As with the XRF analysis, we were able to perform FTIR using portable equipment belonging to Pratt Institute.  Eleonora del Federico, Associate Professor of Chemistry in the Math and Sciences Department at Pratt Institute brought her portable FTIR device to our paper conservation lab.

We decided to use FTIR for two reasons.  One is we want to know if the ancient Egyptians used an adhesive to attach separate sheets of papyrus to form a long continuous scroll.  We can see the joins where one sheet was attached to the next but it is unknown whether an adhesive was used to hold them together.  Note the dark vertical line towards the far left of this image of papyrus in transmitted light; this is where two sheets of papyrus have been joined together.

Two joins exist on this fragment, one towards the right side and one towards the left side of the piece. Samples were analyzed on areas of joins and non-joins in order to make a comparison.

Secondly, we want to try and identify the binder in the pigments used to write on and illustrate the Book of the Dead.

FTIR uses infrared radiation to observe the vibrational changes in chemical bonds in order to identify certain functional groups.  From this information, certain types of materials can be identified as protein-based, cellulose-based, etc. and this can help us to determine if an adhesive is present.

The FTIR device scans a tiny area over and over again to capture the vibrational changes.  Here you can see the FTIR scanner placed under the papyrus.  The infrared rays are directed upwards to scan the area to be analyzed.  For this analysis, each scan lasted around 5 hours, amounting to over 20,000 scans for each area.

Combined, the information from these scans provide data which is viewed in the form of spectra, with many bands that represent chemical bonding between two particular atoms or a group of atoms in a molecule. The spectrum will be compared to a set of known reference materials for identification and interpretation.

We think it is possible that the ancient Egyptians used an adhesive to join the individual sheets to form a roll.  If they did, it is likely that they used a protein-based adhesive such as animal glue, or a starch-based adhesive such as wheat starch paste.  It is also possible that no adhesive was used, and that moisture was used in the same way that it was used to join the strips to form a sheet (see previous blog entries on making papyrus).  In the latter case, moisture would be used along with extreme pressure to form a physical bond to join the sheets.  We also think that the binders used with the pigments on this scroll could likely be gum arabic or animal glue. We are still awaiting results for our analysis.

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This post is part of a series by Conservators and Curators on papyrus and in particular the Book of the Dead of the Goldworker of Amun, Sebekmose, a 24 foot long papyrus in the Brooklyn Museum’s collection. This unique papyrus currently in 8 large sections has never been exhibited due to condition. Thanks to a generous grant from the Leon Levy Foundation, the entire papyrus is now undergoing conservation treatment. The conservation work is expected to last until fall 2011 when all 8 sections will be exhibited together for the first time in the Mummy Chamber. As each section is conserved, it will join those already on exhibition until eventually the public will see the Book of the Dead in its entirety.

Fragment from Book of the Dead of the Goldworker of Amun, Sobekmose. Egypt, from Saqqara. New Kingdom, Dynasty 18, probably reign of Thutmose III to reign of Amunhotep II (circa 1479–1400 B.C.E.). Papyrus, ink, pigment, 14 x 288 2/3 in. (35.6 x 733.2 cm). Brooklyn Museum, Charles Edwin Wilbour Fund, 37.1777E

XRF is used to identify most elements with an atomic number on the periodic table equal to or greater than Aluminum.  Most importantly, the technique can be used without any harm to, or even contact with the art object.  For these reasons, art conservators use the technique to help them identify what elements are present in a targeted area of an object.

XRF uses x-rays to determine the area in question.  The spectra that are captured during each reading show peaks representing the x-ray’s energies for each element present.This image is an example of the spectra provided by XRF.  The characteristic peaks identify the elements and the height of the peaks can determine the quantity of each material present compared to other elements.

In the case of this papyrus scroll, we wanted to come to a better understanding of what inks the ancient Egyptian scribe used to write the spells for this Book of the Dead, and what pigments he used to illustrate it.

Fortunately for us, Eleonora del Federico, Associate Professor of Chemistry in the Math and Sciences Department at Pratt Institute, along with many of her students, also has a keen interest in studying papyrus and ancient Egyptian pigments.  Her department has a portable XRF device, which they brought to our paper lab on several occasions in order to perform the analysis with us.

This is what Pratt’s portable XRF device looks like.  Here is it seen mounted to a tripod and positioned just a few millimeters over the pigment we want to analyze.  When the device is turned on, x-rays are emitted from a tiny tube and directed towards the object.  These x-rays are capable of measuring an area just a few microns in diameter.

The first scan we did was on an area of red pigment in the vignette towards the right edge of the papyrus fragment (see arrow).

The XRF was positioned over the object and after a few minutes enough data was gathered for interpretation.

The results show a large peak of iron, which suggests that the pigment is an iron-based pigment such as red iron oxide.

We repeated this process several times in other areas on this fragment and the following pigments were indicated:

Red – red ochre
Yellow – yellow ochre
Green – malachite
Blue – Egyptian blue
Black – carbon black

These findings are consistent with the pigments that we know were available and often used by the Ancient Egyptians (see previous blog, Pigments and Inks Typically Used in Papyrus).

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This post is part of a series by Conservators and Curators on papyrus and in particular the Book of the Dead of the Goldworker of Amun, Sebekmose, a 24 foot long papyrus in the Brooklyn Museum’s collection. This unique papyrus currently in 8 large sections has never been exhibited due to condition. Thanks to a generous grant from the Leon Levy Foundation, the entire papyrus is now undergoing conservation treatment. The conservation work is expected to last until fall 2011 when all 8 sections will be exhibited together for the first time in the Mummy Chamber. As each section is conserved, it will join those already on exhibition until eventually the public will see the Book of the Dead in its entirety.

Papyrus is a perennial freshwater plant which favors marshes and swamps.  It grows best in shallow water along the edges of sheltered fresh water bodies, which is why the banks of the Nile are an ideal location for growing papyrus.  Fortunately, we are located next door to the Brooklyn Botanic Garden, where papyrus grows in the Aquatic House. 

We contacted the garden and they agreed to let us have a few stalks. Medium-sized stalks were selected for their uniform age and size and they were cut just above the bottom.  We brought the stalks back to the paper lab and cut them down further using a simple kitchen knife.  We decided to use the middle portion of the stalk to ensure consistency in thickness and in length.

We peeled away the green rind using a simple, small sharp knife blade.

We tried a variety of tools to thinly slice the stalks into strips including small sharp razor blades, and various kitchen utensils such as vegetable peelers and food slicers.  We found that a simple blade was the best tool to achieve the thinnest strips.  We sliced through each stalk using the parallel cutting method.

We did encounter some difficulty in slicing the strips as thinly as we wanted, and achieving uniform thinness among all of the strips.  This may be due to our skill level in slicing, the tools available to us, or with these particular stalks of the papyrus.

The strips were soaked in water for 24 hours to swell the plant cells and fibers and allow water to fill the air spaces.  This image shows them soaking in a tray of water, weighted down under a sheet of Plexiglas and some small brass weights to ensure that the strips remained submerged.

The wet strips were removed from the water bath.  We used a standard rolling pin to forcefully press the strips flat.  At this point we observed a significant reduction in the thickness of the strips.

We returned the flattened strips to the water bath, and the process of soaking and pressing the strips was repeated several times over the course of a few days.  At this point the damp, flattened strips were lined up side by side with the long edges of each strip slightly overlapping the next.

A second layer of strips was lined up side by side, on top of and perpendicular to the first layer, forming a two-layered sheet.

For a final press using extreme pressure, this sheet was placed into a wooden book press between sheets of blotter paper and flat wooden boards.  It was left in the press for several days, switching the blotters several times, to ensure that the sheet was fully dried and completely flat.  As described in Toni’s post, this extreme pressure causes any remaining hollow spaces and air ducts to compress and the plant fibers to interlock forming a very strong physical join.

After several days, the sheet was removed from the press.  Our final product was dry and flat yet flexible, and the layers were well-joined.

Its appearance differs from that of ancient papyrus in many ways.  The white color is the most notable difference; however it is believed that the color is similar to that of an un-aged sheet of ancient papyrus.  Our sheet is also much thicker than most examples of ancient papyrus, perhaps owing to our method of slicing or pressing the strips.

Samples of ancient and modern papyrus have been examined by researchers using extremely high magnification called Scanning Electron Microscopy (SEM) and these comparisons show a difference in the overall order, regularity and size of the plant cells.  In the samples of ancient papyrus, the cells demonstrated a very regular pattern similar to chain mail, and in the samples of modern papyrus, these cells exhibit a similar order and regularity, but differ in cell size.

Both visual and microscopic differences such as these serve as a reminder that duplicating the methods and tools used by ancient Egyptians is a challenge.  Trying to make papyrus ourselves gave us a much better idea of the structure of a sheet of papyrus and how it was done in ancient times, though all of the details to papyrus-making remain a mystery.

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This post is part of a series by Conservators and Curators on papyrus and in particular the Book of the Dead of the Goldworker of Amun, Sebekmose, a 24 foot long papyrus in the Brooklyn Museum’s collection. This unique papyrus currently in 8 large sections has never been exhibited due to condition. Thanks to a generous grant from the Leon Levy Foundation, the entire papyrus is now undergoing conservation treatment. The conservation work is expected to last until fall 2011 when all 8 sections will be exhibited together for the first time in the Mummy Chamber. As each section is conserved, it will join those already on exhibition until eventually the public will see the Book of the Dead in its entirety.

It may look like fun-in-the-sun, or an excuse just to work outside, but light-bleaching is in fact, a treatment technique that is employed often by paper conservators and has been a standardized procedure used in the profession of conservation for at least 30 years.

The technique utilizes exposure to light from the sun or from an artificial light source such as fluorescent lamps to reduce discoloration in paper while it is submerged in a bath of purified and buffered water.

Conservators find light-bleaching to be useful because the process is relatively easy to control, the color of the paper appears quite natural after treatment, the paper feels stronger afterward, and the procedure avoids the introduction of another extraneous chemical into an already degraded paper.

Light from the sun is much stronger than that emitted from an artificial source.  For this reason the exposure time necessary for good results when sun-bleaching is much less than when light-bleaching indoors.  It should be noted however, that while light-bleaching improves the appearance of an object, it does not prolong the life span.

Arshile Gorky (American, born Armenia, 1904-1948). Painter and Model, 1931. Lithograph, Sheet: 11 1/4 x 9 7/8 in. (28.6 x 25.1 cm). Prints, Drawings and Photographs. Dick S. Ramsay Fund, 63.116.5.

Gorky’s Artist and Model is a 1931 crayon lithograph printed with black ink on medium weight, machine made, wove paper.  It is scheduled to go out on loan to the Philadelphia Museum of Art this October and so it came to the Paper Conservation Lab for examination.

The print was mostly in good condition except that at some point in its history, animal glue was applied to the front of the sheet just above the image.  Over time the glue had become dry and brittle, shrinking and pulling on the paper and resulting in distortion.  I carefully removed the adhesive using moisture, revealing a dark brown adhesive stain underneath.

The paper was also discolored in the image area where it was not covered by a mat.  This discoloration is the result of overexposure to light over time.  Ironically, exposure to light (using controlled aqueous baths) is what can help to reduce this discoloration.  In consultation with Eugenie Tsai, the museum’s John and Barbara Vogelstein Curator of Contemporary Art, who agreed that the stains and discoloration were distracting while viewing the image, it was decided that the print would benefit from a light-bleaching treatment.

Many precautions must be taken when light-bleaching.  Light-bleaching is an oxidizing reaction catalyzed by the light’s energy in the presence of oxygen.  This means that water is an essential component in the light-bleaching process.  During its exposure to light, the object is fully immersed in a tray of deionized water.

Also due to the oxidizing reaction that takes place, it is very important to keep the water bath alkaline (at a pH higher than 7) by the addition of calcium hydroxide both during light exposure, and afterwards by rinsing in a second alkaline bath.

Cellulose in paper generally begins to absorb UV radiation at levels below 400 nanometers, which can cause the cellulosic structure of the paper to weaken.  For this reason, a sheet of UV filtering Plexiglas is used to eliminate low level radiation by placing it over the tray of water.

This past Monday was a perfectly clear and sunny day.  I decided to take advantage of the weather and so I prepared a cart with all of the necessary supplies and rolled it outside.  I had pre-rinsed the print in an alkaline bath and carefully transported it on the cart as well.  After two hours of carefully monitored exposure during peak sunshine, from 12-2pm, the appearance of the brown adhesive stain at the top of the sheet and the overall discoloration was greatly reduced.

After rinsing the print, I allowed it to flatten while it dried by placing it between blotters under gentle, even pressure.  This process eliminated the cockling of the paper caused by the adhesive residue.

Arshile Gorky (American, born Armenia, 1904-1948). Painter and Model, 1931. Lithograph, Sheet: 11 1/4 x 9 7/8 in. (28.6 x 25.1 cm). Prints, Drawings and Photographs. Dick S. Ramsay Fund, 63.116.5.

A few more steps are necessary to complete the full treatment of this piece before it will go out on loan, including mending tears and reinforcing creases, but the light-bleaching portion of the treatment was a success.