What’s all that 3D data for?

By Tessa de Alarcon

We’ve had a few posts (this one by Chelsea Kim and this one by Christy Ching) on creating 3D models using photogrammetry, and I thought I’d give some examples of what we are doing with that data once it’s collected. For some objects we are creating ortho-mosaics and these 2D images are going into reports as after treatment images as well as going into the catalogue model as record photography that also shows up in the online collection database. This wooden coffin 2017-20-1.3 is an example of this type of imaging.

2017-20-1.3 after treatment photos created using ortho mosaics generated from a 3D model created using photogrammetry.

For other objects we are also producing ortho-mosaics, but they are before treatment images. For example with E641 a wall painting that was previously on display.

E641 when it was on display

The wall painting is currently in two sections and each one has been imaged separately. These before treatment images have been used to create condition maps.

Before treatment ortho mosaics of E641 created with photogrammetry

The maps go into our reports and help provide visual documentation to support our written reports. For large objects, these kinds of condition maps are often easier to understand than written descriptions and can provide more precise information on the location of specific condition issues. Here you can see the condition map for E641. The map is not yet complete, I am still working on documenting one of the sections but I have combined the two maps into one image so you can see what that process looks like.

E641 condition map. The map for the section on the left is complete while the mapping on the section on the right is still in progress

The models can also be used to show surface distortion, so here in this screen shot of the 3D model of E641 you can see planar distortions in the wall painting where the fragments are not aligned. There may be a variety of causes leading to this distortion including poor alignment during the previous reconstruction or they may be the result of lifting/separation of the original material from its current modern backing.

Detail of E641. One the left is a mesh without the color added to the 3D mesh-model and on the right is the same area with the color and surface texture added to the model. The image on the left you can easily see the fragments and how they are misaligned in some areas.

I am currently working on learning how to create a 2D false color image where the colors reflect depth, so that we can have these planar distortions documented in 2D as well as being able to see them in the model.

So all together, this data is being used to document both the final condition of objects after treatment, as well as to document them before treatment. The models are also useful tools to assess complex condition issues and are valuable for evaluating next steps. For example, our current plan is to remove the wall painting from it’s current modern backing and put it on a new one. Our hope is to correct some of these planar distortions as a part of that process, and this model as well as one we make after treatment will be useful for evaluating the efficacy of the treatment and provide a base line for assessing its condition in the future.

2D to 3D

By Chelsea Kim

As an intern working with the conservation department, I have received the opportunity to work on many projects and experience things I never thought I would. Recently I have been working on this software called Reality Capture using photogrammetry. Photogrammetry is a process that uses an abundance of photographs to create a 3D model without any distortion from many overlapping images stitched together to form a detailed and geometrically corrected image called an orthomosaic. This process is usually used on larger objects, and this is because it’s too big to be in frame when taking pictures and has a lower quality with distortion which is far from perfect, and Christy Ching explains more in depth about this in her previous blog post.

I want to show how to create a digital three-dimensional model using the software, Reality Capture, and I’ll demonstrate with an example of the after-treatment photos of an Egyptian coffin.

To start off with, having pictures of the object is a must. For this example, they were already taken and edited in Photoshop, to adjust the white balance using adobe bridge ahead of time. Then I begin by opening the software and then under workflow at the top left corner, I select “inputs.”

Screenshot of the software highlighting where to click “Inputs” which is above “1. Add Imagery”

Then I select all the images making sure that they were a .jpeg file and then I click on “Align Images” as highlighted above. After the images are aligned, a transparent box surrounding the coffin appears. I adjust the box by dragging the control points around to make it as small as possible without cutting off any part of the coffin. As you can see in the image below, using E883C, the box is close to the coffin but does not intercept the coffin itself.

Screenshot of the Egyptian coffin E883C after the images were aligned with the transparent box adjusted to tightly around it.

Now for the fun part to see the coffin take shape, I click next to “Calculate Model” to select “Preview Quality” as highlighted below. Then I go to the tools bar to use the lasso option to erase all the unnecessary space around the coffin. Then after being satisfied with selected area, I click on “Filter Selection,” which turns the selected areas from orange to dark blue showing that it worked.

Screenshot of the coffin after selecting “Preview Quality.”

Finally, I go back to the Workflow bar to select “Texture” which is highlighted below and then it shows all the details of the 3D model without any distortion in high detail and quality.

Screenshot of the 3D model after being textured.

Cleaning Questions and Cross-Sections

Julia Commander is a third-year graduate student in the Winterthur/University of Delaware Program in Art Conservation. She is currently completing a curriculum internship at the Penn Museum.

The investigation of the painted Ptah-Sokar-Osiris figure continues. Previously, I mentioned that I would be taking cross-section samples to gain a better understanding of the paint layers. This type of sampling involves taking tiny (less than 1 mm) flakes of paint to capture the stratigraphy. Once I have a slice showing all of the layers, I can look at the edge under magnification to observe the structure from surface down to ground level.

In this case, I took four samples from representative areas on the figure in order to compare the layers. Before sampling, I looked at each area under magnification and made notes about surface characteristics and conditions. To sample, I continued working under magnification with a fresh scalpel blade.

L-55-29, cross-section sample areas. You can also see the darkened appearance of the front surface.

As you can probably imagine, handling a tiny little paint flake can be tricky. To make observation possible, conservators embed cross-section samples within a mounting material, typically a clear resin. Mini ice cube trays are perfect for making small blocks of resin for this purpose. After embedding the sample between two resin pours, one face of the cube is polished to a glossy finish. The polishing process helps to get a clean cut of the sample from an edge-on perspective.

Mounting cross-sections with a clear polyester resin, molded in a mini ice cube tray. The cubes are then polished with Micro-Mesh cushioned abrasive cloths.

You never know exactly what your cross-section will end up looking like until it’s under the microscope. Flakes can shift while the resin cures or be affected by polishing, so it’s an exciting moment to see the results. Sample X2, below, shows a clear view of the layer structure. Similar to the way conservators use ultraviolet (UV) light during object examinations, cross-sections are often viewed with various light sources to show different properties. Here, you can see the sample in visible light and UV light (365 nm).

Sample X2, 100X total magnification, in visible light (right) and ultraviolet light (left). Samples were viewed on a Zeiss Axio Scope.A1 polarized light microscope.

We can see a few interesting features here. The sample area appeared to have predominantly red paint, although it was heavily obscured by the surface darkening. The uppermost layer of dark material could be related to a discrete layer of soiling or coating, or we could be seeing black paint. Since the front surface of the figure is intricately painted, it’s difficult to completely rule out paint as a possibility. Aged coating materials often fluoresce in UV light, which can help to distinguish them from underlying paint layers. In this case, we can see small flecks of fluorescence (indicated by the red arrows) but not a distinct fluorescent layer. We can also observe faint fluorescence in the ground layer, which is consistent with the idea of an aged animal glue binder.

Another sample, X4, came from an area of plain red paint without any adjacent black designs. This area was also affected by the surface darkening issue, although to a less severe extent. Here, instead of a discrete layer of dark material, we can see small specks above the red paint layer (indicated by the red arrows). These dark specks are most likely related to soiling or discolored coating and unlikely to be original applied paint.

Sample X4, 200X total magnification, visible light (right) and ultraviolet light (left). Samples were viewed on a Zeiss Axio Scope.A1 polarized light microscope.

The cross-section samples offered some insights into the multi-layered nature of the delicately painted surface. As with most analytical techniques, results lead to more questions than clear-cut answers. Luckily, my colleagues here in the lab got together to talk about this complex condition issue and offer different perspectives and approaches. To clean or not to clean the darkened layer? Clarifying the surface details would be helpful for interpretation, but an even more gentle cleaning system will be needed to avoid damage to paint layers. The consensus: further testing needed!

Considering Cleaning

Julia Commander is a third-year graduate student in the Winterthur/University of Delaware Program in Art Conservation. She is currently completing a curriculum internship at the Penn Museum.

It’s time to check back in with the Ptah-Sokar-Osiris figure. In my last post, I mentioned a few of the condition concerns including a significant darkening over the front surface. The uneven surface poses interesting challenges for cleaning, and there are multiple approaches and methods to consider.

Before cleaning proceeds, it is important to understand both the nature of the surface discoloration and the properties of the paint layers. Egyptian objects are not always straightforward, and Ptah-Sokar-Osiris figures have a broad range of condition issues and treatment histories. Check out the British Museum’s online collection for a fascinating look at comparable figures. Discolored or yellowed varnishes have been observed on Egyptian painted surfaces, such as the shabti box described in a previous post. One way to assess surface discolorations is ultraviolet (UV) light illumination, a non-destructive lighting technique. In the UV portion of the energy spectrum, aged coating materials including varnishes and adhesives often fluoresce brightly. Areas that absorb more UV light appear darker in comparison. For this figure, areas of fluorescence do not appear to correspond to the pattern of discoloration, which is most noticeable on the platform under the feet.

L-55-29. In normal light (left), you can see the darkened surface of the front of the figure. In ultraviolet (UV) illumination (right), specific areas fluoresce. The pattern of UV fluorescence does not correspond to the discolored areas or suggest an overall coating.

Additionally, the surface darkening extends over large areas of damage and paint loss, suggesting that it occurred later in the object’s history. In an attempt to understand the darkened surfaces, I will take cross-section samples, which involve tiny (less than 1 mm) flakes of the paint layers. By looking at the edge of a paint flake under magnification, I can observe the stratigraphy from surface down to ground level. One way to visualize this technique is to think about slicing a cake to see the layers inside. To make handling tiny paint flakes easier, they can be mounted in resin for observation under magnification. Through normal light and UV light microscopy, the presence of discrete coating or soiling layers may be observed.

To characterize the behavior of the paint layers, solubility tests were conducted under magnification with small amounts of solvent on cotton swabs. For this painted figure, surfaces appeared to be water sensitive but relatively stable in other solvents. This finding is consistent with typical Egyptian paint binders such as gums or animal glues, which are both water sensitive. Once I know what affects the original surface, I will be able to think about designing a strategy to reduce darkening while avoiding disruption of the paint layers.

Dry surface cleaning is one of the first methods to test for a water sensitive surface. Cosmetic sponges and soot sponges lifted significant dirt and grime, although the appearance of the figure’s surface was not visibly improved. Water-based solutions and small amounts of solvent were tested in discrete locations to assess their efficacy. Water-based, or aqueous, cleaning solutions can be adjusted with buffers and chelators to more effectively lift dirt and break up staining. Chelators, such as citrate and EDTA (ethylenediaminetetraacetic acid) are complex ions that attach to metal ions, a key component of most types of dirt. A citrate solution at pH 8 was found to be very effective for lifting dirt and staining, but I wanted to minimize surface interaction with water. One method to manipulate these interactions is to work through silicone materials. Silicone gels, such as Velvesil Plus, can from stable emulsions that hold aqueous solutions. Silicone solvents, such as cyclomethicone D4, can saturate surfaces and act as a barrier layer to protect from water.

Testing dry surface cleaning with a cosmetic sponge on the figure’s base.

Testing aqueous cleaning solutions to reduce discoloration with a small cotton swab.

Could this be used as an overall cleaning solution? A larger test area suggested that the combination of materials, when applied carefully with brushes and worked over the surface, lifts dirt without visibly disturbing paint layers. However, the cleaning effect is slightly uneven, which raises concerns about whether this technique will significantly improve visibility and legibility of surfaces. Since this object is a long-term loan from the Philadelphia Museum of Art, continuing discussion with the PMA senior objects conservator, as well as Penn Museum curators, will help clarify these decisions.

In addition to aqueous cleaning methods, I researched the feasibility of laser cleaning. Conservators have successfully employed laser cleaning in many scenarios where discrete layers of soiling need to be removed from surfaces. For Egyptian artifacts, some of the primary challenges include fine control over complex surfaces and slight yellowing after cleaning. While the literature suggests that laser cleaning is unlikely to be the right solution in this scenario, we decided to experiment with a mock-up test panel to gain a sense of the technique’s future applications in the lab. This involved gathering typical Egyptian pigments, including the famous Egyptian blue and green, and mixing appropriate binders to mimic historic surfaces. The panel consists of an animal glue ground with gum arabic paint, coated with an additional layer of mastic varnish for half of the test areas. Mastic, a plant-based resin, is comparable to traditional Egyptian resins such as pistacia. After adding a little bit of “dirt,” a sticky mix of starch powder and pigments, I am ready to start exploring the efficacy of our laser cleaning system for painted surfaces.

Creating a mock-up panel to test laser cleaning on painted surfaces. Materials include Egyptian pigments mixed with gum arabic binder, an animal glue ground, and mastic varnish.

Selected resources:

Korenberg, C., M. Smirniou, K. Birkholzer. 2008. Investigating the use of the Nd:YAG laser to clean ancient Egyptian polychrome artifacts. Lasers in the Conservation of Artworks: 221-226. London: Taylor and Francis Group.

Larochette, Y. 2012. Wolber’s world: A review of a textile wet-cleaning workshop held in Oaxaca, Mexico. Western Association for Art Conservation (WAAC) Newsletter 34(1): 24-26.

Roundhill, L. S. 2004. Conservation treatment considerations for an Egyptian polychrome wood coffin. Objects Specialty Group Postprints 11: 89-102.

Ptah-Sokar-Osiris and Treating Painted Surfaces

Julia Commander is a third-year graduate student in the Winterthur/University of Delaware Program in Art Conservation. She is currently completing a curriculum internship at the Penn Museum.

As a conservation intern working in the Artifact Lab, I was able to go shopping through shelves of Egyptian objects and scope out interesting treatment projects. A painted wood statue, depicting the composite god Ptah-Sokar-Osiris, immediately caught my eye. The figure has intricate painted designs decorating the mummiform figure and its base, as well as gilded details in the face and headdress.

Ptah Sokar Osiris Statue, L-55-29A-C

L-55-29C, detail of paint and gilding

High-status burials in 19th dynasty Egypt often included this type of mummiform statue. Comparable examples of the popular object type exist in collections worldwide, such as the British Museum and the Metropolitan Museum of Art. Common characteristics include carved wood, a preparatory gesso layer, polychrome design, and in some cases, a coating of varnish. Ptah-Sokar-Osiris statues also frequently feature small compartments carved into the wood figure or base. These cavities could contain small papyrus scrolls or textile wrappings. While examining the object with this in mind, I noticed a faint rectangular shape on the reverse of the figure’s head.

X-radiography, a non-destructive imaging technique that helps clarify construction details, was perfectly suited for the question of the compartment. Without disturbing the delicate painted surface, we were able to observe that a rectangular cavity is in fact cut into the head of the figure. Although the cavity appears to be empty, this interesting construction detail is consistent with similar Ptah-Sokar-Osiris figures.

L-55-29A detail (left) and X-radiograph (right). Image captured from 55 kV, 2 mA, and 6 second exposure.

The statue has several condition issues, such as actively flaking paint and significant darkening over the front surface. Additionally, the figure is unable to stand upright in the base, and the components do not fit together securely. Upcoming treatment aims to address these issues, and I will be searching for the right approach to cleaning and consolidation. The complex surface made of wood, gesso, and paint will require detailed testing to find appropriate solutions.

To further investigate painted surfaces and possible coatings, I used multispectral imaging (MSI), which incorporates multiple light sources to reveal details that cannot be seen in visible light. Interesting findings included the presence of Egyptian blue in the figure’s wig and broad collar, as well as the headdress. This pigment shows up in visible-induced infrared luminescence and is easily distinguishable from surrounding pigments.

Detail of multispectral imaging, highlighting Egyptian blue pigment. Normal light (top), visible-induced infrared luminescence (center) with Egyptian blue shown in white, and false color image (bottom) with Egyptian blue shown in red.

Learning more about the object’s structure and surface will help inform treatment decisions about this complex figure. Check back to see what else we learn and how treatment will proceed!

Examination of Wooden Tomb Models

Hi everyone! This is Alexis North, and I’m the project conservator at the Penn Museum working on the Egyptian storage move project, which has been referenced here on the blog a few times. I wanted to give a brief introduction on one of the projects I have been working on most recently in the Artifact Lab.

We recently received several new objects in the Artifact Lab. They are a collection of painted wooden models, depicting various aspects of daily life, which date to the First Intermediate Period and Middle Kingdom (2130-1784 BCE). Many of the models we have were excavated by Sir Flinders Petrie and the British School of Archaeology, through excavations the University of Pennsylvania supported.

Photo of tomb models on display, prior to deinstallation.

Photo of tomb models on display, prior to deinstallation.

These models had been on display in our Egyptian Daily Life gallery for quite a long time. However, due to the vibrations caused by the construction going on right outside the museum, the entire case had to be deinstalled and the objects moved for their protection. The models have very fragile painted surfaces, and are made of multiple pieces which could separate, fall over, and be damaged if exposed to vibrations within the case. They also in most cases have not be examined by a conservator since their acquisition.

Therefore they were all brought into the Artifact Lab for documentation and treatment. We started by photographing all the individual pieces, and assessing the condition of the painted surfaces. Many of the models have actively lifting and flaking paint, and the horizontal surfaces are also quite dirty.

The model most in need of treatment is this boat:

Detail of E14260.1, boat model, before deinstallation.

Detail of E14260.1, boat model, before deinstallation.

Boats have a lot of significance in ancient Egyptian culture and religion. They were the primary means of long-distance travel along the Nile, and the Egyptians believed that the gods traveled across the sky and through the underworld on boats. Boats were also used for fishing. This model depicts a transport boat, with oarsmen, a mast and rudder, and a canopy painted in a cowskin pattern where the tomb owner would have been represented sitting and enjoying his travels.

This model has some of the most serious flaking paint and discoloration, especially on the top and sides of the boat:

Detail of lost and lifting paint on top of boat, and grimy surface.

Detail of lost and lifting paint on top of boat, and grimy surface.

I began treating this model by taking detailed photos of the surface, then using those images to map different condition issues. Then I chose different treatment materials and techniques which work best for those issues.

Come back for the next post to see more about what we learned from examining this model, and how I chose to treat it. See you soon!

 

References:

Fleming, S. (1980). The Egyptian mummy: Secrets and science. University of Pennsylvania.

Taylor, John H. (2001). Death and the Afterlife in Ancient Egypt. The University of Chicago Press.

 

Alexis North is the Project Conservator for the Egyptian Storage Move Project, Penn Museum.

 

X-raying fragments of a painted wooden coffin

I recently completed the treatment of these coffin board fragments.

E12617A-C, boards from a painted wooden coffin, before treatment

E12617A-C, boards from a painted wooden coffin, before treatment

In addition to the cleaning, which I blogged about before, the treatment involved stabilization of loose and powdery gesso and paint, filling losses where needed for structural support, and x-radiography, multispectral imaging, and portable X-ray fluorescence (pXRF) analysis. It has also enabled a translation of the text. I’m going to write a few shorter posts to highlight the different components of this project, starting with the x-radiography.

During my initial examination of the boards, I could see that the boards represent just a portion of the front, head end of the coffin. The rest of this side of the coffin would have continued much further to the left, but at some point these pieces were cut down and finished off on the left side to a smooth edge. This is most evident when you look at the hieroglyphic text, which obviously should continue to the left.

I could see that these 3 boards were originally joined with wooden dowels, because there are wooden dowels protruding from the join edges. I also noted some large cracks in the painted surface of the largest (center) piece in the image above, which led me to realize that this central piece was made of more than 1 piece of wood. I turned to x-radiography to get a better understanding of what is going on below the surface.

Here is a composite image showing the radiographs of the 3 boards:

E12617A-C x-ray image

E12617A-C x-ray image

The dowels joining the 3 pieces together are very clear in the x-ray image above. There are some darker (almost black) areas, which represent the holes that were drilled out for inserting the dowels. The denser (whiter) areas within those voids are the wooden dowels themselves. I’ve outlined these areas in green in the image below.

E12617xraymapped-1The x-ray image also helps clarify how the center piece is constructed, with 3 pieces of wood, which I’ve outlined in red above. Where those 3 pieces of wood join correspond directly with the cracks observed in the painted surface on the exterior.

Also visible in the x-ray image are two small nails driven into the lower edge of the bottom board. These nails are historic additions, likely added at the time when the boards were cut down and modified, although their purpose is unknown.

In my next post, I’ll focus on what cleaning, pXRF, and multispectral imaging has revealed about the painted surface, and I’ll include some after-treatment images.

 

Observations of a stola coffin lid

As if there is not enough up here (see our recent post about the Egyptian storage move and associated conservation work), this week we brought another quite large object into the lab, and it might be my new favorite object up here.

The lid of our yellow stola coffin

The lid of our* yellow stola coffin

This is the lid that belongs to the late 21st/22nd Dynasty yellow coffin base which we recently treated here in the Artifact Lab. Due to its previous location in storage, I hadn’t been able to take a close look at it until this week. Now that I’ve gotten to spend a few days with the lid, I’ll tell you that it’s total eye candy. If you were impressed by the painted decoration on the base, the lid will give you even more to get excited about.

I only just started to examine and document the lid and I will continue to update the blog as I work on this object, so today I’m just going to mention a few things about it, and some of my favorite details so far.

First of all, you may have noticed that I referred to this as a “stola” coffin in the image caption above. The term “stola” refers to the narrow red band depicted on the coffin that encircles the neck and crosses over the chest and over the oversize collar. Both the presence of the stola and the oversize collar have been recognized as distinctive of the late 21st/early 22nd Dynasty (see other examples and explanations here and here, and special thanks to Dr. Kara Cooney at UCLA for information as well).

The figure depicted on this coffin used to have a beard, which is now missing, but there is a hole in the chin indicating that it was once there.

Detail of the hole in the chin

Detail of the hole in the chin

The arms are depicted as being crossed over the chest and the hands are made of separate pieces of wood. The hands on this coffin are clenched and I have read that this is reserved for male coffins while females are depicted with hands open and lying on their chests. I’m assuming the fisted hands mean that this coffin belonged to a man, but I’ll have to check with our Egyptologists to confirm, since I cannot translate any of the text myself. I also really like the fact that the thumbnails are painted in:

Detail of the left hand

Detail of the left hand and thumb

What else can I say about it? Well, it is beautifully painted and also varnished just like the base with a yellow-colored pistacia resin. This pistacia resin causes many of the areas painted blue to appear green:

Much of the blue lines on the wig appear green, but in areas where there is no varnish, you can see the blue color of the paint.

Many of the lines on the wig appear green, but in areas where there is no varnish you can see the blue color of the paint.

There is a thick layer of dust on the surface of the coffin, but I can tell it’s going to clean up well. Check out the embossed details in this raking light image, which were built up with gesso:

Detail of the embossed designs on the central part of the lid

Detail of the embossed designs on the central part of the lid

This is going to be a fun object to work on! I’m looking forward to getting started with the treatment.

* I should clarify that this coffin technically belongs to the Philadelphia Museum of Art (PMA) but has been on long-term loan to us for nearly a century. We received this coffin as part of an exchange of objects between our 2 institutions in the 1930s. I am carrying out the treatment in close consultation with the conservators at the PMA.

Spring cleaning?

It may be a little early for spring cleaning, but no matter what time of the year, there is not much that I find more satisfying than a good, deep clean (on a grimy artifact). Last week, Tom Stanley (the museum’s Public Relations/Social Media Coordinator) posted this image on the museum’s Facebook page, which shows some cleaning in progress on an Egyptian painted wooden coffin here in the Artifact Lab:

coffin board cleaningHe also posted this on our Instagram page.

Here is a before treatment image of the coffin board (which is in 3 separate fragments):

E12617A-C, boards from a painted wooden coffin

E12617A-C, boards from a painted wooden coffin

While Tom was in the lab taking photos, I promised him that I’d put some additional information about this project on the blog. I thought this would be a great opportunity to take another video with our binocular microscope, kind of like the video I captured of the paint consolidation on the shabti figures I worked on awhile ago.

To see the process of how we go from

————————–this————————–to————————–this———————-

corner before after

click on the link below.

Cleaning an Egyptian painted wooden coffin from Molly Gleeson on Vimeo.

In the video, you’ll see (at 7.5X magnification) that I first used a soft-bristled brush to remove loose sediment and dust from the surface, by brushing directly into the nozzle of a variable suction HEPA-filtered vacuum. Then I used a cosmetic sponge to further, gently, lift away grime from the surface. Finally, I used a kneaded rubber eraser to remove the grime that is more embedded in the painted surface.

Okay, so I’ll admit that this may not be as cool as the video of Conservator Tessa de Alarcon laser cleaning a stone table from Ur (this one is hard to top), but it’s pretty gratifying nonetheless.

I’m currently trying to learn more about this object too, by checking into our museum records. I’ll keep you posted.

Putting the finishing touches on the shabti box

I have put a lot of work into our troubled shabti box, including investigating and analyzing the varnish (more on the analysis in an upcoming post), doing some pretty cool imaging, and consolidating all flaking and unstable varnish and paint with methylcellulose. After consolidation of the surfaces, the box does not look much different than it did when I started the treatment (and this is a good thing). As a reminder, here is an image of the front of the box before treatment:

shabti box frontAt this point, I could call the treatment done, or take it a step further, by filling in some of the losses of the painted surface, which appear bright white since those losses expose the gesso below. After consulting with Dr. Jen Wegner in the Egyptian Section and with Lynn Grant, the head of our department, I decided to fill in some of the larger losses which really make it difficult to appreciate the object and “read” the designs. I have even heard some visitors refer to the box as “that badly damaged piece of wood”, and that is not what we want people to be thinking when they eventually see this on display. While I know I can never return the box to its original condition, I can reduce the appearance of some of the damage. But how to fill the losses on such a fragile surface, in a way that will be reversible/retreatable?

After some hemming and hawing and some failed tests, I ultimately decided to fill the losses by first placing a small piece of Japanese tissue paper into the loss, then applying a tinted fill mixture over the paper. I did this by doing the following:

1. I took a quick snapshot of the surface I was about to work on. I then downloaded the image and copied it into a Word document. Using the scale in Word, I was able to resize the photograph in order to print it approximately true to size, and then I printed the image in black and white. This took no more than 5 minutes.

2. I placed a piece of Mylar over the B&W print-out and traced the losses I wanted to fill with a black marker.

L-55-23A_template2

B&W image with Mylar template moved off to the right side

3. After trimming the Mylar around one of the tracings, I taped it to a piece of Japanese tissue paper with a small piece of blue tape.

L-55-23A_template34. I cut out the Japanese tissue paper and adhered it into the loss on the shabti box with a small amount of 5% methylcellulose.

5. I then applied a fill mixture over the Japanese tissue paper. The fill mixture is made of 5% methylcellulose, glass microballoons, and powdered pigment.

Fill mixture (in the jar and on the spatula)

Fill mixture (in the jar and on the spatula)

This may sound tedious, but the whole process works very smoothly and relatively quickly. It also minimizes the amount of time I need to spend touching the object and therefore minimizes damage that might be caused by touching the very fragile surface.

I’m not finished, but so far I’m pretty happy with how the front of the box is looking:

L-55-23A_dt01_compressed

Front view, during filling

It’s subtle, but to see the difference that filling makes, here are views before and after, side-by-side:

Picture1

Before treatment (left) and during treatment (right)

The only problem is, I feel like I’ve opened a can of worms. There are so many losses and I am not going to fill them all, but as soon as the larger losses are filled, I start seeing all of the small ones! I think it’s looking better though and I will get some feedback from my colleagues before proceeding further.