19th Century Window, Waterbury, Connecticut

Restoration

There are many variables that contribute to the life expectancy of a stained glass window. The type of lead and the manner in which it was milled, the quality of the glass, the skill of the original glazier and the quality of previous restorations, as well as, the structural integrity of the design, climate and atmospheric conditions within a building, pollution, vandalism, and the willingness of the owner to fund needed repairs are only a few of the components that determine the scope of work necessary for restoring a window. In any case, all stained glass windows fail at some point and require renovation. Typically, the lead in a traditional window will last for about seventy-five to one hundred years. Traditional stained glass studios often bought leads that were milled locally, and the quality of the lead could vary enormously from place to place. Leads that contained trace elements of tin and silver, for instance, might last much longer than those fabricated from pure lead. Over time the expansion and contraction of a window, as well as its weight, causes the microscopic structure of the lead to break apart. This, combined with the loss of brittle and cracking waterproofing material allows the window to warp back and forth until the lead matrix breaks, causing glass to fall out, break or shatter. If the windows were poorly made, or the reinforcement was not planned well, the inevitable problems are usually accelerated and aggravated.

The typical process for restoring a stained glass window involves a number of standard procedures. The window is first removed from its wood or stone sash, and a rubbing is made of the lead matrix, outlining the exact position of each piece. The lead is then cut away from the glass, using a wet process to prevent exposure to oxidized lead dust. At this point the glass is cleaned, and broken pieces are either fused back together or replaced. Fragile painting must be painstakingly preserved and consolidated. The irony of the restoration process is that the windows may have been restored many times before and, depending upon the skill of the restorer and their commitment to restoration, it is sometimes difficult to "see" the intention of the original artist. After all of the glass has been cleaned and broken pieces rejoined or replaced, the window is now reglazed using lead profiles as close as possible to the originals. For museum quality conservation, other steps including careful documentation of any old or new cracks, exactly matching lead profiles, as well as the use of clear, slumped pieces plated to fragile or broken glass may be necessary. Once the old glass is leaded together in its new framework it is now waterproofed, and the result is a sparkling window that, under normal circumstances, should remain strong and vibrant for a hundred years.

Restoration of LaFarge Window

Quincy, Massachusetts