Using near-IR spectroscopy, Fourier transform infrared spectroscopy, and micro-X-ray fluorescence to learn about this document's condition
The Life and Morals of Jesus of Nazareth, more commonly known as the Jefferson bible, is a volume created by Thomas Jefferson containing passages he chose from the four Gospels of the New Testament. Jefferson cut these passages out in four different languages and pasted them on to blank pieces of paper which were then bound into a book for his personal use. A team of four conservators has been tasked with documenting the current condition of the volume, formulating a conservation plan that addresses identified issues, and carrying out an ethical and appropriate conservation treatment to ensure the book can be viewed and enjoyed by future generations.
Knowing what materials Jefferson used when he made The Life and Morals of Jesus of Nazareth helped conservators predict how the artifact would change over time. Observations made during a visual examination and survey of Jefferson's volume were empirically confirmed by more detailed material analyses, and the results from these tests helped conservators determine what conservation treatment would be most beneficial for the volume.
Conservators took microscopic samples of the twelve different types of paper, ten different kinds of ink, and two different adhesives present on the volume's pages. Sampling locations were carefully chosen to not interfere with printed or written text or to alter the aesthetics of a page. For example, samples from Jefferson's handwriting ink were never taken from intentional writing locations, but rather were taken from stray splashes of ink along a page margin. The sample sizes, measured in units of one thousandth of a millimeter, ranged from 20 to 200 microns -- they were so small, that they were nearly invisible without the aid of a microscope.
Collaborating with colleagues at the Smithsonian's Museum Conservation Institute, conservators employed various types of non-destructive materials analysis to study the composition of the samples taken from the book in order to understand what they were made of and if they are prone to degradation. Micro-X-ray fluorescence (XRF) was used to identify traces of inorganic elements, such as calcium, magnesium, zinc, aluminum, potassium, sulfur, copper, and iron. Knowing whether these elements are present in the papers and inks helps us determine the rate of deterioration. Fourier transform infrared spectroscopy (FTIR) was used to detect the presence of organic elements in the inks and adhesives; this analysis revealed that the adhesive Jefferson used to adhere the clippings to the pages contained both animal glue and starch, which is water soluble.
Conservators carried out additional analyses that did not require taking samples from the pages. Near-IR spectroscopy (NIR) was used to measure the amount of gelatin present on the surface of the paper. Papermakers applied gelatin to their new sheets of paper to prepare them for printing and to keep the ink from running or smudging; gelatin protects the paper fibers and reduces the rate at which they deteriorate. Polarized light microscopy helps us identify what plants were used to make the paper by studying the shape of the individual fibers. Micro-chemical testing determined whether the iron content of the handwriting ink would cause more discoloration and breakdown of the paper. A variety of solvent and water mixtures were tested to determine if the pages could be safely washed to remove the acidic by-products of degradation.
Because certain elements reflect light in uniquely identifiable patterns at different light wavelengths, conservators were able to use specialized imaging to examine the artifact's state of degradation. Ultra-violet light revealed previously unseen stain patterns on some pages of the artifact. Infrared spectroscopy allowed conservators to "see through" Jefferson's manuscript inks and examine the paper beneath the writing, checking to see if the acidic inks had damaged the paper's structure. A colorimeter, an instrument which uses reflected light to record the exact color value of the object beneath it, was used to take multiple readings on every page of the Jefferson Bible at specific locations. Because paper yellows as it ages, the darkening of an artifact, as evidenced by changes in its color values, can help predict the rate and degree of the paper's degradation.
These varied chemical analyses provided quantifiable data that helped conservators to determine the artifact's chemical condition and to propose and authorize viable conservation treatment options. In our next blog post about the Jefferson Bible Conservation Project, we will describe the chosen conservation treatment methodology, beginning with the delicate process of taking the volume apart to treat the individual pages. Stay tuned.
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This post was first published on the National Museum of American History's O Say Can You See? blog.
Images: 1. Microscopic samples of paper fibers and ink; 2. Unidentified staining not visible in normal light, but appears under ultraviolet light/Smithsonian Institution.