Party Time or New Photo Light?

By Tessa de Alarcon

The conservation department recently acquired a new light for multi-modal imaging – an ADJ MEGA PAR Profile Plus (one for use at the conservation lab annex and one for the museum main lab). The MEGA PAR is a tunable LED light source, with 64 different color channels. While not designed for analytical imaging, it provides a bright and large spot size that we can use for visible induced infrared luminescence (VIL) imaging of Egyptian blue. It will also be something we can use to test out other imaging methods in the future. Taking VIL images is not new to the lab, but the light source we had been using stopped working and we needed to replace it. We are grateful to Bryan Harris for making the purchase of the new equipment possible.

The spectralon and the new MEGA PAR Profile Plus light (right) and the new equipment in use (left)

Along with the new light, we also acquired a new reference standard, a 99% reflectance spectralon. This standard is critical for developing methods and standard procedures for imaging in the lab. In this post I am going to show an example of how this standard can be used and how I developed a protocol for VIL imaging with the MEGA PAR light.

Set up for round one testing: Egyptian green (left pigment sample) Egyptian blue (right pigment sample) and a V4 QP grey scale card.

Since the MEGA PAR light is new, one of the first things I did when it arrived (after unpacking it and reading the instructions of course) was run a variety of tests on known reference materials to see what settings might work for creating visible induced infrared luminescence images of Egyptian blue. As part of that process, I set up a grey scale card (QP card V4) and two reference pigment samples, Egyptian blue and Egyptian green (both from Kremer pigments). I chose these so I would have a known pigment that should luminesce, the Egyptian blue, and one that should not, the Egyptian green. Using the department modified full spectrum camera, I took a visible reference image of the known pigments and the QP card using our regular fluorescent photo lights and a visible bandpass filter over the camera lens so that I could have a normal color image.

Screen shot of thumbnail images of the round 1 testing

Then I captured a series of images using the same set up but replacing the visible band pass filter with an 830nm long pass infrared filter so that I could capture images in the infra-red, with the fluorescent light turned off and the MEG PAR turned on. Each of the images I captured were with the same settings on the camera and with the MEGA PAR light in the same position, just going through each of the 64 color channel options.

Screen shot of Adobe Camera RAW showing the process for evaluating the response of Egyptian blue to each setting

I converted the images to grey scale adobe camera RAW by sliding the saturation level from 0 to -100, so that the red, green, and blue values (RGB) would each be the same. I then used the dropper tool to take a reading over where the Egyptian blue standard is in each image and recorded the number. The higher the number, the brighter the luminescence.

Set up for round 2 testing with the Egyptian blue pigment sample (top left), the Egyptian green pigment sample (below the Egyptian blue), the 99% reflectance spectralon standard (right), and a V4 QP grey scale card (bottom).

After doing that I had a reduced set of options that produced good luminescence in the Egyptian blue for a second round of testing. For round two I did the same thing with the more promising group, but also included in my images the 99% reflectance spectralon standard so that I could check and verify that the light is not producing infra-red radiation. If there is any infra-red, than the 99% reflectance standard should be visible. None of the second round of options showed any infra-red. While any of them can be used for VIL, CL08 gave the strongest response.

Screen shot of round 2 testing evaluation

After developing a working set-up, I did a test in the photo studio using an object that I knew had Egyptian blue, and the standards. I captured a visible image with the modified camera with the visible band pass filter and the fluorescent photo lights, and a VIL image with the 830nm long pass filter and the CL08 setting on the MEGA PAR. The false color image was created by splitting the color channels on the visible image in photoshop, discarding the blue data, and putting the VIL data in the red channel, the red visible data in the green channel, and the green visible data in the blue channel. As you can see the spectralon is not visible in the VIL image meaning there is no IR radiation being produced by the MEGA PAR light.

Images of E12974 with a visible image (left), a visible induced infrared luminescence image in the center showing Egyptian blue in white (center), and a false color image showing Egyptian blue in red (right).

After all this work, I had an opportunity to see how the new light would perform in less than ideal settings. I have been working on a study of one of the coffins in the collection, 2017-20-1.3, to examine the coatings and pigments. VIL is the perfect method of identifying blue areas on the coffin but the coffin is too big to fit in the department photo studio. The set of images below were taken in the Artifact Lab (our public lab in a gallery space) where there is IR from the windows (daylight) as well as from the gallery lights. I hoped that a short exposure with the new very bright MEGA PAR would reduce the effects of IR in the image. As you can see in these photos below, the 99% reflectance spectralon is slightly visible but not as clearly as the Egyptian blue on the coffin. These results are much better than what we used to get in the Artifact Lab using our old light, so I am very happy with these results.

Detail from the coffin 2017-20-1.3 with a visible reference image (left) a VIL image with Egyptian blue in bright white (center) and a false color image created by combining channels from the visible reference image with data from the VIL image resulting in the Egyptian blue showing up as red (right).

Special Photography for Larger Objects: Photogrammetry

By Christy Ching

Conservation Technician Christy Ching photographing the underside of an Egyptian coffin 2017-20-1.3 for photogrammetry.

One project I have really enjoyed working on as a pre-program conservation technician is documenting larger objects for a process called photogrammetry. Photogrammetry is a technology that gathers spatial and color information of an object from multiple photographs to form a geometrically corrected, highly detailed, stitched image called an orthomosaic. Essentially, photogrammetry creates a distortion-free, three-dimensional model of an object based on two-dimensional photos of every surface photographed in sections. 

Left: Four photographs of an ancient Egyptian coffin lid L-55-16B at various angles, which were used to create a 3-D model. Right: 3-D model draft of L-55-16B.

*L-55-16B (21-46-9) is a loan object from the Philadelphia Museum of Art (PMA)

This can be done for objects of any size. However, we are mostly reserving this technique for larger objects, specifically larger textiles and Egyptian coffins. This is because photographing the coffins and textiles normally with a single shot requires a greater distance between the object and the camera in order to fit the entirety of the object into the frame, and doing so reduces the image quality. Not only that, but the camera distortion that is inherent in all photographs will become more obvious. The resulting image will not be an accurate representation of the coffin or textile, which is not ideal for documentation purposes. 

The image on the left is a single-shot photograph of L-55-16B while the image on the right depicts the same coffin lid created by photogrammetry. When comparing the two images, the camera distortion in the single-shot photograph can be seen especially in the feet and head of the coffin lid.

With photogrammetry, we can take parts of the 3-D model and use them as high resolution, distortion-free, 2-D images of the object instead.

Six views of L-55-16B depicting the top, interior, and the four sides of the coffin lid generated using photogrammetry.

So far, a little less than ten coffins, a few textiles, a pithos fragment, and a giant granite relief have been documented using photogrammetry. The models and orthomosaic images are all generated by Jason Herrmann from CAAM, and we are very grateful that he is doing this for us! To learn a little bit more about the photogrammetry process, view this Digital Daily Dig here.

This project was made possible in part by the Institute of Museum and Library Services.

An Ivory Figure from Hierakonpolis: Part II

By Tessa de Alarcon

E4893 before treatment

The figure you see here E4893 is an ivory statuette from the site of Hierakonpolis. In a previous blog post I discussed the X-radiography that helped me determine that the large fill around the waist of the object could be safely removed. Based on that X-ray, I was able to mechanically remove the soft fill material and separate it from the object.

E4893 during treatment: both images show the object during fill removal.

Sometimes the full picture is not always clear from an X-ray. While I was able to remove the fill material and the nails, one thing that was not apparent on the X-ray and only became clear during treatment, is that part of the lower half of the object was embedded in the fill. This section also keys into the upper fragment. This may seem like a minor detail, but it is very important for knowing how the pieces should go back together. The loss in the waist is large and a fill is needed to stabilize the object structurally. One worry I had as I approached this treatment, was figuring out what the fill should look like and how elongated should the body be. However, once I found that in the fill there was a section of the object that keyed the bottom and the top pieces together, I knew that the placement of the two fragments could be conclusively determined.

E4893 During treatment: after the break edges were cleaned. The red arrows point to the part of the object which determines the size of the fill as it fits into the break edge of the top half of the object.

Even knowing how the pieces should go together joining the pieces was far from straight forward. The point of contact is too small for an adhesive join without fill material taking the weight of the fragments or to relay on the connection to hold the pieces in alignment during loss compensation. I had to instead figuring out how to support the fragments in the correct alignment while I created the fill. I decided that the best way forward was to create a removable fill using an epoxy putty. This is a fill that has to be adhered in place, as if it were another fragment, rather than relaying on the fill material to adhere or lock the fragments together. This means that I needed a barrier layer between the fill material and the object, and a system to hold the pieces together. The barrier layer is meant to prevent the fill material from sticking or adhering to the object and you will see in the images below that there is cling film between the epoxy and the object that I used as a barrier layer. The support system, however, took some trail and error before I found a method that worked.

E4893 during treatment on the left is the first attempt at filling the loss with the object resting flat. The image on the right shows the object during the second attempt using a foam support system inspired by the rigging at CLA.

First I tried laying it flat in a bed of glass beads to support the object, but this did not work, it was too hard to see if I had everything lined up correctly and the fragments kept shifting as I put the epoxy in place. Taking inspiration from my colleagues working on Egyptian monumental architecture at the conservation lab annex (CLA). I decided to try making a rigging system in miniature to hold the fragments in place vertically. This allowed me to see the object all the way around and check the alignment more reliably. However, my second attempt using a vertical support system with the object upside down, still led to too much shifting when I tried to put in the fill material.

E4893 during treatment images showing the final system used to support the fragments during placement of the fill material. The image on the left shows the back during fitting and on the right is a view of the front after placement of the fill material.

As a result, I adjusted the system from the second attempt and put the object right side up, carved a chin rest for the figure into the foam support and added a piece of foam to the back to hold the upper fragment more securely in place. The wooden skewers you can see in the images are used to hold the foam pieces together. My third attempt was very effective at holding the object in place in a rigid way with no shifting and gave me plenty of visibility to check the alignment.

E4893 during treatment. The image on the left shows the object with the fill dry fit into place (no adhesive had been applied yet). The middle and left images show the object after the fill was adhered in place and the gaps filled.

After I made the fill, I sanded it smooth and checked to make sure it fit right. Here you can see if dry fit in place and after everything was joined together. This should be a much more reversible treatment than what was done before should this treatment need to be redone again at some point in the future. While the object does not look all that different from the way it did before treatment, it is much more stable now with materials have better aging properties and allow for easier retreatment should that be needed.

E4893 After treatment

This project was made possible in part by the Institute of Museum and Library Services

An Ivory Figure from Hierakonpolis

By Tessa de Alarcon

The figure you see here, E4893, is an ivory statuette from the site of Hierakonpolis that I am working on as part of an IMLS grant funded project. I have just started the treatment, but thought I would give a brief run through of the initial examination since this is a good example of when and why we use X-radiography in our department to evaluate the condition of objects before treatment.

Before Treatment photograph of E4893

You may have noticed that the middle of this object is fill, so not part of the object. The fill has some cracks and splits that suggests it is unstable and should be removed. There is no written documentation for when this fill was done or by who, but it’s possible that this was done shortly after it was excavated. The object was accessioned in 1898. Given that the conservation lab at the Penn Museum was not founded until 1966 that leaves a big gap for the possibilities for when this treatment might have been done.

Annotated before treatment photograph of E4893 indicating the large fill at the waist of the figure.

Based on previous experience, I often worry with these old fills that there are unseen things, like metal pins or dowels, lurking below the surface. X-radiography is a great way to check for these types of hidden previous treatment issues. Though in this case, what I found when I X-rayed the object was not your typical pin or dowel.

Before treatment photograph of E4893 (left) and an X-ray radiograph of the object (right). The X-ray was captured at 60kV, and 6mA for 6 seconds. There are four nails visible in the fill.

Here in the X-ray you can see what I found: while this fill did not have any pins or dowels, whoever had done this treatment had decided to reinforce it by putting nails (4 in total) into the fill material. While this makes the figure look like he has eaten a bunch of nails, it is in some ways better news than a pin would be. Pins usually go into the original material, and if they are iron, can rust and expand causing damage to the object. Pin removal can also be risky and lead to damage of the object especially if the pin is deeply imbedded or corroded into place. These nails, on the other hand, appear to be only in the fill and do not look like they go into the original material of the object at all. This suggests that removal of the fill and the nails should be possible without damaging the object. As this treatment progresses, I will follow up with additional posts and updates.

This project was made possible in part by the Institute of Museum and Library Services

A Puzzle without all the Pieces: Treating Papyri

By Jessica Byler

The condition survey of our papyri collection is complete – I counted almost 4,300 fragments of papyrus and vellum, more than we realized were there! The papyrus ranged in size from a few millimeters to 9 feet long. Now, I have moved on to treating a few of the papyri that will be on display in the new Egyptian galleries.

Many of the papyri are sandwiched between pieces of Mylar. Static from Mylar can lift off friable ink or even split the two layers of the papyrus fibers and damage the papyrus. In order to safely remove the papyrus, I use a MinION 2 Ionizing Blower to eliminate the static charge. After removing the papyrus from the Mylar, I can then remove old repairs, realign fragments and fibers that are out of place, and apply new tissue paper bridges. Using a light box can help me identify joins and keep fragments in alignment. Papyrus fibers have different thicknesses, widths, and orientations, so transmitted light from a light box reveals the unique fiber pattern.

Left: Removing papyrus (49-11-1) from a Mylar enclosure using an ionizing blower
Right: Using a light box to realign fragments

Let’s look at one papyrus I am currently treating: a Temple robbery papyrus (49-11-1), dated to the 20th Dynasty or 11th century BCE. Along with removing old materials that might harm or obscure the papyrus, a key reason I am treating this particular document is to make sure the joins are right. It is fragmentary and there have been several treatment campaigns to repair it using a variety of materials, including Scotch tape, Japanese tissue, and Document Repair Tape.

Temple robbery papyrus (49-11-1), before treatment

I removed the old repairs where possible and reassessed the location of the fragments. At some point, several of the fragments have become misaligned or detached. In several instances, the fragments were just slightly out of line and could easily be nudged back into place. However, I quickly noticed some issues with a long fragment on the far left (on the right in the photo of the back below), and a small rectangular fragment at the bottom.

Left: detail of the back of the right section before treatment
Right: Section under transmitted light from a light box, with red arrows pointing to the two fragments in the wrong spot

On the long fragment, there are ink marks either side of the join which do not meet up. If the fragment was in the correct location, you would expect the writing to extend over the break. On the smaller fragment, the color, curvature, and thickness were different than the surrounding fragments. Using transmitted light, it is clear the fibers of these fragments do not actually line up correctly. Although at first glance they might not look out of place, they clearly do not belong there.

Left: Detail of front, with red arrows pointing to ink which does not meet up
Right: Detail under transmitted light, with red arrows showing that the fibers do not line up

The long fragment has two lines of writing at the top, so the number of locations it could join was limited. The small fragment at the bottom did not have any writing on it, so it was harder to determine its orientation and position. To add to this complicated puzzle, these pieces also might not join to any of the extant fragments.

Left: Detail of back during treatment, with the two fragments, indicated with red arrows, properly aligned
Right: Detail of back during treatment, with red arrows pointing the two fragments, and blue arrows pointing to some of the new bridges; areas of white residue from the old materials is also visible

Thankfully, their proper locations were easy to find using a light box. As you can see in the detail photos above, the fibers of the papyrus were a perfect match. The tissue paper bridges I used were around the size of a grain of rice and are clearly visible but blend in nicely with the papyrus. The Temple robbery papyrus is now ready for display!

Temple robbery papyrus (49-11-1), after treatment

This project is funded by the Antiquities Endowment Fund (AEF).  The AEF is supported by an endowment established with funds from the United Stated Agency for International Development (USAID).

Papyri Project

By Jessica Byler

This fall, I started a survey of our Egyptian papyrus collection thanks to an ARCE (American Research Center in Egypt) grant. The goals of the survey include preparing and rehousing the collection to be moved to a new storeroom, identifying unstable papyri that need to be treated, and getting some of the papyri ready for exhibit. The Penn Museum is in the process of redesigning the Ancient Egyptian and Nubian Galleries, and the curators have identified around 70 papyri they would like to include. Part of my job is treating and rehousing these papyri and making recommendations on their display.

E16423, a private letter in Arabic

What is Papyrus?

The papyri in our collection are mostly manuscripts. A sheet of papyrus is made of two cross-laminated layers of thin fiber strips made from the stems of the papyrus plant (cyperus papyrus). One layer of fibers is laid vertically, and the other is laid on top horizontally, creating a sheet with a grid pattern. Individual sheets were then overlapped and joined to create rolls. These rolls could be used as a single, long sheet or could be cut down as needed. The side with the horizontal fibers is called the recto (think “right side”), and the side with the vertical fibers is called the verso (think “reverse”). Scribes often wrote on the recto along the horizontal fibers, though some scribes wrote against the fibers or on both sides of the sheet.

A piece of modern papyrus through transmitted light
E2751, some vertical fibers are missing, revealing the horizontal fibers from the other side

Looking for a join helps identify the recto. Most joins are horizontal fibers to horizontal fibers, though some are horizontal to vertical. Look along the horizontal fibers and see if they continue across the sheet. If they do not line up or if there is a clear overlap, that’s likely a join.

E16323, horizontal to horizontal join. The red lines indicate the direction of the fibers and join.
E16411B, vertical to horizontal join. The red lines indicate the direction of the fibers and join.

Scribes used brushes or reed pens to write on the papyrus sheets. Inks were made from mixing ground up pigments into a binder. The most common ink was carbon black or soot bound with gum to make black ink. Scribes also sometimes used red ink made from red ochre, iron gall, and sepia, among other pigments. Some papyri are thickly painted with gypsum, metal oxides, and earth pigments.

E3068, a painted papyrus manuscript
83-1-1I, a manuscript with both carbon black and red ink

Penn Papyrus Survey

The Penn Museum has around 1200-1800 papyri featuring a wide range of personal, legal, administrative, literary, and religious texts in six languages: Arabic, Greek, Coptic, Hebrew, Demotic, and Hieratic. The collection spans around 4000 years, from the Old Kingdom to Islamic Egypt. These include Books of the Dead, Homer’s Iliad, and the Gospel of St. Matthew. There are also groups of small fragments which have not been reconstructed or studied. The Penn Museum’s collection of papyri has never been the subject of a concerted conservation campaign – until now.

Most of the collection is currently encapsulated in Mylar and stored flat in manila folders or sandwiched between two glass plates. I am surveying the collection at the object-level, one by one. I examine, measure, and record each piece, noting the structure of the papyrus, how it is housed, old mends or treatments, condition issues, and if it needs to be rehoused or conserved. I follow the examination and documentation with photography. Images are available on our Digital Collections webpage.  Hopefully with the new photos and documentation, this collection will be more accessible to papyrologists and scholars around the world.

Photographing papyrus using a copy stand

More Information

Eventually, the information on the Penn Museum papyri collection documented in this survey will be included in the Advanced Papyrological Information System (APIS) database, where only a small fraction of our collection is represented today. There are a number of great resources if you would like to know more about the structure and conservation of papyrus. The University of Michigan, which holds the largest collection of papyri in North America, is active in papyrological research and education. The Brooklyn Museum and NYU have both recently done similar projects and have great blogs about their collections as well.

This project is funded by the  Antiquities Endowment Fund (AEF).  The AEF is supported by an  endowment  established  with  funds  from  the  United  Stated  Agency  for  International Development (USAID).

Horus gets a facelift

By Anna O’Neill, Alice and Herbert Sachs Egyptian Collections Conservator

When I last wrote about transforming a stela, I wrote about removing an old coating on a small stela fragment. Well, stelae come in all shapes and sizes, and I just finished treating another one!

We just opened Ancient Egypt: From Discovery to Display, which highlights some of the Penn Museum’s Egyptian artifacts while our larger galleries are being renovated. This was the perfect time for some of the pieces that have always been on display to come into the conservation lab for a little bit of TLC (tender loving conservation).

This stela is a black quartzite monument for the pharaoh Qa’a, the last king of the First Dynasty in Egypt, around 2910 BCE. It is about five feet tall and shows a falcon representing the god Horus standing atop a serekh (a boxy decoration representing a palace) containing the hieroglyphs for Qa’a’s name.

The Penn Museum Qa’a stela (E6878) before treatment with old restored areas outlined in red (left) and the Cairo example (right). A letter from Penn Egyptologist Sara Yorke Stevenson to the archaeologist William Flinders Petrie in 1901 declares that the restoration “gives an idea of life”.

As you can see in the image above, the stela was heavily restored with cement in the early 1900s to make it look whole. Unfortunately, the restoration had given Horus a somewhat comical expression. With a big beak and tiny eye, he looked perpetually disappointed and definitely not stylistically appropriate for his time. Fortunately, our statue has a mirror twin in the Cairo Museum, which it would have been paired with on site in Abydos. Because the one in Cairo is mostly intact, we can use it as an example of what ours would have looked like. The head and beak are much smaller and simpler, giving Horus the look of a bird of prey. With the curators, we decided to give Horus a facelift based on the Cairo Museum example.

First, we did some digital mock-ups of how the head would look before I painted the outline directly onto the restored area. Using a Dremel rotary tool with a grinding stone attachment, I shaped Horus’s head and beak to more appropriate proportions, which was a very dusty but very satisfying process. Since we didn’t have any good examples of what the eye might have looked like (the Cairo Museum face is damaged), I filled this area using Paraloid B-72 and glass microballoons. I also sanded down the squared-off edges of the restored border so they sloped down into the background, again like the Cairo Museum stela, and smoothed some of the rougher areas of restoration.

Horus’s reconstructed head before treatment (left), with rough digital sketch (center), and during reshaping with the Dremel (right). Please note that I only reshaped what I knew was the restoration material! Conservators never make changes to original parts of objects.

Once the curators were happy with the shape of Horus’s head, it was time to move on to painting. The previous paint that covered the cement was a color that didn’t quite match any of the tones in the stone – fine for display in a dim gallery, but the stela’s new home would be more brightly lit. Finding the right color was challenging because the top fragment, which was found a few years after the bottom pieces, is a slightly darker color than the rest of the stela. I decided on a mid-tone that worked with the base color of the surrounding original stone, and then used a sponge to layer lots of highlights and darker shades to blend in with the actual artifact. I also used paint to create the optical illusion of “finishing” the bottom left corner of the serekh so that it appears complete from a distance.

The Qa’a stela after reshaping and repainting the old restoration.

You can now see the Qa’a stela and lots of other amazing Egyptian artifacts in Ancient Egypt: From Discovery to Display. The Artifact Lab has also reopened, and we look forward to being able to talk to everyone about the work we’re doing to prepare for all the exciting changes at the Penn Museum.