The Ford Conservation Center recently completed treatment on a series of 1920s cyanotype blueprints for a historic home in Walnut, Iowa.
Front elevation for the Ada Boiler House.
Original blueprints are a rare find for owners of old homes, and the information they provide can be invaluable for home renovation projects. These blueprints were found in the attic of the home by the current property owner. Generally speaking, attics (and basements) without climate control are considered to be some of the worst places to store paper documents. This is because uncontrolled fluctuations in temperature and relative humidity can cause deterioration over time, including distortions and brittleness. Exposure to moisture can cause mildew, mold, and staining.
Luckily, the blueprints had only minimal damages, despite being stored in the attic for many years. The 17 blueprints were tightly rolled together so that the sheets no longer laid flat. As a result of being stored in this way, they were protected from light exposure and have retained their vibrant Prussian blue color.
This set of 17 blueprints is very detailed for a residential structure. Some sheets even provide details for decorative design aspects of the home, like gable cornices on the roofline, and brickwork over windows.
Additional damages reflected the fact that the blueprints were used as practical documents – three holes were punched along the left side of each sheet and corners were tattered from use. There are 2”-3” horizontal tears on the right edge of numerous sheets, in addition to smaller tears around the edges on many of the blueprints and a few small paper losses. A few pieces of tape were applied to the back of one sheet to repair a tear.
The first step of treatment was to reduce any surface dirt and dust that had accumulated on the sheets over time, and to remove the old pieces of tape. After cleaning, each sheet was humidified with aqueous moisture and flattened under weights to help reduce the curl. At this point, the tears were stabilized with paper repairs from the back. The repairs are made from lightweight Japanese paper and a reversible water-based adhesive.
The upper left corner of this first floor plan exhibits some blanching (fading of the blue pigments). This likely would have been much more widespread if the pages had been exposed to more light over time.
The client chose to limit the treatment to stabilizing the damages. For this reason, no aesthetic compensation was carried out. Aesthetic compensation for blueprints could include toning of media loss along the worn creases and tears to better match the blue ink.
What Is a Blueprint?
In the mid-1800s, “cyanotype” printing was invented, and the technique quickly became the standard for reproducing architectural drawings. First, a piece of white paper is coated with chemicals that turn the paper Prussian blue when exposed to UV light. Then the material to be copied is placed on top of the paper – this could be an original drawing, a photo negative, or even a plant sample—and placed under a UV lamp or in sunlight. Any part of the chemically-treated paper that is not “protected” by a layer of ink turns to a rich blue color.
An example of a cyanotype printed from a photo negative. Notice that the areas on the negative with the most ink stay white on the cyanotype, while the transparent areas have turned the darkest blue. Image source: Mathieu Stern
The Ada Boiler Home
The existence of these blueprints is not only a novel piece of history. The house, built in 1923, was designed by celebrated Omaha architects John and Alan McDonald, known for designing Joslyn Castle. It was commissioned by Ada Boiler, daughter of Ohio native and early Walnut settler Joseph Boiler.
The Ada Boiler house in Walnut, Iowa as it appears today. Image courtesy of Caeden Tinklenberg.
Over the past 100 years, the house has seen six different owners, the first two of whom were Boilers. Three of the succeeding owners were important members of Walnut’s vibrant antiques trade.
When the house was purchased by its current owners in 2022, it had suffered significant exterior damage from a recent hailstorm, interior water damage from a burst pipe, and a partially collapsed garage from a wind-felled tree. The owners are working to repair the damages and reconfigure elements of the house to be compatible with modern amenities (the original kitchen layout left no room for a modern refrigerator), while keeping the home as close to Ada Boiler’s original plans as possible.
