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painted silver-stain

Discussion of Painted v. Stained?

Photo Above:  Portion of Gothic Influence stained glass window featuring areas of silver stain (gold tones).  The black painted detail is pigmented glass paint. 

 

Painted narrative windows such as pictured above are generically referred to as “painted stained glass”.  The paint is a specially formulated pigment designed to fire permanently into the surface of the glass. Once properly fired, the paint will not peel or fade… it is very much permanent.  This process and terminology is a bit confusing when you consider the namesake “stained” glass.  The term “stained” actually refers to another process of adding color to glass called “silver staining”.

 

Silver stain is applied to glass in the same way as glass paints.  However, when silver stain is fired it actually changes the surface of the glass and therefore the color.  Silver stain adds a gold tone to the glass and was widely used in the production of medieval stained glass. Unlike glass paints which impart a pigment onto the glass, silver stain actually does stain the glass… there is no pigment in silver stain.  We selectively use silver stain today for similar result… to add a beautiful gold tone to the window.

damaged windows

Repairing Damaged Windows

Repair of damaged stained glass windows varies from a single shattered piece of glass to replication of several missing pieces.

Replacing a single broken piece of stained glass: It is possible to replace a single piece of glass without removing the window panel.  A rubbing is made of the broken piece to use as a pattern to cut and, if necessary, painted to match the existing window design.  The new piece of glass is then carefully installed into the damaged window.

Replacing several broken pieces of adjacent stained glass:  This type of repair is more difficult to accomplish in place.  Often the lead is mangled and/or stretched.  Typically a repair of this nature requires the removal of the panel.  New pieces of stained glass glass are cut and, if necessary, painted to match the existing window design.  The lead in the damaged area is replaced with new lead came.  Depending on the age and condition of the window,  the recommendation may be to completely re-lead the damaged panel.

solder joint

Broken Solder Joints

Broken solder joints are a sure sign that a stained glass window is under duress.   As a window ages, the lead structure within the window gets brittle.  Brittle lead is more apt to crack under stress.  Stress can come from multiple of sources:

  • The weight of the stained glass:  The panel weight us supported by the lead structure.  As joints break, the weight redistributes thus adding more stress to the remaining joints.  Therefore lead breakage is a progressive failure increasing in severity if left unchecked.
  • Expansion and contraction due to temperature fluctuations:  Although not visible to the human eye, window materials expand and contract daily with fluctuations of solar temperature.  These tiny movements stress the lead, sometimes even pushing the window out into a bowed condition. Repeated expansion and contraction introduces material fatigue which weakens the lead. A good example of this is a simple paper clip.  Bending a paper clip back and forth weakens the material and intimately results in breakage.  Similar is the break olead due to expansion and contraction.

Broken lead often occurs at the solders joints.  This is because of the difference in material properties between the lead and solder.  The solder joint is harder than the lead thus the lead usually breaks at the edge of the solder joint instead of through the solder joint.

Depending on the age and condition of the lead, repairing these broken joints can be difficult to accomplish.  Often this condition is a sign that the window is in need of re-lead restoration.  Re-lead restoration is the process of removing, dismantling, and reassembling the window with new lead.

Faded Paint on Antique Stained Glass

The traditional art of crafting stained glass often includes painted detail on the glass. The paint is fired at a high temperature to permanently set the paint into the glass.  Unfortunately, history tell us that this process was not always executed successfully.  A window which has not been properly fired can result in unstable paint; evident where painted detail has faded or is completely missing.

Unstable or faded paint is the result of under-fired glass paint. Glass paint is permanently set into the glass at approximately 1200 degrees F.  At lower temperatures the paint will not set and therefore is not permanent.  Under-fired glass paint has a dull matte finish and will fade over time.

Treatment of Unstable or Faded Painted Glass

Painting on stained glass requires that the painted piece be fired at a high temperature to permanently set the paint into the surface of the glass: approximately 1200 degrees F.  If fired too hot the paint merely burns away.  If fired too low the paint does not set properly and will fade over years of service.

We do not recommend adding paint to the existing painted glass in an effort to replace what is missing.  The firing process which sets the new paint can burn off the remaining unstable paint and may not accomplish the desired result.

The recommended repair may vary depending on the type of window and wishes of the church.

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bowing stained glass

Bowing in Antique Stained Glass Windows

One of the most common problems found in antique stained glass windows is out-of-plane bowing. Window bowing is a progressive failure and can take years to become a serious problem. However, other factors can accelerate the condition.

  • Oxidation of the lead:  Oxidation is the white chalky substance that appears on the exterior of the lead. Extreme oxidation can weaken the lead and thus the window.
  • Brittle lead:  Window leads get brittle with age and become prone to breakage at the solder joints.  Broken joints weaken the overall window.
  • Breakage of wire ties:  Twisted copper wires bond the stained glass window to bracing rods extending across the window.  This is designed to support the weight of the window and keep it flat. These wire ties can break over time and lessen their support to the window.
  • Building settlement:  Settlement can induce pressure on the perimeter on the window. This pressure is relieved as the panel bows.
  • Fluctuations in temperature:  Stained glass is exposed to a range of daily solar temperature change. As the window heats it expands.  As the window cools it shrinks. This daily heating/cooling cycle creates stresses in the stained glass which are relieved by out-of-plane bowing.

Bowing ultimately allows stained glass to work free of its confining lead, in some cases actually dropping glass.  Bowing can result in broken glass.  At the very least, windows may become less weather resistant.

Inward bowing is partly confined by steel brace bars; with bowing generally occurring between the brace bars.  Outward bowing can be more pronounced, in some cases breaking the wire ties designed to secure the window to the brace bars.

Window bowing cannot typically be repaired in place.  The window will require removal to flatten.

If the window is generally in good condition (other than the bowing) it is possible that the panel can be flattened and reinstalled.  However, more often than not, the window is old enough that is has many of the degrading symptoms described above. If this is the case, it is possible that the window will require re-lead restoration.

Re-lead restoration is the process of dismantling, cleaning, and reassembling the window, replacing the old lead with new restoration grade lead.  Structurally speaking, the result is a “like-new” stained glass window. The recommendation for re-lead comes after careful consideration of the project as a whole.

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choose a studio

Choosing a Stained Glass Studio

Comparing Religious Stained Glass Window Quality:

There are numerous options to consider when commission religious stained glass windows. Generally, they include window design style, glass type, hand-painted detail, and design intricacy. 

Stained Glass Design Style:

Window styles range from very abstract, contemporary work to very traditional, handpainted work. Not all studios are capable of producing every style. Ask to see a portfolio of recent works matching the desired window style for your project. Most studios gladly provide a color design for the window they propose prior to a contractual agreement. Remember, a studio which has difficulty conveying the window design on paper many have equal difficulty producing the design in glass. If they can’t draw it, they can’t build it.

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Types of Stained Glass: 

Our stock glass is available from many sources and varies greatly in price. Generally, glass is available in two categories: opalescent (milky white, very opaque) and translucent (nearly transparent). In order from the least expensive to most expensive:  

 

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  • Opalescent window glass – Usually a two to three color mix in a white milky glass
  • Machine rolled cathedral window glass – Mono-color glass with very uniform color distribution and thickness 
  • Mouth-blown window glass – Mono-color or multi-color glass with light and dark areas due to slight variations in glass thickness.  The handmade nature of this glass gives the glass character and adds depth and interest to the overall design. This grouping includes fine glass from Poland and Germany as well as some domestic sources.  

Within these three glass types, there are variations too numerous to recount.  Inquire as to the type of glass to be used on your project.  Fine mouth blown glass can cost 4 to 5 times more than opalescent and machine rolled cathedral glass.

 

Hand Painted Stained Glass Window Detail: 

Details such as faces and hands of window figures are hand-painted. Painting on glass is a labor-intensive effort.  When fired at 1200 degrees, the paint becomes permanently fused to the glass piece, but often, a piece of glass is painted and fired multiple times to add depth and detail.  Not all studios have in-house artist capable of painting on glass because, as with any art form, the style and talent of stained glass artists varies greatly.  Lynchburg Stained Glass is capable of producing painted window work in fine detail ranging from painted medallions to fully painted figurative scenes.  

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Stained Glass Window Design Intricacy: 

Basically, the smaller and more irregular the glass pieces, the more difficult the window is to glaze (assemble). Each piece of glass is hand-cut and individually glazed into the window with lead came. A quote based on providing a window with a specific number of pieces can be misleading if not accompanied by artwork. For example, consider two windows, each with 100 pieces of glass. The first design is predominately rectangular pieces with lots of straight lead lines and uniform borders. The second is a more irregular, figurative window where no two pieces of glass are the same size or shape.  As you might imagine, the second window is the more costly design. Always insist on seeing a design of the proposed window.

Hand painted detail and piece intricacy are the two factors most affecting the cost of stained glass. The fundamentals of constructing a stained glass window are independent of artistic content. Regardless of the cost of the window, the quality of the window is the same.  Every window is hand-assembled using lead came between the glass pieces, hand soldered on both sides, waterproofed on both sides, and reinforced with steel brace bars.   

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  • Does the studio offer aluminum frames and clear coverings to protect your stained glass investment? Lynchburg Stained Glass fabricates custom aluminum frames specifically designed for use with stained glass. We are capable of producing intricate frames requiring special bends.  Our frames are engineered to comply with building code requirements for wind load. Our recommended clear protective covering is laminated glass. Laminated glass is impact resistant and will not discolor with age. Avoid plastic covering products. They have a reputation of scratching and “yellowing” to the point that they obscure the stained glass.
  • Is the studio equipped to handle installations of large church projects requiring scaffold and/or lifts? Lynchburg Stained Glass maintains multiple in-house installation crews and provides scaffold and lift access as necessary.
  • Is the studio capable of producing the work in a timely manner to meet your construction schedule? Is the studio capable of providing a turn-key project including frames and protective covering? Lynchburg Stained Glass is a large full-service studio offering custom frames, protective covering, installation, and repair. Our large studio (approximately 30 artisans) is capable of producing large church projects in a timely manner.  We maintain a large glass inventory to facilitate production.
  • Does the stained glass window studio offer a warrantee? Lynchburg Stained Glass studio provides a 10-year warrantee covering material and workmanship.   
  • Can the stained glass window studio provide a certificate of insurance indicating liability coverage for the church while on site?  Lynchburg Stained Glass studio maintains liability insurance coverage for the purpose of protecting the church.

 

A Few Final Suggestions:

  • Ask for and check the stained glass window studio’s references on projects they have completed recently (within the past two or three years) for churches of the same size or larger than yours.
  • If possible, take a trip to tour the studio where the windows will be produced.
  • If cost is a factor and you plan to get prices from several different studios, make sure you understand exactly what each studio is providing for the cost quoted (especially concerning the intricacy and amount of hand painted work to be incorporated into the design).
  • Above all, make absolutely sure that you get what you want when purchasing stained glass… it will be there for a very long time.  Remember that you are purchasing a work of art, not an assembly line, machine-produced product.

Lynchburg Stained Glass Studio will gladly meet with your group:

We will gladly meet with your group to discuss options and present ideas for stained glass. Our artists welcome your input on religious theme, color and style. Translating your ideas to glass, we develop color artwork for your approval. Stained glass is a vibrant art form that speaks to your church and to the community. We welcome the opportunity to help convey your message in glass.

We can also repair religious stained glass church windows. Lynchburg Stained Glass studio offers a full range of restoration services ranging from a few minor glass repairs to complete re-lead restoration, the process by which the entire window is disassembled and re-crafted with new lead. We also offer protective storm covering to protect your stained glass investment. Our stained glass storm covering system uses impact resistant laminated glass set into a small profile aluminum frame.

 

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