NB: Before I try to blog about this talk, I need to say that…well, we didn’t really ever get to discussing Photoshop Assisted spectroscopy! Meaning, this blog will contain some interesting tidbits but you won’t be learning much about this technique or how you might use it in your lab/institution. Sorry!
The project highlighted in this talk was the analysis of the logbooks and writings of Dr. Nirenberg, a Nobel Laureate. Dr. Nirenberg cracked the genetic code (our DNA) and his writings are considered a national treasure. The bad news is that all of his writings were made using ballpoint ink and ballpoint inks are notoriously fugitive. This project used the Photoshop Assisted spectroscopy (is this just kind of like hyperspectral imaging???), and interviews with Dr. Nirenberg’s former technicians to figure out what different markings mean in the logbooks and writings (eg, there are occasionally red marks in the books which were used by Dr. Nirenberg to indicate points/data/results of interest). Also, drops/stains on the charts/files turned out to be because solvent was accidentally dropped onto the books during lab experiments.
http://en.wikipedia.org/wiki/Marshall_Warren_Nirenberg
INKS
* First ballpoint pen was patented in 1818; the pens were used to mark leather
* The inks contained within are not very archival and weren’t designed to be
* Ball ink is used by some artists and it will fade with time
* There are a lot of components in ink; dyes and pigments; solvents, resins, emulsifying agents, lubricants, viscosity modifiers; optical additives; anti-corrosives;
* The rolling ball at the tip of a ballpoint pen is supposed to plow through the ink, pushing it onto/into the paper. You can get buildup of ink at the front of the pen if the pen doesn’t work well and results in those goopy clumps you sometimes get;
*As soon as the ink comes out from the interior, the ink is oxidizing
*The roller ball can pick up residue from the surface of the paper and roll it back into the ink reservoir – this is not good because you can get a build up of garbage interacting with the ink.
*All new inks that are out there have fluorescing agents in them – to make ink look brighter with the artificial lighting used in most office spaces – this is a way you can differentiate modern inks from older ones when examining documents
* ballpoint ink pens is a $20 Billion/year business; the entire idea is for you to keep buying these products
* Before 1949 – inks in pens were oil based; these inks are very stable and you can use this information to help you differentiate when inks were applied to a substrate
* black ink is black because it has all the chromophores in it; when it degrades/separates, it changes color; other colors fade
* All inks have different fingerprints
When you get a historic document, you don’t know starting point of original ink. But you can look at the current state of the ink and you can start to understand degradation process.
SCANNING DOCUMENTS
A scanner is actually a spectrometer. Every pixel has an RGB value, but the computer mixes the colors for your eye. However, you can use those same values in a more creative way: If you consider the RGB values as values for a three dimensional space, you can use the values to plot them on a 3D map and track different types of inks used on historic documents.