One of the earliest known forms of writing is cuneiform, a wedge-shaped script developed by the Sumerians, around 5000 years ago. It is preserved on stone carvings and clay tablets. The survival of the clay tablets is amazing, given that most were of unbaked clay – essentially mud. Today’s Conservation Confidential (1 pm EST on Penn Museum’s Facebook page) will feature conservator Tessa de Alarcon discussing the preservation of these earliest written records.
By Tessa Young
Who doesn’t love a beaded necklace? They’re sold commonly today, but did you know that they were popular in the Ancient Middle East? There are a number of fabulous pieces of beaded jewelry on display in the new Middle East Galleries, and several beaded items from our collection will be featured in the Museum’s Jewelry of Ur lecture and workshop scheduled for June 14th!
Excavation of a Bronze Age necklace from a burial in the UK (Credit: Suffolk County Council Archaeological Service Contracting Team and Persimmon Homes Ltd [Anglia]) (https://www.futurity.org/shells-necklace-bronze-age-718992/)
B15918 before treatment, with a broken strand and hasty repair tying off the ends
Here at the Penn Museum, when beadwork is destined for loans, display, or requires handling for programming, the Conservation Department wants to be sure that these objects are secure. For the upcoming Jewelry of Ur program, fellow conservation technician Alyssa Rina and I were tasked with restringing several pieces of beaded jewelry, including B15918, pictured above. The floss on this piece was previously broken and then tied off in a quick repair. The plan for this conservation treatment was to restring the beads in a loop with a more durable floss.
Depending on the piece, we restring using two different weights of braided nylon floss, which has the strength necessary to hold the beads securely while also being capable of holding knots. Monofilament (fishing line) is another popular choice, but we have found that knots can come undone rather easily with this material.
Restringing beads in a padded box using a needle in the artifact lab
Penn Museum Conservators have developed several tactics to keep the beads in place during the restringing process. First, we always keep the beads contained within a padded box, preventing the beads from rolling away and getting lost. Second, as seen in the photograph, we typically use a small clamp to secure the floss to the edge of the box. This keeps everything from shifting and rolling around. Finally, we thread the floss onto a small needle to aid in the efficiency of stringing the beads. These beads had large and regular enough holes to use a standard sewing needle, but thin, flexible beading needles are also an option.
Conservators also want to be sure that the stringing will remain in place. The first bead on the string is tied into place with two half-hitches (more-or-less a fancy double knot), and then the rest of the beads are strung into place with the help of a thin, flexible needle. If the beadwork is supposed to be a loop, at the end of the strand, the floss is threaded back through the first bead, and again tied off with two half-hitches. If the beadwork is supposed to be linear, the terminal bead is tied off with two half-hitches, making sure that the beads are tight but comfortable on the strand. Once this is done, the beads are stable enough to be handled or put on display without any fear!
B15918 after re-stringing
By Marci Jefcoat Burton
As a last installment of the mosaic column from Tell al-Ubaid in Iraq, we are pleased to announce the treatment and remounting of the 4,200(+) year-old shell, pink limestone, and black shale tesserae is complete (Figure 1)! After a number of years in collection storage, the recently conserved column is now in the Middle East Gallery, and ready for visitors when the exhibit opens this Saturday, April 21, 2018. The treatment process was a dynamic collaborative project, involving a team of seven conservators to clean, repair and re-mount hundreds of triangular and diamond shaped tesserae over the span of 18 months.
Figure 1: The previous column support (left), with all tesserae deconstructed from each section. Only mounting materials, such as plaster ground and reconstructions, remain on the supports. (Right) The newly mounted tesserae on Ethafoam column supports.
The tesserae were originally mounted at the archaeological site in 1919 – 1924 on four hollow cylindrical sections made of wire mesh and burlap. The tesserae were imbedded in a thick layer of plaster, and the resulting weight on a somewhat flexible base eventually became a structural problem. In addition, each column section had a large area of plaster reconstruction to continue the mosaic design around the column. For a memory refresher of the previous condition and treatment protocol, visit our blog posts, column blog 1 and column blog 2.
After months of cleaning every tessera and adhering many fragments back together, the tesserae were mounted onto a new support made from solid Ethafoam, a chemically stable and dense foam (Figure 2). Each new column section support was reconstructed to the same measurements as the wire mesh and burlap supports. The previous use of plaster proved too rigid and heavy in the original mounting system, causing many cracks to develop in the plaster and tesserae to loosen over time. For these reasons, plaster was not used again, and the tesserae were mounted to the Ethafoam supports with an acrylic paste (Paraloid® B-72 (ethyl methacrylate (70%) and methyl acrylate (30%) copolymer) in acetone bulked with glass microspheres) toned black with dry pigments. This is lighter in weight compared to plaster, and compatible with the shell and stone materials. The black acrylic paste was made to resemble bitumen, a pine resin material used by the Mesopotamians to originally mount the tesserae to the c. 3rd Millennium BCE column.
Figure 2: Mounting process of column section #2. The cleaned and repaired tesserae are mounted to the Ethafoam cylindrical supports with Paraloid® B-72 (ethyl methacrylate (70%) and methyl acrylate (30%) copolymer) in acetone bulked with glass microspheres and toned black with dry pigments to mimic bitumen. Spatulas were used to spread the acrylic resin on the support and tesserae were imbedded into the mixture.
All four column sections stack and connect with an internal wooden dowel system. To accommodate the large areas that were once plaster restorations, our Photo Studio printed high resolution, archival images of the tesserae, which were custom scaled and fit to each column section (Figure 3). The digital photo fills integrate a complete mosaic design to give the appearance of a fully mosaicked column (Figure 4). This is a great example of how recent technological advancements help conservators with approaches to treatment and display options.
Figure 3: (From left), Conservation Interns Tessa Young, Alyssa Rina and Jennifer Mikes installing digital photo fills to the top and bottom mosaic column sections.
Figure 4: (a): Column section #2, after remounting tesserae. The locations with previous plaster reconstructions are padded with Volara (closed-cell polyethylene foam). (b): Column section #2 after pinning archival photo fill into place over the Volara.
The mosaic column, and over 1,500 objects await your visit in the Middle East Galleries (Figure 5)! To our visitors in the Artifact Lab who witnessed our many, many hours of treating these column sections, we thank you for your brilliant questions, comments and curiosity about the tesserae and our conservation process during our Open Window Sessions. You will find the assembled column has transformed into an impressive and complete piece, and we hope you enjoy it as much as we do!
Figure 5: Bob Thurlow (Special Projects Manager) and Marci Jefcoat Burton (Conservation Curriculum Intern) installing the four mosaic column sections in the Middle Eastern Gallery.
Our new Middle East Galleries open next week and they will feature over 1200 artifacts from our collection, including many iconic objects like the Ram in the Thicket, the Bull-headed lyre, and Queen Puabi’s headdress. Oh, and for those of you who are always asking about our cuneiform tablets, do we have a treat in store for you – there are dozens and dozens in the galleries. The majority of the objects in the exhibition were excavated by Penn archaeologists, many nearly a century ago.
ALL of these objects came through our Conservation Labs to prepare them for the galleries and many needed significant treatment in order to ensure their stability for long-term display. Our Middle East Galleries (MEG) team has worked diligently and tirelessly on this project – you can read more about some aspects of this work on the Penn Museum blog here.
The triumphant column team poses next to the 4 recently conserved mosaic column drums from Tell al-‘Ubaid, Iraq. This project took months to complete.
In just over a week, visitors to the Museum will have the opportunity to get up close and personal with these newly-conserved objects. Everyone will be drawn to the highlight pieces mentioned above and here, but the other pieces are worth lingering over too. It’s usually impossible to see them as closely as we do during the conservation treatment process, so I thought I’d give you the opportunity to see 2 small but beautiful objects closer than you can in the galleries.
B8997 (left) and B9026 (right)
These 2 female figures, both excavated from Nippur, Iraq, will be on display in the same case in the Middle East Galleries. They’re small, just several inches long. The figure on the left was likely a doll which would have had articulated arms; you can see the holes where they were once attached. Fortunately, both artifacts required very little treatment. B8997, the figure on the left, does have a large, but stable crack that did not require any treatment. Examination under the binocular microscope revealed small amounts of burial dirt on both figures which had escaped previous cleaning campaigns, so both were carefully surface cleaned to remove this soil.
Detail of B9026 before (left) and after (right) cleaning, 7.5X magnification
As I worked on these figures, I captured some images with the camera attachment on our Leica microscope. Both objects are made of bone and are delicately carved. The reverse side of the doll’s head has an unworked area that nicely shows the cancellous (or spongy) bone features.
B8997 detail of front (left) and reverse (right), 7.5X magnification
Their time in the lab was brief – they only stayed for a day or 2. But in the midst of the hustle and bustle of preparing for these galleries, it’s nice to take a moment to appreciate the details.
The Middle East Galleries open to the public on Saturday, April 21. Our department has a few loose ends to wrap up with that project (and a few loose ends on the blog – stay tuned for a last blogpost on the mosaic column treatment) but we’re already turning to our next big tasks – the renovation of our Mexico & Central America Galleries, Africa Galleries, and Egyptian Galleries.
The transforming treatment of the Al’Ubaid frieze of three birds (B15883) from the new Middle East Galleries in now complete! (To be more correct, they are probably doves not ducks.) More information about the frieze can be found here. Click here for more information on the exciting new galleries, opening this April!
The frieze before treatment
The frieze after treatment
Originally, the three stone birds (initially called ducks but now identified as doves) would have been surrounded by black shale tesserae and the borders would have been copper alloy sheets. The frieze would have originally looked much like the marching bulls frieze. Unfortunately, neither the shale pieces nor the copper alloy borders made it. The birds had been embedded in a plaster background carved to look like the shale tesserae, and the borders were made from modern machined copper alloy sheets.
The old support system had to be removed due to some condition issues and to prepare the frieze for long-term exhibition. Once taken off, the grimy birds could then be laser-cleaned. The blog post about laser-cleaning them can be found here.
Applying the bulked Paraloid B-72 to the Ethafoam© support
Although the only ‘real’ parts were the stone birds, the curator wanted the entire frieze to be reconstructed to help visitors put the birds in context. It will be displayed next to the marching bull frieze.
After cleaning, the birds were adhered onto a piece of dense archival foam. The black tesserae background was created with Paraloid B-72 (ethyl methacrylate and methyl acrylate copolymer) bulked with glass microballoons and toned with dry pigments. Bulked Paraloid B-72 is stable, reversible, and easily manipulated with either solvent or heat. The shallow lines to make it appear there are tesserae were put in with a heated spatula. The copper alloy borders were also created with Ethafoam© coated in bulked Paraloid B-72 tinted in various shades of green to mimic copper corrosion. The fills in the ducks were inpainted with acrylics to integrate them better.
After all that, the ducks look much happier!
The frieze after treatment and ready for display
By: Céline Wachsmuth
It’s Tuesday and that means it’s time for another transformation story. This one comes from an object going into the Middle East Galleries (click here for more information on the exciting new galleries, opening this April!).
It’s hard to believe the first month of January is almost over! Many people make resolutions for the New Year, hoping to make an improvement, big or small (myself included, I have a Google doc with a list of resolutions). Most resolutions are easier said than done, including the prevalent resolution to shave a few pounds. This bowl had similar thoughts, but made losing some weight look like a piece of cake!
Bowl before treatment (left) and after treatment (right)
This bowl had been repaired in the past, but the joins needed to be taken down because the old adhesive was failing. The bowl was pretty clean when it came into the lab so it wasn’t long before I began solvent testing the adhesive in order to make a vapor chamber. The adhesive was soluble in acetone and most of the sherds separated with gentle prodding after eight days in a vapor chamber. The old fills (made of plaster), however, did not budge. This was probably due to the likelihood that they had been cast in place.
Outlines of Old Fills
Fill outlined in dark blue was dremeled out
Fills outlined in light blue were softened with deionized water and then removed
These ounces had to go! When a fill resists detachment by solvent, other, usually mechanical, methods have to be implemented. One mechanical treatment is to use a dremel, just like the one you might use at home for some smaller detailed work, to carve away the fill. This is tricky because the dremel can put the object at risk if used improperly. Once I was all set up and had been shown the proper technique, I slowly moved around the entire area of the fill.
using the dremel to remove the fill
two of the sherds sitting in a bed of glass beads while the adhesive sets
Once the large fill was removed and those ounces had been shed, it was time for some TLC. I cleaned the break edges on each sherd with acetone (for the sherds previously joined with adhesive) or deionized water (for the sherds adjacent to the old fills). All the break edges were then coated with a dilute solution of Paraloid B-72 (ethyl methacrylate methyl acrylate copolymer) and the sherds were put back together with a 50% solution of Paraloid B-72 in 1:1 acetone:ethanol. Two small areas of the bowl had some gaps that needed to be filled; one for added structural stability and one to help complete the shape. This was done using a mixture of 3M microballoons, Paraloid B-72 in 1:1 acetone:ethanol, acetone, and some dry pigment to approximately color match the fill to the bowl. The fills needed some additional color to help blend in more and they were painted with light washes of acrylics.
This bowl made losing a couple ounces look easy even though we all know how much work really has to go in to something transformative! Thankfully, it’s only the beginning of the year and there is plenty of time to make your own transformations. Just like there’s plenty of time for another transformation to happen in the labs before our next Transformation Tuesday post – stay tuned!
PS – If you’re looking for some “ancient workout tips” check out these fun suggestions
By Marci Jefcoat Burton
As a follow up to my previous blog post, conservation treatment of the second of four sections comprising a mosaic column from Tell al-Ubaid, Iraq is well on its way! For a quick recap, the column is dated to 2400 – 2250 BCE (Figure 1). After centuries of burial, the triangular and diamond shaped shell, pink limestone, and shale tesserae (also referred to as tiles), were excavated in 1919 – 1924. The original wooden column interior did not survive the centuries of burial, so after excavation, the tesserae were mounted with plaster to four hollow cylindrical supports of metal mesh covered with burlap. After nearly 100 years, shifts in the internal support have caused structural instability to each section.
Figure 1: (left) Before treatment image of the four column sections stacked together to make a complete column. Image courtesy of The Metropolitan Museum of Art. (2003). Art of the First Cities: The Third Millennium B.C. from the Mediterranean to the Indus. The Metropolitan Museum of Art: New York) (right) Column section 2 detail, before treatment.
First step of treatment: Remove tesserae from the current support.
The plaster was softened with distilled water applied by brush, then carved away to expose the sides of the each tessera. The tesserae could then be separated from the plaster and burlap backing one by one (Figure 2). Like the first slice of pie, the first piece was the most difficult to remove. Once extracted, access to adjacent tesserae became easier.
Figure 2: (left) Removing plaster surrounding the tesserae with a scalpel blade. Plaster was first softened with distilled water. (middle) Carefully extracting a shell tessera from the plaster. (right) Shell tessera after removal from column section.
The tesserae were removed from the support and placed on an enlarged reference photo in a tray to maintain the order of composition (Figure 3).
Figure 3: All tesserae were removed from the support and placed on top of a rolled out image of the column section to maintain their original placement. All that remains on the exterior of the cylindrical support is a layer of grey plaster and previously filled areas. As a bonus, the Egyptian female child mummy named Tanwa can be seen in the background, just outside of the Artifact Lab window!
Second step of treatment: Cleaning
After removal from column section 2, all tesserae were covered with a layer of powdery plaster, which was removed with distilled water applied with hand-rolled cotton swabs. Medical scalpels were used to gently lift and remove thick remnants of plaster as well as adhesive from previous repairs. In addition, years of dark-brown dirt, dust and grime were removed with distilled water, and Stoddard solvent (a petroleum-derived organic solvent) was applied to the pink limestone and shell pieces to remove greasy grime trapped in the surface (Figure 4).
Figure 4: (left) Removal of adhesive and plaster remnants from a diamond shaped tesserae using a medical scalpel. (right) Shell tesserae being cleaned with distilled water. Note the dark grey-brown grime picked up on the cotton swab.
Third step of treatment: Repair
Once cleaned, tesserae that exhibited breakage such as cracks, detachment, and delamination were repaired with a thin layer of a semi-viscous solution of Paraloid® B-72 (ethyl methacrylate (70%) and methyl acrylate (30%) copolymer) resin in acetone. The majority of the shell tesserae experienced separation between the layers comprising the shell. Some even separated into several pieces, making their reassembly somewhat of a puzzle (Figure 5)!
Figure 5: (left) A triangular shell tessera delaminated (separated) into six pieces. (right) The same shell tessera with all pieces adhered together with Paraloid® B-72.
The shale was even more temperamental to remove from the column section (Figure 6). Shale is a soft sedimentary rock composed of mud, clay, and minerals, such as calcite and quartz. The inherent nature of the shale causes breakage and crumbling. Water can remove particles from the shale surface, therefore these pieces were cleaned with dry brushes and if needed, cotton swabs lightly dampened with distilled water.
The most resilient material was the pink limestone. While some pink limestone tesserae are weathered on the surface, most likely from centuries of burial, these tiles exhibited very little breakage and cleaned up nicely with distilled water and Stoddard solvent (Fig. 6).
Figure 6: (left) A diamond shaped shale tessera exhibiting a lack of cohesion, best observed around the edges, which caused cracks and areas of material loss. (right) A resilient triangular pink limestone tessera with a weathered surface, noted by the lighter, speckled locations. The pink limestone tesserae have strong cohesion and required very little repair.
After a month of cleaning and repair of the shell, pink limestone and shale tesserae, their overall appearance is quite transformative. The tesserae look brighter and truer to their original colors (Figure 7). This is especially the case for the pink limestone, which went from a dark peach-brown, to a brighter light-pink hue.
Figure 7: (left) Shell, pink limestone and shale tesserae after removal from the former support, and kept in their original arrangement. (right) All tesserae after cleaning and repair, ready for re-mounting to a new support.
…..What’s next?
The next phase of treatment for section 2 of the mosaic column is to mount the shell, pink limestone, and shale tesserae to a new solid cylindrical support. More information and updates on the column treatment progress will be featured in an upcoming post, so please stay tuned!
On November 1, our Museum announced the commencement of our Building Transformation campaign, a monumental project which will include a full renovation of our building structure and reinstallation of many of our signature galleries, including our iconic Egyptian Galleries.
The first glimpse of this work will be the opening of our Middle East Galleries in April 2018. This is not news for readers of this blog – you have been hearing about the conservation work for this project for awhile now (for reference, see these related blogposts).
Graduate intern Marci Jefcoat Burton (standing) and pre-program interns Fallon Murphy, Jennifer Mikes, and Alyssa Rina during an open window session in the Artifact Lab (with one of the al-Ubaid mosaic columns in the foreground)
In fact, you can get a glimpse of several exciting projects that are underway for our Building Transformation right now, on a daily basis, in either of our 2 public conservation labs.
In the Artifact Lab, you will mostly see objects being conserved for the Middle East Galleries and for our Mexico and Central America Gallery, opening in November 2018.
An assortment of artifacts for the Mexico and Central America Gallery in various stages of conservation treatment.
Our other public lab is down in our Lower Egyptian Gallery. Work in that space is dedicated exclusively to conservation treatment of the carved and painted limestone blocks from the Old Kingdom tomb chapel of Kaipure.
A view of the Kaipure tomb chapel lab space in Lower Egypt
Project Assistant Anna O’Neill at work on a block in the Kaipure lab
While you can watch the conservation team at work most days in the Kaipure lab, unlike the Artifact Lab, it does not include open window sessions. But have no fear – the Kaipure team has promised to write some blogposts about aspects of their work, so stay tuned for more information on this project!
Big projects like the Building Transformation campaign come down to a lot of little details, and no one knows details like the Conservation Department. We hope you visit us to learn more about these details, and all the work underway to make these big changes possible.
Sometimes you just can’t get close enough (intern Celine Wachsmuth in the Kaipure lab)
To learn more about the vision of our Building Transformation, check out this ~3 minute video which captures the grandeur of the project (and features Project Conservator Tessa de Alarcon!).
Marci Jefcoat Burton
My first project as a curriculum intern with the Penn Museum Conservation Department involves the conservation of a mosaic column from the Ninhursanga temple site of the ancient Mesopotamian city of Tell al-Ubaid in Iraq (column in digital collections: (B15887.1 – 15887.4). Dated as 2400 – 2250 century BCE, the column was excavated sometime between 1919 – 1924 as a pattern of alternating triangular and diamond shaped shell, pink limestone and shale tiles. Fortunately, the years of resting in the compacted dirt of the burial environment preserved the shell and stone tesserae and maintained their original conformation. The original column interior, more than likely palm logs, did not survive the centuries of burial.
Figure 1 (left): Before treatment image of the four column sections stacked together to make a mosaic column.
Figure 2 (right): Reconstructed façade of the Ninhursanga temple of Tell al Ubaid. The columns were originally believed to be outside the entrance of the temple doorway, although it is not certain if both columns were on the exterior or interior of the building. (Both images courtesy of The Metropolitan Museum of Art. (2003). Art of the First Cities: The Third Millennium B.C. from the Mediterranean to the Indus. The Metropolitan Museum of Art: New York)
Without a support, the delicate tesserae were lacking a method of storage and display. Working with the materials available on site and with technology available in the early 20th century, the archaeological team constructed four drums to mount the tesserae into four stackable sections. Although reports attribute the original 3rd century BCE binding medium as bitumen (i.e., asphaltum, tar, pitch) to hold the tesserae in place on the original wooden supports, the 20th century excavation team reconstructed the shell and stone mosaic pieces with a grey plaster. In addition, only half of each drum holds original tesserae, and the remainder of each section is filled with a painted plaster reconstruction.
Figure 3: c. 1920s, on-site with the recently assembled tesserae onto the wire mesh and wood drums. (Image courtesy of http://www.mesopotamia.co.uk/tombs/story/page07b2.html).
X-radiography of one of the drum sections revealed that each drum is constructed as a hollow metal mesh cylinder with wooden caps on each end, and several nails to keep the cylinder together. After 100 years in this conformation, the drums have become problematic for the long-term display of the tesserae. Fluxuations in temperature and humidity, as well as the weight of the tiles and the thick, rigid plaster have caused opposing shifts in the internal structure, leading to the formation of cracks in the plaster and several tiles to dislocate and fall from the support.
Figure 4: X-radiographs of column section B15887.3 detailing the inner drum structure consisting of an open wire mesh and hollow interior. (Left (a)): X-radiograph of the column section side reveals the radiopaque grid pattern indicative of a metal mesh. (Right (b)): X-radiograph of the column section top, revealing numerous nails in various locations that hold the cylindrical drum together. (X-radiographs courtesy of Julia Commander (2016)).
The column, with all four sections, is one of the many objects selected for exhibition in the upcoming Middle Eastern Gallery (scheduled to open in Spring 2018). Therefore, it was decided it was time for the over 4,000 year old tesserae to be removed from the hollow wire mesh supports and then remounted onto a structured, solid support made with materials that will prevent structural damage and be sustainable for its preservation and long-term display in the gallery. Following a treatment protocol implemented successfully on one of the four column sections by Julia Commander (WUDPAC, Class of 2017), I will deconstruct the tesserae from the current supports, clean and repair each piece, and remount the tesserae in their same arrangement to new cylindrical supports made from solid, very dense Ethafoam measured to the exact shape for each section awaiting treatment. Stop by the Artifact Lab to see the progress of the column treatment, which is already underway, or stay tuned for a follow up blog post!
Figure 5: Start of the disassembly of the shell, pink limestone and shale mosaic tesserae from column section 2. Note the color difference of the large painted plaster fill on the left versus the original tesserae on the right. Several breaks are also observed in the inlays (most notably the beige shell pieces) and a layer of dark, brown grime has accumulated on the surface overall.
In addition to the frieze of 6 bulls (which we are still working on in the Artifact Lab), we are also treating a frieze of 3 birds, in preparation for our new Middle Eastern Galleries, scheduled to open in April 2018.
B15883, frieze of 3 birds before treatment
This is a section of a frieze from the site of Al-Ubaid, Iraq which was excavated by Sir Leonard Woolley in the early 1920s. The birds are the only original pieces of the frieze – the rest is a modern reproduction. The birds (possibly doves?) were carved from limestone and each has a pair of drill holes at their center which would have served as an attachment point. Copper alloy twists would have been used to secure the birds in antiquity – fragments of the original copper remain in one of them.
Due to structural stability issues in the modern reproduction, we needed to disassemble the entire frieze. Once the birds were removed, it was evident that their surfaces were very grimy, related to both the burial environment and time in museum storage. A variety of cleaning methods were explored and tested, but none worked better than using our laser.
One of the birds, after removal and before cleaning
The Conservation Department purchased a Compact Phoenix Nd:YAG laser several years ago, and we are still learning about all of its possible applications. We recently had a workshop with conservator and laser-guru Adam Jenkins, which helped us further develop some testing and health and safety protocols.
Essentially, the Nd:YAG laser works like this: the laser emits a beam of light, typically with a wavelength of 1064 nm (in the infrared), which selectively irradiates and removes unwanted dirt and surface coatings without damaging the object (a process called laser ablation). This type of laser cleaning works well for removing dark substances from light-colored objects, so trying it on one of the birds made a lot of sense.
Easy for me to say. I didn’t do this treatment – project conservator Madeleine Neiman did. So she gets all the credit for this.
After testing, Madeleine carried out her first laser cleaning treatment on the bird in the image below. Here she is getting set up to carry out the work:
And here is a shot of the bird after the surface was partially cleaned: (WOW!)
I think the process and results are best displayed in a gif, or a video, so I’m including the gif below, and here is a link to the video.
Go Madeleine! I think this was a really rewarding treatment to carry out. Please take note of all of the PPE (personal protective equipment) involved, including special eyeware and ventilation.