Tag Archives: Infrared

Fun with PhotoDoc: Infrared Again (Edition 8)

It’s been a while since my last Fun with PhotoDoc post, so I wanted to share some progress I’ve been making with Reflected IR.  You might remember from my last PhotoDoc post, we purchased a modified UV-Vis-IR camera from MaxMax at the end of 2017.  Our first two objects we (Ashleigh and I) examined and documented with the camera were a great learning experience, but didn’t exactly leave me with goosebumps.  Still it was a good experience and we worked out the use of the various filters and the general IR workflow.
Fast forward to April when the lab received not one but two books from UC in need of IR photography.  The first was the Masters thesis of Ralph E Oesper from the Oesper History of Chemistry collection.  The curator wished to exhibit several of the pages from the volume, but upon inspection Ashleigh (our conservator) was concerned that the purple text ink might be dye based, which is very light sensitive.

The ink disappearing under near IR is a clear indicator that the ink is most likely dye based, and while that made Ashleigh very happy and validated her choice to create printed surrogates of the pages for exhibition, I still felt a little less than wow’d.  I was still waiting for a really compelling and dramatic IR example.
Enter volume 1 from the Third German Protestant Church of Cincinnati collection, an 18 volume collection of early Cincinnati baptismal, marriage, and funeral records from the Archives and Rare Books Library that pre-dates the city records.  In this case, Ashleigh wanted me to examine and document 4 pages within the volume with faint graphite inscriptions on paper with heavy foxing.

Side by side comparison of one page under normal illumination and near infrared

Finally!  A satisfying IR session with helpful results.  Documenting all four pages using reflected IR allows for the foxing to disappear from the page, thus making the faint graphite inscription easier to read.  After converting the IR image to grayscale I also upped the contrast significantly, allowing for better readability of the handwriting.  In the end, we now have four pages of legible inscriptions and I’m very happy with the results.

Click on an individual image to see the gif in action for that page…

I definitely still have a lot to learn when it comes to near infrared photography, but I would call this, not only a satisfying experience, but progress that will hopefully lead to a better workflow.  This round of IR photography definitely was not seamless, but I did learn more, as I do every time I shoot, and it is my hope that the more I do the more I will streamline and improve our IR workflow.

Jessica Ebert (UCL) – Conservation Technician, Lead Photographic Documentation Tech

Fun with PhotoDoc: Infrared (Edition 7)

At the end of last year the lab purchased a modified UV-Vis-IR Nikon through MaxMax so that we can start to play around with infrared photography.  Infrared photography (IR) is commonly used in fine art conservation as an examination tool.  Reflected IR can be helpful when trying to identify pigments, inks, coatings, etc. and transmitted IR can helpful for viewing watermarks, underdrawings, and linings. We’ve only just started dabbling with IR photography, but I wanted to share some photos from my most recent session with reflected IR.

This is a full leather photo album from the Public Library of Cincinnati & Hamilton County’s collection.  This early 1900s photo album contains hand-colored silver gelatin photographs taken by A. Nielen.   The photographs appear to depict his travels through the US and Canada, and various landmarks and neighborhoods of Cincinnati are represented.

This seemed like a good object for reflected IR because of the hand-coloring on the photographs and the white ink inscription below each photograph.  I began by taking a representative visible light image (first image below) using our modified UV-Vis-IR camera, incandescent lighting, and the X-Nite CC1 filter on our 50mm lens.  Then, being careful not to move the position of the camera or the object, I switched to the X-Nite 830 filter (830nm) and converted that image to grayscale in Photoshop (second image below).  Then I took my visible light image and my reflected IR image into Photoshop to create the false-color image (third image below).  The digital false-color image is a combined representation of the visible and infrared images, and it’s actually quite simple to make.  You basically copy and paste the various channels for the VIS and IR image as follows, green to blue, red to green, and IR to red.  The false-color image allows you to better differentiate and characterize the various materials (pigments, inks, etc.) and potentially even identify them if you have sufficient known samples to use as references.

Like I said, we’ve only just started using IR and we’ve got a long way to go, but I’m looking forward to experimenting and learning more about it as time goes on.

Jessica Ebert (UCL) – Conservation Technician & Photographic Documentation Tech