Glass Art - May/June 1996
Dialogue in Design
Creating Work for a Glass Tower
As an architectural art, the success of stained glass depends a great deal on how it works in context. Over the years, and through many commissions, I've gained a respect for buildings, and an understanding of the importance of designing works that fit within and complement their environment.
An essential part of every commission is to observe the window's surroundings - to "listen" to the building, and to respond with an artwork that is right for the space. This can be difficult when there are so many other demands and expectations to be considered: Architects, clients, and even passersby all have ideas about what the window should look like, and what it should do. I have to remind myself that the time scale of buildings and windows is not the same as that of us mortals. They will be here long after we have passed on, and if only for this reason, the window must be right for its surroundings.
There are a number of considerations to take into account when creating art for a site. First and foremost is the light. Light is life to a stained glass window, and how the window interacts with the light in its environment will make the difference between a piece that "breathes" and glows with color, and one that disappears into shadows and reflections.
Each design must take into account the quality, direction and amount of natural light the window will receive through the day and over the seasons. This means considering not only the changing intensities and angles of light, but the changes in trees and other vegetation outside the window as well. The source, intensity and spectrum of artificial light and light from other windows that the piece will receive are also important. In complex lighting situations, we build a model of the window and its surrounding architecture, and then recreate the lighting conditions it will encounter.
Closely allied to the issue of light is that of the role of the window in the space. Is it intended to attenuate the natural light, or to catch and amplify it? Is the window expected to provide privacy or block an uninspiring view - or is it to frame and highlight the surroundings? This also involves thinking about where the piece will be seen from, and how it will be seen. Will it be viewed for long periods in a meditative space, or will it be in a transitional space, and seen only in passing?
The size and shape of the window are the most obvious preconditions for any design, and they are of course integral to every design decision. As I gain a sense of the light conditions and the role of the window, I am also considering its dimensions, from both a practical and an aesthetic sense.
On the practical side are considerations of structural integrity, and of the maximum dimensions of different types of glass stock. The way the window is divided, and the practicalities of installation are taken into account.
Aesthetically, the piece must be considered in terms of how it relates to human scale. A large window intended to be seen at a distance will have a different level of detail from a smaller one designed to be seen up close.
Last, and certainly not least, is the important issue of the style of the building. Whether I am designing to match a style, or to give a contemporary response to an older style of building, an awareness of the architectural context shapes and directs my design.
All of these elements - light conditions, the role of the window, its size and its style - are important. But taken together, they do not make a design. Rather, they provide a focus; forming a foundation upon which an artwork can be created. Other important input is provided by the window's theme; the suggestions of clients, users and architects; and the budget of the window, which will help determine the type of materials and techniques to be used.
With these influences in mind, I begin the design process by sketching several different ideas. As I work with these, I try to picture each of them in the space from different angles and under a number of lighting conditions. Eventually, the ideas are narrowed down and combined, until I am working on just one. I begin to "see" the work in the space, and the artwork takes on a life of its own.
A good example of how design and site work together can be seen in "Radiance, Reflection, Revelation", a work our studio recently completed for the First Unitarian Congregation of Toronto.
The Congregation's original building was a modest brick structure, dating from the 1950s, which was tucked far back from a busy street near the downtown area, and overshadowed by surrounding buildings.
In the 1980's, the Congregation realized that it was outgrowing their building. Rather than move to a larger structure elsewhere, they decided to build onto the front of the building, extending it towards the street. This would create more space, bring in more light, and make the building more visible and accessible.
The addition was designed by Murray Ross of Brown, Beck & Ross Architects. The new section represents a masterful expansion and reorganization of the existing building. The focal point of the front of the building is an immense glass tower which rises 50 feet above the main doorway.
The role of the window is to work within the tower to bring natural light to the inside, and to act as a beacon to the outside. In addition, it was intended to convey a strong spiritual and inspirational message which would be understandable from both inside and outside and from any distance. Privacy was not an issue; nor was there any wish to block a view.
As I began to design, I considered the challenges and opportunities presented by the building. My first concern was with light. The original building faced north, and because the Congregation wanted the facade and the tower to interact with the sidewalk and street, the addition and the tower extended towards the north. The design of the addition acknowledges the challenges of the building's orientation, and makes the best possible use of the available light. The glass tower rises well above the roof line of the building, slicing through it, and sloping at an angle towards the south for 10 feet. This has the advantage of letting south light into the space, and making this light available to the window. It also presented a potential problem with reflections on the interior glass.
The design would need to make the most of the available light, to bring colour and life to the outside of the tower. At the same time, I had to make sure that reflected light would not compete with the stained glass on the inside of the tower. My solution was to work towards a light, open design, using textured clears, bevels, and antique flashed whites and varying shades of golden yellow. This would allow light into the tower through the top, and it would let additional light pass through one side of the V-shaped tower and be transmitted through the other.
The size of this window provided me with a wonderful opportunity to work on a large scale; at the same time, it presented significant challenges. In planning for scaffolding and truckloads of glass, it's especially important to maintain the artistic integrity of the work, and the sensitivity to context. I had to make sure that the piece would speak to its audience and have enough detail to engage them.
In terms of style, the addition put a contemporary face on a 1950's era building. This was achieved so well that the older building is seamlessly incorporated into the new. The line and sweep of the addition were easily extended into the style of design I had in mind.
My inspiration for the window design was taken from the Unitarian symbol of the flaming chalice, and from the tower's relationship to the building. The tower rises through the building like a crystal prism in its natural stone matrix, symbolizing the spiritual presence within the rational body. The flaming chalice within the prism is intended to bring a mystical, totemic presence to the tower. A spiralling flame winds up through the tower, symbolizing the ongoing revelation. It passes through a column of clear bevels, crystals, prisms and textured clear glass. The outer windows are of handmade panels of translucent flashed white opal glass.
The stained glass can be "read" from both inside and outside the building. The flame-like shapes within the spiral are made from dichroic glass. This glass has some wonderful properties; most notably, a capacity to reflect light in an ever-changing spectrum, and a complementary capacity to transmit other wavelengths of light to an extraordinary degree. This choice of glass allows the tower installation to be viewed from the exterior during the day, as it casts beautiful colours onto the sidewalk and street. At night, the tower serves as a beacon of colour and light to enliven the city landscape.
Designing stained glass for buildings has its challenges and its rewards. The challenges of light and environment can be best met when the artist takes time to look, and listen, and reflect on the site. The rewards come when one can look at an installation - either one's own or another's - and feel that it "belongs" in the site. Such a window is a gift - both to the building itself, and to the future generations that will see and enjoy it.
Techniques
The stained glass in the First Unitarian tower was made using the traditional, lead glazed techique. The large panels utilize some zinc channelling in addition to the lead to provide extra strength and rigidity. The glass used for the central core is textured clears with bevels, crystals and prisms. Hand-made European glass is used in the surrounding panels, and dichroic glass is used in the flame shapes.
The use of dichroic glass was especially appropriate in this piece because of its unique qualities which allow it to provide dramatic effects from both inside and outside of the building. The dichroic glass used in the window, which provides exceptionally sharp colors, was custom-made by Randy Domm, of Applied Physics, in Toronto. Mr. Domm describes the production of this glass:
Dichroic filter glass is made by coating a piece of clear glass with multiple layers of specially selected dielectric materials. Usually two dielectric materials, one with a high index of refraction and the other with a low index of refraction are used in alternating sequence to form a multi-layered coating. A typical dichroic filter could use a quality optical glass such as quartz or even ordinary window glass as the base material. The dielectric layers would be made up of metal oxide materials such as hafnium oxide and silicon dioxide.
The layers of dielectric material are deposited on the glass using a process called vacuum deposition. This is done in a vacuum coating plant, which consists of a large vacuum chamber and vacuum pumps. Inside the chamber there are holders for the glass to be coated, a device to melt and vaporize the various dielectric materials, heaters, and instrumentation to measure vacuum pressure, temperature and layer thickness.
In a typical production run, the glass to be coated and the required dielectric materials are placed in the chamber, and the air is pumped out. When the required vacuum pressure and temperature are attained the first dielectric material is melted. As it becomes hotter it vaporizes and travels through the vacuum, depositing on the first surface it hits (the glass). When the required thickness is achieved, the melting is stopped and the next material is applied by the same process. When all of the layers are complete the chamber is allowed to cool. It is then pressurized, and the resulting dichroic filter glasses are removed and ready to be used.
The appearance of the filter is dependant on the thicknesses and number of layers deposited. The layer thicknesses are measured in nanometers, or billionths of a metre. Layer thicknesses are typically 50 to 150 nanometres and five to eleven layers are used. As light enters the filter multiple reflections occur between the thin dielectric layers causing an optical interference which results in some wavelengths (or colours) being transmitted through the glass, while other colours are reflected. Coatings made with thicker layers appear more bluish in reflection and reddish in transmission.
As both the base glass and the dielectric materials are non-absorbing, the colours observed in either transmission or reflection are very bright. As the angle at which you view the glass increases a colour shift toward the blue end of the spectrum occurs. For example a red filter would appear green, and then blue in reflection as the filter is rotated to a greater angle. One final point about the filter is that as the coating is made up of hard metal oxide materials it is very resistant to scratching or peeling.
