Tackling Art Samples

This summer I’m looking at Peale paintings but I’d only ever worked with references before this summer, never art samples. In order to become comfortable with them, I’ve looked at Dr. Wustholz’s old art samples from their first paper and found some interesting things:

  • Art samples are tricky little buggers! No matter how small my reference sample is, it will never be as small as the art samples I get from Shelley. Their small size makes it very easy to move the laser straight off of the sample and into the colloid or onto glass without seeing evidence of the dye.
  • Another challenge is finding the perfect balance of power and acquisition time to get a good signal to noise ratio without photo bleaching the sample. Which brings us to another interesting thing I learned!
  • Photo bleaching! Photo bleaching occurs when the dye is provided with so much energy that new bonds are breaking and others are forming, also called photo chemistry. We don’t want photo bleaching to occur because these new bonds are permanent and form new SERS peaks in a spectrum. The new peaks make analysis difficult, if not impossible, because they can replace the bonds we need to identify an art sample as carmine instead of madder lake and vice versa.

So I’ve spent the last couple of week learning how to get the best spectra possible with different powers, acquisition times, and different spots on the sample itself. While photo bleaching will always worry me, I know I have to go to higher powers if I ever want to get good spectra from art samples. Working with old art samples and samples from other artist’s paintings has boosted my confidence in order to tackle the Peale paintings.