Sunday, February 6, 2011

Creating Successful Period Stained Glass

When building a historical period-style home, there are many important elements to consider in successfully creating the proper aesthetic.  Among these, stained glass is often one such element.

While it is possible to locate and purchase antique stained glass panels to design into a new home, the availability of truly great pieces is quite limited and are often in need of repair or full restoration before being utilized safely.  It is precisely these sorts of limitations in design, size and condition that cause most people to turn to stained glass artists to create new custom pieces that better suit their individual needs.  However, making the decision to do so is just the beginning.  After a little research into the variety of work being produced today, it will quickly become evident that not all stained glass is created equal.

Windows on the right are Victorian antiques, window on the left is new.
What is it that makes some stained glass appear brand new and others commonly mistaken for true antiques?  Whether it's a simple organic Arts & Crafts window or an elaborate jeweled Victorian, there are several factors that combine to create a successful period look.  Among these are design, scale, color, texture and density.  Although design would seem to be the most important in this list, proper glass selection is equally important.  You could copy an antique window line for line but unless appropriate glass colors and textures are used to create the reproduction, all sense of authenticity will be lost.

Stained glass is a term used today to describe panels and three-dimensional objects that are made of individually-cut pieces of colored glass and assembled within a metal matrix.  Traditionally this matrix is made with lead but can also be copper, zinc or brass. The origin of the term stained glass actually comes from two different methods of coloring the glass: The first involving the addition of metal salts to glass during its molten stage to "stain" it certain colors and the second, the application of vitreous paints and stains onto the surface of the glass, which are fired to produce a variety of colors.  Silver stain, a gum mixture containing silver nitrate discovered in the 14th-century, quite literally leaves behind a gold, amber or brown stain when fired onto the glass. 

Hand-painted stained glass can range from simple decorative elements to elaborate enameled pieces more closely resembling classical oil paintings than stained glass windows.  The variations one sees in painting styles over the centuries are often indicators of the age of a piece because they are direct reflections of the tastes and cultural attitudes of the time.

Leaded glass is another term commonly used to describe stained glass but was originally used to describe clear glass that was made with a high lead content to increase it's refractive index, much like crystal stemware.  This "leaded" glass was cut into shapes, beveled and polished then assembled together to create windows with a spectacular prismatic effect.  Modern beveled glass is typically made from standard plate glass so it does not contain the high lead content and is therefore less brilliant than it's antique predecessor.  Although leaded glass could technically be used today to describe any glass involving lead, whether in content or method of fabrication, it most accurately describes any clear glass that is joined together with lead came in the traditional manner.

Stained glass begins its journey as large sheets, which are then cut, shaped and assembled by stained glass artists to create finished stained glass works.  This sheet glass is produced by a handful of manufacturers in the US and abroad, some of which have been in existence for over a hundred years.  Each manufacturer typically creates several lines of glass, ranging from transparent to opaque and some possessing both of these qualities, depending on whether the light is transmitted or reflected.  Manufacturing processes differ as well, ranging from machine-made to glass that is made completely by hand.  

Because of the wide age range of current manufacturers and the fact that their lines are quite distinct, it's important to know a bit of their history in order to make appropriate choices when creating an authentic looking period piece.  In addition, the overall history of stained glass contains several period indicators based on the development of certain materials and techniques, so these are important to know as well. 

For instance, Opalescent Glass, a type of glass ranging from completely opaque to semi-translucent, was invented in the late 19th-century.  Prior to that, sheet glass was largely transparent in nature, whether completely transparent or slightly textured. The earliest glass of this type used in the production of stained glass windows was first blown into cylinders, scored, opened and then reheated to lay flat, creating rectangular sheets.  

This mouth-blown glass, referred to as Antique, is still being produced today in the same way it has been for centuries.  Because of the hand-made nature of this glass, each sheet is unique, containing striations, bubbles and/or small seeds (small bubbles), which are considered highly desirable.  There are a variety of machine-made simulated antiques (New Antique) out there today but they lack the brilliance and unique characteristics of their mouth-blown predecessors and are clearly detectable to the informed eye. 

A common example of this difference in manufacturing techniques can be seen in the window glass of today, called Float Glass, because it is made by floating molten glass on a layer of tin.  Prior to the 20th-century, window and cabinet glass was made by hand, which caused slight irregularities that subtly warp what is being viewed through it.  Looking at this glass at an angle with a light source reflected on it's surface will reveal these surface irregularities, providing an indication of possible age.  A very successful reproduction of this glass is available today called Restoration Glass, which comes in either Full Restoration or Light Restoration, depending on the time period you are choosing to emulate.

Besides glass choice, there are other important factors as well, such as fabrication technique.  The use of lead came - lead strips which are placed between the pieces of glass, soldered  to hold them together and reinforced with steel bars or iron rods - is the most traditional method, with certain sizes and profiles used to reflect different eras.  Another method of fabrication was developed in the late 19th-century involving the use of copper foil and solder.  This technique is mostly commonly attributed to Louis Comfort Tiffany but there is debate whether he actually invented it or if it was the work of his contemporary, John LaFarge. 

With so many factors to consider then in creating an authentic period stained glass piece, it's important to select artists with not only skill and attention to detail, but also a solid knowledge of the history of their medium.  This, combined with an artist's personal passion for antiquities ensure that their addition to your environment will blend seamlessly and exemplify this time-honored tradition.  And although the price is often higher for this type of hand-crafted excellence, most with an eye for detail and quality will agree, it's well worth the investment.  

Wednesday, February 2, 2011

Too Big For Its Britches

Today marked the completion of a two-day on-site restoration of a large residential stained glass window in New Brighton, MN, featuring a hand-painted castle scene in its center.  The window is only about 15 years old but because it was originally fabricated with insufficient structural support, the bottom border was already folding in on itself and the lower floral areas were beginning to bow.   

In consulting with the client, I came up with a plan that would ensure he would not have to deal with this window again during his lifetime.  The window was removed and carried to a lower level garage where folds and bulges were flattened out through a combination of heat and careful hand manipulation.  Next, broken glass pieces were matched and replaced, followed by the creation of a steel support grid compromised of interlocking vertical and horizontal brace bars, which was then soldered onto the outside of the stained glass.

Typically, brace bars are applied to the inside of stained glass windows but since there was enough clearance between the stained glass and the insulated glass unit behind it, I was able to hide a fairly extensive amount of steel, providing a much more attractive interior view.  After this, the old brace bars (two small 3/8" steel horizontal supports!) were removed from the inside of the panel, solder joints smoothed out and darkened to match the old, then the window was reinstalled. 

This window, nearly 6' x 5', is a perfect example of why you should never create a panel that exceeds the 4' x 4' maximum panel size rule of thumb. When you get past four feet in both directions,  a new dynamic occurs in the center of the panel that is very difficult to manage with standard horizontal bracing alone.  You almost always have to incorporate vertical as well.  

Some of you non-industry people may be saying, "But church windows are way bigger than 4' x 4' and they're just fine?"  The trick here is that the design may look continuous but the window is almost always broken up into smaller panels that are either stacked on top of one another using slip joints or divided by steel or iron t-bars anchored into the wood frame to help distribute the weight.  Rarely will you see a window this big fabricated in one piece and if you do, you will hopefully find that someone has reinforced the hell out of it.  If not, um... you might want to step back a bit.  

Master Bath Transom

The latest project: A leaded glass arched transom as part of an extensive remodeling project in Mendota Heights, MN. The design emulates a larger leaded glass arched transom in the client's front entryway and the clear textured glass was matched as closely as possible to create a seamless exterior look between new and old.
Interior designer: Bruce Kading