Dr. Fenella France touched on many questions near and dear to any conservation scientist’s heart, including my own, during her talk at the Research and Technical Studies session on Thursday morning. 1) How can effectively controlling environmental parameters reduce the need for invasive intervention? 2) What is the nature and impact of the interaction between media and substrate and 3) How can our findings, as scientists, impact the production of artists’ materials?
Her talk focused around the investigative research launched by the Library of Congress to study Herb Block’s political cartoons after a recent exhibit. You can see a synopsis, as well as digital images of many of Herblock’s cartoons at the Library of Congress’s exhibit page here. This research looked into the effects of environmental conditions on the cartoons, both in storage and while on display, while also attempting to understand the nature of the interaction between the media, in this case ink from porous point (felt-tip) pens, and the substrate.
The Preservation Research and Treatment Division of the Library of Congress has a whole host of instrumentation and equipment to conduct thorough measurements of minute changes in ink color and chemistry. Frequently, spectral imaging can be employed to non-invasively probe these minute changes in an efficient manner. Using a combination of thin layer chromatography (TLC) and spectral imaging, not only was Dr. France and her team able to determine effects of storage and light exposure on a wide variety of different pens, but they were also able to discover which dye components of the inks were the most susceptible to alteration.
One possible outcome is that the TLC method their lab developed to study the fading of individual dyes might also lead to an effective way of studying the degradation products that are formed through the fading process. Spectral imaging is a wonderful method for quickly determining changes in a material over time by examining changes in the characteristic absorption/reflection spectra of those materials. However, there is not any specific structural information present in this data. In order to answer the question of what degradation materials might be forming and if those products might be harmful for the substrate, an extraction procedure could be done on the TLC plate of the individual spots. Then a method like mass spectrometry could be used to answer more chemically specific questions. This is just me projecting ideas onto their project at this point, but what a cool information source this could be!
Ultimately, and in regards to the third question I mentioned above, the results of the Library’s (and Dr. France’s) study made it back to the pen manufacturers. Taking the information about the different rates of fading observed in the individual dyes, one of the companies actually changed their pen formula in order to make it more fade resistant. A sample was given to the Library of Congress to test, and, sure enough, passed a whole slew of fading tests! It’s always nice to see the results of a conservation experiment impacting the real world for present (and future) cartoonists.