fragments still missing prevent a tight fit, so the element needs replacement entirely.

        This process necessitates first finding a matching mass-colored piece of glass, then browsing through the enameled glass samples in the workshops' collection, previously numbered to ease identification. Overlapping the two sample types gives an impression of the final result, which after being painted and baked, will come closer in hue and shade to the original. When choosing the right color, the reference has to be the lightest area of the original, to allow darker tones of paint to be overlaid, and also to integrate the non-painted areas. There are two possibilities: enameling the pieces or using them as is.

        Next, the painted motif of the original is copied integrally on a transparent sheet, which will be positioned on top of the missing fragment. In this particular case, the pattern is repetitive. Coming up, the piece is painted uniformly with metal oxide matching the darker shades of the original, and the pattern is revealed by removing the paint wherever the drawing requires lighter parts. Lastly, the finished piece is baked. ...  MORE  >>

    • Part 8

      • Tutorial Video - 8 Page
        MELTING AND REMODELING THE LEAD CAME

        Shortfilm - Length: 6 minutes 18 seconds
        Original language of the film: Romanian
        Subtitles: English, Estonian, Hungarian, Lithuanian, Portuguese, Swedish, Romanian

        Description of processes shown in the video: As seen earlier, the disassembly of the stained-glass panels has been preceded by the surveying of the design. It has required separating the glass fragments and recovering the old lead cames. Since the latter cannot be utilized in their present condition, they are going to be melted, then recast into wands, and laminated in a two or three-phase process, similar to the one that produced the initial cames. Of course, newly-acquired lead will also be added, but the aim is to reuse the original material. After it has melted and any impurities have been removed, the liquefied lead is poured into a mold, giving shape to raw wands, a little thicker than needed, which have to be further laminated.

        The lamination process has two or three stages, requiring the recast wands to pass several times through different profiles from the collection of the workshop, in order to replicate the characteristics (exterior size, interior size, girth) of the original lead cames. 

        In this particular restoration project, two types of cames have been identified: a wider one, which is 8 mm wide as seen from the front, and a narrower one, which is 6 mm wide and has an interior dimension of 4 mm. This means the height of the section of the H-profile of either of the two types of cames is 6 or 8 mm, while the distance between the two sides of the H – the breadth, is 4.5 or 4 mm. ...  MORE  >>

    • Part 9

      • Tutorial Video - 9 Page
        REASSEMBLY OF THE STAINED GLASS IN THE NEW LEAD AND SOLDERING

        Shortfilm - Length: 7 minutes 23 seconds
        Original language of the film: Romanian
        Subtitles: English, Estonian, Hungarian, Lithuanian, Portuguese, Swedish, Romanian

        Description of processes shown in the video: By now, almost all the steps of the restoration process have been finalized. After every glass component has been either cleaned, glued, or replaced and the new lead cames have been produced, the panel is ready to be put back together again. This operation will employ the same techniques as 100 years before, so the stained-glass window will go back looking as it did when it was first manufactured.

        The reassembling takes place on top of the second blueprint of the lead came structure; it begins with one corner of the panel and continues until completion by gradually joining all the stained-glass fragments with lead came. Subsequently, first, the intersections of the lead cames are soldered, and then their entire surface (of the front side and the backside) undergoes the same treatment. The last stage of the restoration process has been reached once the stained-glass panels have been carefully packaged in wooden boxes and transported on-site, where they have been installed back into their original places, and the grout has been cleaned with sawdust. Finally, the windows have been sealed in the structure with lime-based mortar. Besides reconstructing the missing part of the stained-glass panel, perforated by an exhaust pipe, the restoration has also entailed replacing the adjoining concrete plaster patchings with lime mortar and practically rebuilding a small part of the brick wall. Once in their original position, the windows can be contemplated, their newly replaced parts completed and visible. ... MORE  >>

    • Part 10

      • Tutorial Video - 10 Page
        TECHNICAL DOCUMENTATION OF THE RESTORATION PROJECT

        Shortfilm - Length: 5 minutes 31 seconds
        Original language of the film: Romanian
        Subtitles: English, Estonian, Hungarian, Lithuanian, Portuguese, Swedish, Romanian

        Description of processes shown in the video: As before mentioned, the restoration process stands on a lengthy study of about 80 pages for the four windows, including an introduction to the history of the church building and a location analysis of the stained-glass components inside. Next, the overview of the stained-glass windows about to undergo restoration contains descriptions of the panels' themes, details about their placement, and information about their authors - in this case, Walther Gedeon and Ligeti Sándor.

        Further on, each panel is presented individually - more specific data include dimensions and a digital survey of the lead came network, completed with the help of frontal photographs, taken perpendicularly, at close range, by drone. The “Identification sheet of the types of degradation of the stained-glass window about to be restored” analyzes the current state of preservation, assessing the extent of the damages and describing and explaining all issues such as cracks, dents, gaps, detached parts, adherent deposits on the glass surface, cover-ups with other materials, cracks of the lime plaster used to seal the windows in place, etc. An appropriate solution, including all the steps of the restoration process, is prescribed for each entry. Glass samples from each damaged area are taken and subjected to tests, in order to identify the suiting restoration method to be employed. As an example, in the case of a missing corner of one of the windows, the intervention was simulated using a digital reconstruction, that was later printed on a 1:1 scale to be used in the actual restoration work. ...  MORE  >>

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