Restoring a Historic Stained Glass Window

One of my current projects is assisting with the restoration of a stained glass window at the San Francisco Swedenborgian Church, a National Historic Landmark. The window was designed by parishioner Bruce Porter and installed when the building was constructed in 1895. The restoration process requires removing the window to Nzilani Glass Conservation studios for a period of several months. To fill the gaping 40″ diameter circular hole,  we are creating a photographic replica.

Since the window is high on the east wall, to get close to the window and to shoot perpendicular to it would have required a scaffold. Instead I used a 300 mm telephoto lens to photograph the window from tripod level near the opposite end of the church. This minimized the angle and therefore the perspective distortion.

The first attempt was not encouraging. Although 21 megapixels enlarged to 40″ corresponds to almost 94 pixels per inch, the image quality just wasn’t satisfactory.

I went back and re-photographed the window, this time adding a 2X tele-extender and creating a 3×3 panorama which I stitched together using PTGUI. After cropping, the new image was 9750 x 9750 pixels – for a file size of almost half a gigabyte. Here is the resulting image, scaled for web display:

Bruce Porter's Dove Window as it looks in the church
Bruce Porter’s Dove Window as it looks in the church

In order to test different printing methods and vendors, we needed a smaller, but full-scale, section of the image. I created a file of a section that would print to 8×10″ at the 200 ppi resolution recommended by the printer. This image is shown below:

Dove window test piece. Prints to 8x10" at 200ppi.
Dove window test piece. Prints to 8×10″ at 200 ppi.

Several vendors and technologies were evaluated, including printing on transparency material and laminating on to plexiglas sheet. We finally settled on ink-jet printing directly on to plexiglas using UV-cured inks. Magnolia Editions of Oakland, California specializes in working with artists to print on exotic materials and was selected as the printer.

The next step is removing the existing window and replacing it with the replica without causing any damage to the building and with minimum disruption to the activities taking place in the church. That will be a challenge in itself!



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