Abrasion
A decorative technique frequently used on Flashed Glass to reveal underlying colors and control visual shading. The top layer of colored glass is physically worn away–often by sandblasting or grinding–to reveal a different color or clear glass beneath. This method allows for detailing, shading, or lettering without the use of paint. It is a form of Etching commonly found in intricate church window designs.
Acid-Etching
A decorative technique frequently used on Flashed Glass to reveal underlying colors and control visual shading. Acid is applied to selectively remove or thin the outer layer of colored glass. Acid-etching allows for the precise removal of flashed layers and can create finely detailed imagery, patterns, or lettering without paint. Acid-etching is a form of Etching used for subtle highlights and intricate ornamentation.
Antique Glass
High-quality, Hand-Blown Glass, prized for its rich color, subtle texture, and natural variations such as waves, air bubbles, and slight distortions. Made using traditional mouth-blown techniques, Antique Glass has been used in stained glass windows for centuries, particularly in churches, to achieve a luminous, vibrant effect when lit. Its optical irregularities add depth and movement to a design, making it a favored material for both restoration and new construction work that seeks a historic or handcrafted appearance.
Came
A material used in assembling Cut Glass. Came is a slender strip of lead, zinc, or another metal with a grooved cross-section, used to join the individual pieces of stained glass together. The glass pieces fit into the channels of the came, which is then soldered at the joints to create a stable structural framework. Came is commonly classified as “H-channel” or “U-channel” depending on their shape, and are available with a flat or rounded face. Lead came is the most common and traditional in church stained glass, and frequently contributes to the visual outlines that define figures and shapes in the design.
Came Knife
Also known as a Lead Knife. A specialized tool used in stained glass work to cut lead Came accurately and cleanly. Designed with a short, rigid blade, the Came knife allows for precise trimming to fit around pieces of Cut Glass. In church window restoration and construction, this tool ensures tight joints and proper alignment, contributing to the structural integrity and visual clarity of the finished Panel.
Cartoon
A full-scale drawing of a stained glass window design, used as a precise guide for cutting glass and assembling the final composition. The cartoon includes all details of the artwork, including color placement, lead lines, and painted features. In church stained glass, cartoons serve as both a working template for artisans and an archival record of the window’s original design, especially important for restoration and historical documentation.
Cartouche
A decorative frame or scroll-like design, often oval or rectangular with ornamental flourishes, used to enclose text, emblems, or symbolic imagery in stained glass windows. In church settings, cartouches frequently contain scripture passages, donor names, dedications, or heraldic symbols, and are integrated into the overall design as both visual and narrative elements. Their elegant borders help distinguish the enclosed content and lend formality and emphasis within the larger Panel.
Cathedral Glass
A type of Rolled Sheet Glass that is single-colored, transparent, and typically Machine-Rolled into thin sheets. Cathedral glass often features a slight texture that diffuses light while still allowing it to pass through clearly. Commonly used for backgrounds, borders, and decorative accents, it is valued for its vibrant color and affordability compared to Hand-Blown Glass.
Cement
In stained glass work, cement is a specialized waterproofing compound used to seal and strengthen Leaded or Copper Foiled Panels by being worked into the gaps between the glass and the metal framework. Once applied, it hardens to secure the Cut Glass pieces, provide rigidity, and protect against Storms, Condensation, and debris. In traditional church windows, cement is essential for durability. In Dalle de Verre construction, Cement may also refer to the concrete matrix into which thick glass slabs are embedded, serving as both a structural frame and a design element.
Clerestory
The upper section of a church wall, typically above the nave arcade and below the roofline, often containing a row of windows that admit light into the central interior space. In stained glass design, clerestory windows are often smaller and more repetitive than those in lower levels, and may feature geometric patterns, Quarries, or simplified iconography. Clerestory stained glass serves both a practical and symbolic purpose–illuminating the space from above.
Condensation Control
The methods and materials used to prevent the ingress and buildup of moisture in, on, or around stained glass windows. Condensation can lead to corrosion, paint loss, and structural deterioration. Condensation Control often involves proper ventilation, protective Glazing systems, and the use of breathable materials that allow air circulation while shielding the window from extreme temperatures. Effective Condensation Control is essential for preserving the integrity and longevity of historic and modern stained glass installations.
Copper Foil
Also known as the Tiffany Method. A method of assembling Cut Glass in which the edges of each piece of glass are wrapped in a thin adhesive-backed copper tape. The pieces are then positioned together and soldered along the seams to create a unified panel. Popularized by Louis Comfort Tiffany in the late 19th century, Copper Foil allows for more intricate designs and finer detail than traditional lead Came, and is sometimes used smaller panels and interior designs.
Crown Glass
A traditional type of Hand-Blown Glass made by spinning a molten glass bubble into a flat, circular sheet. This process creates a distinctive “bullseye” pattern at the center, at the point where the glass was attached to the blowing rod. Crown Glass is common in historic church windows and is prized for its clarity, subtle surface variations, and shimmering optical effects that enhance the play of light.
Cut Glass
Glass that has been shaped and trimmed to specific sizes and patterns using specialized tools such as glass cutters or Grozing Pliers. Each piece is carefully cut to fit a section of the overall design, like a puzzle piece. Cut glass forms the individual segments of a scene. Those segments are joined together with Came or Copper Foil to complete the Panel.
Cylinder Glass
A traditional type of Hand-Blown Glass made by forming a large cylindrical bubble of molten glass, which is then cut open, reheated, and flattened into a sheet. Known for its slight waviness, air bubbles, and rich color depth, the subtle imperfections of Cylinder Glass provide a vibrant, lively quality as light passes through.
Dalle de Verre
Also called Slab Glass. A modern technique for assembling stained glass that uses thick slabs of colored glass, typically an inch or more, cut or chipped into shape and set into a matrix of Cement or Epoxy resin. French for “slab glass,” Dalle de Verre creates bold, jewel-like effects with intense color and texture. Introduced in the mid-20th century, it is common in contemporary church architecture and design where it brings a dramatic, sculptural quality to worship spaces.
Enameling
A decorative technique used to create Painted Glass where finely ground colored glass (Enamel) is mixed with a liquid medium and brushed or sprayed onto the surface of the glass. The piece is then Kiln-Fired to fuse the enamel permanently. Enameling is frequently used in church windows to create facial features, garment details, and inscriptions. It provides vivid colors and intricate imagery that are not possible with Cut Glass alone.
Epoxy
A material used in assembling stained glass Panels. Epoxy is a strong, two-part adhesive resin used in some modern stained glass construction methods, especially in Dalle de Verre windows. In this technique, thick chunks of colored glass are set into molds and bonded together with Epoxy instead of traditional Lead or Cement. While not found in historic stained glass, Epoxy allows for bold, structural designs often found in contemporary church architecture and design.
Etching
A decorative technique frequently used on Flashed Glass to reveal underlying colors and control visual shading. Etching can be accomplished mechanically, using Abrasion, or chemically, with Acid-Etching. This method allows for detailing, shading, or lettering without the use of paint. It is commonly found in intricate church window designs.
Flashed Glass
A type of stained glass made by fusing a thin layer of colored glass onto a base layer of clear or differently colored glass during the blowing process. This layered construction allows artisans to use Etching to selectively remove the top layer to reveal the base layer underneath. Flashed Glass enables detailed shading, intricate imagery, and decorative effects without relying on paint.
Fusing
A modern decorative technique in which multiple layers or pieces of glass are arranged together and then melted in a Kiln until they fuse into a single, unified piece. This method allows for rich color blending, textural effects, and complex shapes that aren’t achievable with traditional Cut Glass. While much less common in historic church windows, fusing is frequently used in contemporary churches to create expressive, painterly designs. Fusing is different from Plating in that the layers are permanently melted together.
Glazing
The process of installing glass into a window frame including the securing, sealing, and supporting of the glass within its architectural setting. In stained glass, Glazing refers both to the final step of setting completed Panels into their Sash or Tracery and to the broader system of protective or decorative glass layers. In church windows, Glazing may involve multiple components such as lead Came, Cement, and exterior-mounted protective windows.
Grisaille
A decorative technique used to create Painted Glass, Grisaille is the application of monochromatic shades of color, typically gray or brown, made from powdered glass mixed with a liquid medium. Grisaille is a type of Enameling. The enamel is applied with brushes and then Kiln-Fired. This technique is used to create depth, lines, shading, and texture—especially in faces, fabrics, and architectural elements. It enhances the depth of colored glass without relying on additional coloration.
Grozing
A technique used in stained glass work to shape or refine the edges of Cut Glass pieces by nibbling away small fragments of glass. Grozing is typically done with Grozing Pliers, allowing artisans to achieve precise fits and smooth curves that cannot be made with a standard glass cutter alone. This process is essential for ensuring that each piece of a Pane fits accurately within the design and aligns properly with the lead Came or Copper Foil.
Grozing Pliers
A hand tool used in stained glass work to shape, trim, and refine the edges of Cut Glass pieces. One jaw is flat while the other is curved or serrated, allowing the user to nibble away small bits of glass–a process known as Grozing. Grozing Pliers are essential for achieving precise fits, especially in curved or intricate areas of a stained glass window design, where exact alignment within the Came or Foil is critical to the integrity of the design.
Hammered Glass
A decorative technique used to create Textured Glass by adding small, irregular hammer marks. This texture diffuses light softly while maintaining partial transparency, adding depth and visual interest to church windows. It is often used to create background effects, privacy, or a sense of movement, enhancing the overall richness of a design without distracting from focal imagery.
Hand-Blown Glass
A traditional method for creating glass by inflating molten glass into a bubble using a blowpipe, then shaping it by hand through spinning, stretching, or molding. Hand-Blown Glass can provide rich color and unique character due to natural variations such as waves, bubbles, and irregular textures, which give stained glass windows a lively, luminous quality. In church windows, Crown Glass and Cylinder Glass are typically hand-blown.
Hand-Blown Sheet Glass
A traditional method for creating glass by inflating molten glass into a bubble using a blowpipe, shaping it into a cylinder or disk, and then cutting and flattening it into thin sheets. Hand-Blown Sheet Glass is known for its rich, vibrant colors and natural surface variations, such as subtle ripples and air bubbles, which enhance light transmission and visual texture.
Hand-Rolled Sheet Glass
A traditional method for creating glass by pouring molten glass onto a flat surface and rolling it into a sheet using a metal cylinder. Hand-Rolled Sheet Glass allows for greater control over color blending, texture, and thickness. It often features rich swirls, streaks, or embedded textures, making it popular in both traditional and contemporary church windows for adding depth, movement, and visual interest to a design.
Kiln Firing
The process of heating stained glass in a controlled kiln to permanently fuse painted details, Enamels, Silver Stain, or Fused glass elements to the surface. Essential for creating Painted Glass, Kiln Firing transforms applied pigments into durable, integrated features of the glass. This process ensures that artistic details remain stable over time, resistant to Condensation and environmental wear.
Lancet
A tall, narrow window with a pointed arch at the top, commonly found in Gothic church architecture. Lancet windows are often used singly or grouped in sets, sometimes beneath larger Rose or Tracery Windows. In stained glass, Lancets typically feature vertical compositions such as saints, biblical scenes, or symbolic motifs, taking advantage of the elongated format to draw the eye upward.
Lead Knife
Also known as a Came Knife. A specialized tool used in stained glass work to cut lead Came accurately and cleanly. Designed with a short, rigid blade, the Came Knife allows for precise trimming to fit around pieces of Cut Glass. In church window restoration and construction, this tool ensures tight joints and proper alignment, contributing to the structural integrity and visual clarity of the finished Panel.
Leading
A method of assembling Cut Glass by fitting pieces into strips of lead called Cames, which have a grooved cross-section to hold the glass securely. The joints are then soldered and the panel is often Cemented for strength and Weatherproofing. Leading creates visible lines that outline and define the design, serving as both structural and artistic functions.
Leadlight
A glass Panel made from small pieces of clear, lightly tinted, or simply patterned glass joined together with lead Cames, typically forming geometric or repetitive designs. Unlike fully pictorial stained glass, leadlights often lack painted imagery and are more common in domestic and civil buildings. In church architecture, leadlight windows are often found in side chapels, Clerestory openings, or ancillary buildings, providing decorative Glazing with a more understated visual effect.
Machine-Rolled Sheet Glass
A type of glass produced by mechanically rolling molten glass into flat sheets. Machine-Rolled Sheet Glass provides consistent thickness and texture, and it is more affordable and more widely available than Hand-Blown Glass or Hand-Rolled Sheet Glass. It is often used in church windows for background colors, borders, and geometric patterns. Machine-Rolled Sheet Glass is available in a wide range of colors and surface textures, though it typically lacks the subtle variations and imperfections found in handmade glass.
Mullion
A vertical structural element that divides adjacent window openings within a larger window frame. In churches, Mullions are typically made of stone or wood and serve both architectural and visual functions–supporting the wall above while segmenting stained glass Panels into manageable sections. Mullions are often combined with horizontal elements called Transoms and may be integrated into Tracery, helping to organize complex window designs and enhance the overall aesthetic of the window composition.
Muntin
A slender strip of wood or metal that separates and holds individual panes of glass within a window. In stained glass, Muntins are more common in domestic and civil settings than in large-scale church windows. Unlike Mullions, which are structural elements dividing whole window openings, Muntins divide panes and Panels within a single Sash and are typically associated with non-leaded Glazing systems. In church architecture, Muntins may be found in Clerestory or auxiliary windows where simpler construction is used.
Opalescent Glass
A type of Rolled Sheet Glass made by combining minerals into the molten glass. Opalescent Glass is characterized by its milky, translucent appearance and swirling mixtures of colors within a single sheet. It diffuses light rather than allowing it to pass through clearly, creating a soft, glowing effect. Popularized in American church windows, especially in Tiffany-style designs, it allows for more painterly imagery and greater detail without relying on extensive painting or etching.
Painted Glass
A decorative technique in which vitreous paints made from powdered glass and metal oxides are applied to the surface of glass and then Kiln-Fired to fuse the design permanently. Painted Glass allows for detailed features such as facial expressions, textural details, lettering, and shading. It is frequently used to bring figures and scenes to life with fine detail and subtle realism. Grisaille, Enameling, and Silver Stain are types of Painted Glass.
Panel
A single, self-contained section of a stained glass window. A panel can be composed of a single sheet of glass or multiple pieces of Cut Glass joined together by Cames, Copper Foil, Epoxy, or another method. Panels are the basic building blocks of larger stained glass installations and are often assembled in a wooden or metal Sash, which is then mounted with a metal or stone Tracery. A panel can depict a distinct scene, figure, or pattern, and several panels are often combined to form a complete narrative or decorative composition.
Plating
A technique used in stained glass work in which two or more layers of glass are stacked and held together to achieve deeper color, enhanced texture, or special visual effects. This layering can intensify light transmission, create shading, or correct tonal imbalances in a design. In church windows, Plating is often used to add richness and dimension to figures, backgrounds, or symbolic elements, especially when a single piece of glass cannot achieve the desired visual result. Plating is different from Fusing in that the layers are not permanently melted together.
Pot Metal Glass
A type of stained glass colored by adding metallic oxides directly into the molten glass while it is still “in the pot,” resulting in rich, permanent color throughout the entire thickness of the glass. Pot Metal Glass has been used in church windows since medieval times due to its deep hues and durability. Unlike Flashed Glass, its color is not layered but fully integrated, making it ideal for vibrant, light-filled designs that stand the test of time. Hand-Blown Sheet Glass and Rolled Sheet Glass are often Pot Metal Glass.
Quarry
A small, usually diamond-, square-, or lozenge-shaped piece of glass used in repeating patterns to form decorative elements or whole windows. Quarries are often clear, lightly tinted, or patterned, and may feature painted details such as floral motifs, heraldic symbols, or inscriptions. In church artwork, quarries are commonly found in domestic-style windows, borders, or less formal architectural settings. They provide a rhythmic, ornamental effect that contrasts with more pictorial Panels.
Quatrefoil
A decorative architectural shape consisting of four rounded lobes or leaf-like forms arranged symmetrically, resembling a four-petaled flower or clover. Common in Gothic Tracery, the Quatrefoil is often used to frame small stained glass Panels or serve as a window opening itself. In church architecture and design, Quatrefoils often contain symbolic or ornamental imagery, contributing both structural support and visual richness to the overall window composition.
Rebar
Also called Saddle Bar, Support Bar, or Tie Bar. Short for “reinforcing bar,” Rebar in stained glass refers to metal support rods–typically made of steel, wrought iron, or brass–installed behind or across a stained glass Panel to provide structural reinforcement. These bars are tied to the lead Cames with wire and help prevent Sagging, bowing, or distortion over time, especially in large or vertically-oriented church windows like Lancets. While not always visible from the front, Rebar plays a crucial role in the long-term stability and preservation of some stained glass installations.
Rippled Glass
A type of Textured Glass with a wavy surface that can mimic the look of flowing water. Created during the rolling process, the wavy texture distorts light and adds movement and depth to a design. Rippled Glass is often used to suggest elements like water, flowing fabric, or radiance, enhancing the dynamic visual effect of a piece while still allowing colored light to pass through.
Rolled Sheet Glass
A type of stained glass made by pouring molten glass onto a flat surface and using rollers to form a sheet of uniform thickness. This method can be done by Hand or Machine, producing glass in a wide range of colors, textures, and translucencies. Rolled Sheet Glass is common in traditional and modern church windows and is valued for its consistency and versatility, serving as a base material for backgrounds, decorative elements, and textured effect. Cathedral Glass and Opalescent Glass are types of Rolled Sheet Glass.
Rose Window
A large, circular stained glass window, often found in the façades or transepts of Gothic churches, featuring intricate Tracery radiating outward in a symmetrical, floral-like pattern. Rose Windows are typically composed of multiple Panels arranged around a central motif, often depicting scenes from the Last Judgement, the Virgin Mary, or other theological themes. Renowned for their grandeur and symbolic geometry, Rose Windows serve as focal points of both artistic and spiritual expression in church architecture and design.
Saddle Bar
Also called Rebar, Support Bar, or Tie Bar. Most commonly used in the U.K., Saddle Bars in stained glass refers to metal support rods–typically made of steel, wrought iron, or brass–installed behind or across a stained glass Panel to provide structural reinforcement. These bars are tied to the lead Cames with wire and help prevent Sagging, bowing, or distortion over time, especially in large or vertically-oriented church windows like Lancets. While not always visible from the front, Saddle Bars play a crucial role in the long-term stability and preservation of some stained glass installations.
Sagging
Sagging is a structural issue in stained glass windows where the panel begins to bow or bulge due to age, gravity, or weakened support. Sagging can occur when lead Cames stretch over time, solder joints fail, or when the window lacks adequate structural reinforcement. Sagging not only distorts the appearance of the design but can also lead to cracking or glass loss if not addressed and maintained through preservation and restoration.
Sash
A fixed or movable wooden or metal frame that holds a stained glass Panel within a window opening. In church architecture, the Sash supports and secures the stained glass, often fitting within a larger stone, wood, or metal Tracery. While some Sashes are part of operable windows, most stained glass sashes in churches are stationary and designed to provide structural stability while protecting the artwork from the elements.
Seedy Glass
A type of Textured Glass with small air bubbles or “seeds” intentionally trapped within the sheet during the glass manufacturing process. The bubbles give the glass a distinctive, Antique appearance and gently diffuse light, adding texture and visual interest. Seedy Glass is often used to create a historic or handcrafted aesthetic. It is especially effective in backgrounds, borders, and other areas where a subtle, aged look is desired.
Silver Stain
A decorative technique used to create Painted Glass that uses a solution of silver nitrate applied to the surface of clear or lightly-colored glass. When fired in a Kiln, the silver compound penetrates the glass and produces a transparent yellow to amber stain, depending on the concentration and firing conditions. Introduced in the 14th century, Silver Stain became a key feature in church stained glass, often used for halos, hair, architectural details, and golden light effects.
Slab Glass
Also called Dalle de Verre. A modern technique for assembling stained glass that uses thick slabs of colored glass, typically an inch or more, cut or chipped into shape and set into a matrix of Cement or Epoxy resin. Slab Glass creates bold, jewel-like effects with intense color and texture. Introduced in the mid-20th century, it is common in contemporary church architecture and design where it brings a dramatic, sculptural quality to worship spaces.
Slumping
A modern decorative technique where glass is heated in a Kiln until it softens and gradually conforms to the shape of a mold beneath it. Slumping allows stained glass to take on three-dimensional forms, such as curves or textured reliefs. While not commonly used in traditional church windows, slumping is sometimes employed in contemporary church art to create sculptural effects or architectural elements that interact with light in unique ways.
Spandrel
The triangular or curved space between the top of an arch and the rectangular frame surrounding it, often found adjacent to Lancet windows or beneath larger Tracery elements in church architecture. In stained glass design, Spandrels may be filled with decorative glass, painted motifs, or ornamental patterns that visually connect adjoining elements. Though not always the main focus, Spandrels play an important role in completing the composition and harmonizing the architectural layout of a stained glass installation.
Storm Damage Prevention
Protective measures taken to shield stained glass windows from damage caused by high winds, hail, flying debris, and other severe weather events. In church settings, this often includes the installation of protective Glazing, such as exterior-mounted clear glass or polycarbonate windows, as well as ensuring proper anchoring, sealing, and structural reinforcement of the window frame. Effective storm damage prevention helps preserve the integrity, safety, and longevity of stained glass windows, especially in regions prone to extreme weather.
Support Bar
Also called Rebar, Saddle Bar, or Tie Bar. Support Bar in stained glass refers to metal support rods–typically made of steel, wrought iron, or brass–installed behind or across a stained glass Panel to provide structural reinforcement. These bars are tied to the lead Cames with wire and help prevent Sagging, bowing, or distortion over time, especially in large or vertically-oriented church windows like Lancets. While not always visible from the front, Support Bars play a crucial role in the long-term stability and preservation of some stained glass installations.
Textured Glass
A type of glass with a deliberately patterned or uneven surface that scatters and diffuses light. Created during the rolling or molding process, textures can include subtle Ripples, pronounced Hammer marks, Seedy bubbles, and granite swirls. In church art, Textured Glass is used to add depth, visual interest, and a sense of movement, while also softening glare and enhancing the interplay of light and color.
Thermal Protection
Measures taken to shield stained glass windows from damage caused by extreme or fluctuating temperatures. In church settings, Thermal Protection helps prevent issues such as glass cracking, Lead fatigue, and Paint deterioration by managing heat buildup and reducing thermal stress. This often includes the use of vented protective Glazing, insulated installations, or climate control within the building. Effective Thermal Protection is essential for preserving the structural integrity and visual quality of stained glass over time.
Tie Bar
Also called Rebar, Saddle Bar, or Support Bar. Tie Bars in stained glass refers to metal support rods–typically made of steel, wrought iron, or brass–installed behind or across a stained glass Panel to provide structural reinforcement. These bars are tied to the lead Cames with wire and help prevent Sagging, bowing, or distortion over time, especially in large or vertically-oriented church windows like Lancets. While not always visible from the front, Tie Bars play a crucial role in the long-term stability and preservation of some stained glass installations.
Tiffany Method
Also known as Copper Foil. A method of assembling Cut Glass in which the edges of each piece of glass are wrapped in a thin adhesive-backed copper tape. The pieces are then positioned together and soldered along the seams to create a unified panel. Popularized by Louis Comfort Tiffany in the late 19th century, the Tiffany Method allows for more intricate designs and finer detail than traditional lead Came, and is sometimes used smaller panels and interior designs.
Tracery
The ornamental framework that supports and divides stained glass Panels within a window opening. Tracery can be simple or highly intricate, forming patterns such as Trefoils, Quatrefoils, and flowing curves that enhance the aesthetic and structural integrity of a window. It serves both a decorative and functional role, helping to distribute the weight of the glass, controlling Sagging, and contributing to the overall architectural harmony the piece.
Tracery Window
A stained glass window that incorporates Tracery–the ornamental framework dividing and supporting the glass into decorative patterns, often featuring Trefoils, Quatrefoils, or flowing curves. Common in Gothic architecture, Tracery Windows combine structural function with elaborate design, allowing for complex compositions made up of multiple Panels. In church settings, Tracery Windows often serve as focal points, showcasing biblical scenes, saints, or symbolic imagery within a richly articulated architectural frame.
Transom
A horizontal architectural element that separates a window from the structure above it, or divides sections within a larger design. In church settings, a Transom may act as a support for upper Panels or as a visual break between different scenes or designs. Often combined with Mullions in complex window layouts, Transoms help organize vertical space and provide additional stability, especially in tall or multi-part window compositions.
Trefoil
A decorative architectural shape consisting of three rounded lobes or leaf-like forms arranged symmetrically, resembling a three-petaled flower or clover. Common in Gothic Tracery, the Trefoil is often used to frame larger stained glass Panels or serve as a window opening itself. In church architecture and design, Trefoils often contain symbolic or ornamental imagery, and are used to convey the theological idea of the Holy Trinity. They contribute both structural support and visual richness to the overall window composition.