The Historic
Dimension Series
A student publication series by the UNCG Department of Interior Architecture
Brightening the 20th Century:
The Influence of Prismatic Glass
by Abby Gentry Spring 2011
Walking down Elm
Street in Greensboro,
North Carolina, one can
view many phases in storefront transom
designs beginning in the late nineteenth
and early twentieth century. In fact, many
twentieth century Main Streets across the
U.S. illustrate the phases in commercial
storefronts. Storefronts have been a very
significant part of commercial architecture
history. Commercial storefronts are particu-larly
valuable because they continue to play
a critical role in advertising and increasing
business sales (Jandl, 1982).
In the 1870s, a new advancement in store-front
design occurred. During this time
period, commercial buildings began using
large display windows on the ground floor
(Gelbloom, 1978). Previously, storefronts
resembled residential buildings with resi-dentially
scaled windows and doors. But
with the use of display windows, the desire
to have storefronts that appeared light and
open distinguished the commercial building
from the residential building.
Two technological innovations occurred
during the 1800s that led to the evolution
of storefront designs. These technological
advances included the development of cast
iron and new advances that led to the pro-duction
of large panes of glass. By the late
nineteenth century, storefronts consisted of
a recessed entryway with two display win-dows
on either side. By the early twentieth
century, the use of transom lights with pris-matic
glass panes became prevalent. These
transom lights sometimes incorporated
moveable vents to increase air circulation.
Storefront Limitations and Designs
Main Street storefronts are one of the best
and most abundant examples of the utiliza-tion
of prismatic glass in America. Store-fronts
are also the best location to find
remaining prismatic glass. Glass used in
storefronts has seen several evolutions.
Windows in storefronts began by resembling
residential windows then cylinder and bent
glass became popular. After cylinder and
bent glass, there was plate glass and pris-matic
glass (Marinelli, 1988). Prismatic glass
allowed for light to reach spaces of interiors
that previously could not be lit. Not only
did this allow for more business employ-ment
and use, but it also allowed stores to
have longer business hours, which made
them more profitable.
The use of prismatic glass in storefronts had
a huge impact on the design and appearance
of commercial buildings. In the nineteenth
century, no interior point could be more
than 25 feet from a window or there would
be an inadequate amount of daylighting.
The measurement of 25 feet applied not only
for lighting needs but for ventilation needs
as well. The desire for plentiful daylighting
and ventilation restricted the configurations
of architecture during this time. Buildings
that were designed resembled alphabet
characters of L, U, and E in plan. These
shapes were used in order to maximize ex-posure
to light as well as maximize ventila-tion.
Before the widespread use of electric-
Prismatic
glass was
developed to
increase the
amount of
light entering
a room
without
adding more
windows.
UNCG The Historic Dimension Series: 2
Fig. 3: The Luxfer Prism Company patent. In Olin H.
Basquin’s patent, he writes that this is a patent for a new
and improved design for window-glass.
ity, the new invention of prismatic glass allowed new
ways to light buildings in the late nineteenth century.
The focus on providing the most amount of natural light
possible was extremely important because natural light
was one of the only ways a building could be lit. Archi-tects
and contractors were very focused on daylighting
due to this necessity.
Daylighting Needs & A New Invention
Daylighting remains an influence in architecture because
it provides a free illumination source and affects people
and how they work. Daylighting can affect people in
positive and negative ways. Researchers studied poor
exposure to natural lighting compared with abundant
exposure of natural lighting. The study showed that
students and workers perform better when natural light
is more abundant (Blatner, 1948). The affects of natural
light, the direct influence of saving money, and the need
to light space, drove inventors of the nineteenth cen-tury
to develop the idea of prismatic glass. While other
types of glass allowed rays to pass directly through the
pane, inventors developed prismatic glass to increase
the amount of light entering a room without adding
more windows. As seen in Figure 2, prismatic glass was
achieved through texturizing, which increased the depth
that refracted light reached. Careful consideration was
given to the texture of the glass in order to reach the
desired amount of lighting in a building. The light-ing
method was ideal for commercial architecture, and
saved room and money spent on electricity, as well as lit
basements with natural light.
Prismatically shaped glass can be traced to the early
eighteenth century. It was first used to direct light
into the interiors of ships. By the second half of the
nineteenth century, prismatic glass was being used for
skylights in pavements to allow light in the basements
of commercial buildings (Jester, 1995). The prismatic
skylights would bounce sunlight underneath buildings
where, before prismatic glass’s invention, natural light-ing
could not reach.
Prismatic glass was widely used in pre-electric commer-cial
buildings (Jester, 1995). Prismatic glass transoms
were introduced to the architecture of commercial build-ings
in the 1890s as a way to direct daylight to the rear
of a building. By expanding the amounts of space that
could receive light, businesses could expand, thereby
increasing revenue. Prismatic glass was also used in the
United States as an energy-saving mechanism at the turn
of the twentieth century.
Even though prismatic glass was used in ships and
commercial buildings before the late nineteenth century,
the real breakthrough came in 1897, when “a group of
Chicago businessmen joined forces with the inventor,
James Pennycuick, to found the Luxfer Prism Company”
(Prismatishes Glass = Prismatic Glass, 1995, p. 24).
Chicago’s Luxfer Prism Company was the most influ-ential
manufacturer of prismatic glass. The company
worked to develop a very specific formula to calculate
individual prescriptions for lighting buildings. The
formula was very similar to how optometrists prescribed
certain lenses for patients (Jester, 1995). The calculations
were used to find the right type of prism, combination,
and placement for each building. For some architects
who thought the calculations were too complicated, the
Luxfer Prism Company suggested an average textured
Fig. 2: Detail photograph of a prismatic glass tile. Cour-tesy,
National Park Service, Chad Randl
UNCG The Historic Dimension Series: 3
Fig. 4: The Luxfer Prism Company patent. In William S.
MacHarg’s design, he uses both sides of the glass for
parallel prisms and grooves.
Fig. 5: The Luxfer Prism Company patent. Frank Lloyd
Wright’s design illustrates the more intricate of the pat-ents
that The Luxfer Company submitted.
angle of 57 degrees. In 1897, the Luxfer Prism Company
had submitted 162 patents for designs, frames, and ma-chinery
to create their prismatic glass. Figures 3 and 4
are from the Luxfer Prism Company. The company was
such a success that within one year after opening, they
had already installed prismatic glass into 296 buildings.
By 1906, the number of buildings with the Luxfer Prism
Company’s prismatic glass had reached to over 12,000.
As Luxfer and their prismatic glass gained popularity,
many competitors developed. By 1905, some of Luxfer’s
competitors included Luminous Prism, American 3-Way
Prism, Searchlight Prism, Daylight Prism, and Solar
Prism, but Luxfer Prism Company remained the most
successful seller.
Manufacturing, Designing and Installing
The development of prismatic glass was a unique pro-cess.
The glass was pressed into iron molds to produce
the textures in the glass. In order to create the various
rib forms, manufacturers created and used special dies.
The exterior prisms on the glass would catch near verti-cal
sunrays and refract them horizontally into the store
or building while the interior side of the glass would
collect ambient light and filter it throughout the room
(Marinelli, 1988). The Luxfer Prism Company began by
developing small 10x10 cm glass tiles that were 3 mm
thick (Prismatishes Glass = Prismatic Glass, 1995). The
glass originally could not be created in larger sheets
because they tended to crack. The small tiles would then
be assembled in a frame of 60-120 cm high. The frames
would then be installed into the building.
Several architects used prismatic glass while some even
helped design some of the glass textures. Several of
the well-known architects to use the material included
Frank Lloyd Wright, William Le Baron Jenney, and Louis
Sullivan. Frank Lloyd Wright was one of the architects
that worked with the Luxfer Prism Company to create
special designs. He designed 41 prismatic glass textures.
Figure 5 is Wright’s most famous design out of the 41.
Prismatic glass tile had ridges and other raised patterns
on the inside surface that directed sunlight. The tiles
were joined together using zinc or lead. The original
color of the glass was clear, but after World War I, man-ganese
was added which eventually made the glass turn
green. Also, after years and years of exposure, UV rays
could make the manganese turn a purple color.
“Prismatic glass was the most sophisticated and com-plex
development among the many attempts in the
last decades of the nineteenth century to bring more
daylight into the dark interiors of factories and densely
built urban centers” (Neumann, 1995, p. 24). The Luxfer
UNCG The Historic Dimension Series: 4
Company described the glass as not only a way to light
up a dark space, but a design and safety feature as well.
The glass could increase the amount of light in a room
between 5 to 50 times that of ordinary glass, but its
success depended on the specific circumstances of the
building (Jester, 1995). The product was a great success
and was introduced to almost every Main Street across
the United States, including Greensboro. Figures 6 and 7
are photographs of prismatic glass utilized in storefronts
along Greensboro’s South Elm Street.
The invention of prismatic glass was a major break-through
for daylighting but it did have some drawbacks,
including its expense and difficulty to keep clean. In
1903, plate glass cost five cents per square foot while
prismatic glass cost up to fifty cents per square foot.
Business owners were required to weigh the options of
the cost of installation to the proposed increase in sales
after the installation. Due to the success of the product,
it is not difficult to determine which side business own-ers
leaned towards.
Prismatic glass was commonly installed in three ways, in
a window sash, separate frames in front of existing win-dows,
or as a transom. Towards the waning of the glass
as a popular building material, prismatic glass was even
used for glass blocks. The introduction of prismatic
glass changed the architecture of commercial buildings
of the early twentieth century. The new glass was usu-ally
placed at a prominent position on the storefronts of
commercial buildings as seen in the historic 1920s pho-tograph
of Figure 8. It was placed in the upper section
of the store’s first and/or second floors. The placement
of the prismatic glass windows influenced floor plan de-signs
when existing light shafts could be converted into
floor space once the prismatic glass was installed. Along
with storefronts and floor plans, ceiling heights could be
reduced because light could reach farther into spaces,
which eliminated the need for high ceilings. Prismatic
glass was most frequently used in commercial build-ings,
but residences, schools, and hospitals of the early
twentieth century would sometimes install the material
as well (Jester, 1995).
Prismatic Glass Block
After the development of prismatic glass, another ad-vancement
for daylighting occurred. This advancement
was in the utilization of prismatic glass for developing
prismatic glass blocks. An example is illustrated in
Figure 11. In the late 1930s, the arrival of light-diffusing
glass block created a series of improvements in daylight-ing
(Boyd, 1951). The first prismatic glass blocks were
manufactured by the Owens-Illinois Glass Company
in 1937. Once developed, scientists began studying the
glass block’s potential affects on daylighting. Around
the same time that the prismatic glass block was manu-factured,
scientists had begun to study the effects of
natural light on human activity. Before prismatic glass,
daylighting was almost entirely achieved by the use
of nonfunctional light-transmitting materials like clear
sheet glass. Unlike prismatic glass, clear sheet glass does
not control the direction or the amount of sunlight that is
coming into a space.
The prismatic glass block was developed in order to
maximize the amount of daylight. The four surfaces
allowed “light-controlling designs [to] be impressed in
contrast to the two surfaces available in the case of sheet
glass” (Boyd, 1951, p. 5). The developers of the pris-matic
glass block believed that the increased number of
planes in the glass block on which prismatic glass could
be placed, would allow for an increase in the amount
of daylighting available for a building. By the time of
development, the making of prismatic glass had come
down to a science. Scientists could mathematically cal-
Fig. 7: South Elm Street, Greensboro, North Carolina.
Detailed photograph of a prismatic glass transom utiliz-ing
different colors and textures.
Fig. 6: South Elm Street, Greensboro, North Carolina.
Storefront with prismatic glass transoms.
UNCG The Historic Dimension Series: 5
culate the average amount of lighting available with the
angle of the sun to determine the potential foot-candles
the material could produce. In order to achieve the most
illumination possible, manufacturers suggested reflec-tive
surfaces positioned on the ceiling and upper por-tions
of the walls because the glass block would direct
most of the light to these surfaces first. If the upper
portions of the room were reflective, light would hit
those surfaces and then bounce off to other areas of the
room. The use of prismatic glass blocks was seen in both
institutional and commercial settings.
Fading Away
Unless there are remnants of the original glass, prismatic
glass has largely been abandoned. By the 1930s, the de-mand
for electricity caused the prismatic glass transoms
to become obsolete (Chad, 2001). The most abundant
use of prismatic transoms was for display windows and
doorways of Main Street buildings. Prismatic glass saw
a renewed interest during the 1940s and 1950s. Today,
many original prismatic transoms have been covered or
replaced with other glasses. But as the interest in sus-tainability
increases, scientists are beginning to study the
ways prismatic glass can be utilized again.
Neither the Luxfer Prism Company nor any of their
competitors are still in business, but the look and use
of prismatic glass remains appropriate for the 21st
century. After the 1930s, when prismatic glass became
obsolete, many storefronts’ prismatic glass was either
covered with signboards or new facades, or covered in
paint (Marinelli, 1988). If the restoration of prismatic
glass to a storefront is desired, it could be as easy as
removing panels that conceal it. If the glass has been
removed but the desire for prismatic glass remains, there
are three options to choose from: custom cast new glass
tiles, used textured glass, or salvaged historic material.
The National Park Service lists four possible sources to
replace the prismatic glass. These include: The Archi-tectural
Glass, Inc., of Beacon, New York, which can cast
new prismatic tiles using historic steel molds purchased
from an original manufacturer; the Rambusch Studios
of Jersey City, New Jersey, who sell original prismatic
tiles acquired from the Canadian Luxfer Prism Company
(their collection offers several patterns); Pilkington/
Libbey-Owens-Ford in Toledo, Ohio, has a 1/4” reeded
glass that has been used as a substitute for historic
prismatic tiles; and the Hollander Glass Central, Inc., of
Downers Grove, Illinois, that manufactures cross-reeded
and double reeded textured glass that resembles pris-matic
tile patterns (Chad, 2001).
Conclusion
The development of prismatic glass had a profound
impact on commercial storefronts in the early twentieth
century. Most commonly used in transoms located in
the upper portions of the facade, prismatic glass influ-enced
the design and appearance of Main Streets across
America. The utilization of prismatic glass can be seen
locally on South Elm Street in Greensboro, North Caro-lina.
Since prismatic tiles are difficult to locate, the best option
for existing prismatic glass in historic buildings is to
maintain them. Challenges may arise as prismatic glass
panels can bulge over time, which is caused by the fail-ing
of the lead cames. The metal can be repaired with-out
damaging the glass tiles and therefore the prismatic
glass transoms should always be kept in place. If proper
maintenance is given, historic prismatic glass can be
upheld and the character of the building can be main-
Fig. 9: Opera House in Delphi, Indiana, undergoing res-toration.
Courtesy Delphi Preservation Society, Delphi,
Indiana.
Fig. 8: Late 1920s photograph taken in Delphi, Indiana.
In the photograph are storefronts with prismatic glass
transoms. Gerard Collection, Courtesy Delphi Preserva-tion
Society, Delphi, Indiana.
UNCG The Historic Dimension Series: 6
tained. Figures 6 and 7 illustrate the aesthetic beauty of
prismatic glass that has been properly maintained. The
continued use and upkeeping of this building material
is important because it represents a significant time in
building design, construction materials, and daylighting.
As the quest for renewable energy in the twenty-first
century continues, it is possible that the use of prismatic
glass, or a material of the like, will see resurgence again.
There is much to be learned from previous generations;
all we have to do is look at what they have left us.
Bibliography
Ayres, M., Williams, J., & Wood, T. (1918). Healthful
Schools: How to build, equip and maintain them. Cambridge
Massachusetts: The Riverside Press Cambridge.
Blatner, H. (1948). Trend in Materials and Design. Review
of Educational Research, 18(1), 44-51.
Boyd, R. (1951). The Development of Prismatic Glass
Block and the Daylighting Laboratory. Egineering Re-search
Bulletin, 32, 1-88.
Gelbloom, M. (1978, March). Old Storefronts: 1870-1920.
The Old-House Journal, 6(3), 25, 33-34.
Jandl, H. W. (1982). Rehabilitating Historic Storefronts.
National Park Service, Preservation Tech Notes, (11).
Jester, T. (1995). Twentieth-century building materials: his-tory
and conservation. New York: McGraw-Hill.
Marinelli, J. (1988, August). Architectural Glass and the
Evolution of the Storefront. The Old-House Journal, 16(4),
34-43.
Neumann, D. (1995). The Century’s Triumph in Light-ing:
The Luxfer Prism Companies and Their Contribu-tion
to Early Modern Architecture. Journal of the Society of
Architectural Historians, 54(1), 24-53.
Prismatishes Glass = Prismatic Glass. (1995). Detail,
35(1), 22-23,24.
Randl, C. (2001). Repair and Reproduction of Prismatic
Glass Transoms. National Park Service, Preservation Tech
Notes, (44).
Willmert, T. (1999). The Power of Light [Prismatic Glaz-ing].
Architecture Minnesota, 25(1), 15, 58.
Images
Figure 2: National Park Service, Chad Randl
Figure 3, 4, 5: U.S. Patent Office
Figure 6, 7: Author
Figure 1, 8, 9, 10: Delphi Preservation Society, Delphi,
Indiana
Figure 11: HABS
The Historic Dimension Series is a collection of briefs
prepared by UNCG students under the direction of
Professor Jo Ramsay Leimenstoll. For information on
other topics in the series please visit the website at
go.uncg.edu/hds
Fig. 11: Example of prismatic glass block.
Fig. 10: Restoration of the Opera House’s prismatic
glass transoms. Courtesy Delphi Preservation Society,
Delphi, Indiana.
