Dating and Documenting Historic Leaded Glass

     Before deciding on any treatment for historic leaded glass, every effort 
should be made to understand-and to record-its history and composition. 
Documentation is strongly encouraged for significant windows and other 
elements. Assigning an accurate date, maker, and style to a stained glass 
window often requires extensive research and professional help. A 
documentation and recording project, however, is worth the effort and 
expense, as insurance against accidents, vandalism, fire and other disasters. 
The better the information available, the better the restoration can be. The 
following sources offer some guidelines for dating leaded windows.

     Building Context. The history of the building can provide ready clues to 
the history of its leaded windows, doors, and other elements. The construction 
date, and dates of major additions and alterations, should be ascertained. 
Later building campaigns may have been a time for reglazing. This is 
especially the case with churches and temples. They were often built with 
openings glazed with clear leaded glass. Stained glass was added later as 
finances allowed. Conversely, the windows may be earlier than the building. 
They may have been removed from one structure and installed in another (this 
is more likely with religious structures). Bills, inventories, and other 
written documents often give clues to the date and composition of leaded glass.
Religious congregations, fraternal lodges, and other organizations may have 
written histories that can aid a researcher.

     Inscriptions and Signatures. Many studios and artists affixed signature 
plates to their work-often at the lower right hand corner. Tiffany Studios, 
like others, did not always sign pieces and the absence of an inscription 
cannot be used to rule out a particular studio or artist. Windows may feature 
dated plaques commemorating a donor. However, these do not always indicate 
the date of the window, since windows were often installed before a donor was 
found. Nevertheless, these features help establish a reasonable date range. 
James Art Glass Studio assigns a traceable work number and is signed and dated 
by the artist.

     Composition and Other Stylistic Elements. These elements are more 
subjective, and call for a fairly broad knowledge of architecture and art 
history. Do the windows fit the general style of the building? The style of 
the window may point to a general stylistic period (e.g., Arts & Crafts, Art 
Nouveau, Prairie School). The imagery or iconography of the windows may also 
reveal their overall historical context and establish a general time period.

     Framing and Surround. Framing elements and the window surround can reveal 
information central to dating the window. Do moldings match other interior 
trim? Has the opening been altered? Is the window set in an iron frame 
(post-1850s), a steel frame (generally post-World War I), a cast stone frame 
(seen as early as the 1880s, but popular after 1900), or a terra cotta frame 
(generally after 1900)?

     Reinforcement and Leading Details. Does the window or other element have 
round bars or flat bars? Flat bars began to appear about 1890; round bars, 
used since the Middle Ages, remained in use until the 1920s, when flat bars 
supplanted them. Cames can also give dating clues. Zinc cames, for example, 
developed by a midwestern company in association with Frank Lloyd Wright, 
first appeared in 1893. In general, however, dating a window by the came alone 
is difficult. Over one hundred varieties of lead came were available in the 
early 20th century. Moreover, came was sometimes produced to look old. 
Henderson's Antique Leading from the 1920s was made "to resemble the old hand 
wrought lead" and also carried "easy-fix" clip-on Georgian-style ornaments.

     Glass. The glass itself can help in dating a window. Opalescent glass, 
for instance, was patented by John LaFarge in 1880. Tiffany patented two 
variations on LaFarge's technique in the same year. (Opalescent glass is 
translucent, with variegated colors resulting from internally refracted light. 
It features milky colored streaks.) Pre-1880 glass is usually smooth 
translucent colored glass (painted or not); glass with bold, deep colors is 
typical of the 1880s and 1890s, along with jewels, drapery glass and rippled 
glass. But such flamboyance faded out with the rest of Victoriana by about 
1905. However, stained glass styles of the late 19th century continued to 
appear in ecclesiastical buildings after they passed from general fashion. 
Leaded beveled plate glass was popular in residential architecture after 1890, 
and was used profusely until the 1920s.

     The level of documentation warranted depends upon the significance of the 
window, but it is very important to document repair and restoration projects 
before, during, and after project work. Photographs will normally suffice for 
most windows (see "Photographing Stained Glass Windows" ). For highly 
significant windows (generally, those which were not mass produced), rubbings 
as well as written documentation are recommended. The leading patterns in such 
windows are complex, particularly in plated windows (which have several 
layers). Rubbings are therefore encouraged for each layer; they are invaluable
if a disaster strikes and reconstruction is required. Annotated rubbings of the
leadwork should be done with a wax stone on acid-free vellum.

     To document windows properly, inscriptions should be recorded word for 
word, including misspellings, peculiarities in type style, and other details. 
Names and inscriptions in or on windows can indicate ethnic heritage, 
particularly in churches or civic structures where windows often reflect 
styles and themes from the congregation's or community's origins. Lastly, any 
conjectural information should be clearly noted as such.