Detail of Book of the Dead of Sobekmose, #37.1777E, transmitted light.

One method of examination we use is the use of transmitted light, which is light which passes through a transparent material from one side to the other.  Transmitted light is very useful in understanding how a sheet of papyrus is made and therefore, how it fits back together.

Use of the microscope is another instrument which makes our work easier.  Under magnification, and in combination with transmitted light, we can see clearly what we are doing and this makes our repairs and placing of loose fragments more precise.  It’s important to make as few and as small repairs as possible in order to stabilize the piece so that as much as possible of the original papyrus is visible.

Some of the clues we look for when reattaching fragments include looking at the contour of the fragment.  It’s shape is more easily visible with transmitted light, and we can see where the edges of the fragment may fit in place.  In transmitted light one can also easily see the vertical and horizontal lines of the papyrus plant’s fiber bundles (these bring water and nutrients up to the top of stalk) which create a characteristic crisscross pattern when viewing the sheet. The orientation of these lines on a fragment tell us in which orientation the fragment should be placed—horizontal or vertical, since all fibers on one side of a roll will be in the same direction.

Pause Play Play Prev | Next

Most importantly with magnification and transmitted light we can use these lines to place fragments.  At every join, there is a “fingerprint” pattern of lines which tells us if the fragment fits there and if so, exactly where.  If all the fibers on that particular fragment do not line up perfectly, it does not fit.

To join fragments, or make repairs, we use a kozo-fibered Japanese paper which we tint with acrylics or watercolors to the color the papyrus so that the repairs are visible but blend in.

Toned Japanese paper mend

Wheat starch paste is used to adhere the mends to the papyrus.  The paper is cut into small rectangles with a scissors.  (Normally the Japanese paper is torn so that the strength of its fibers are utilized; here we do not want the Japanese paper fibers to pull on the papyrus fibers if we need to remove the mend.)  Wheat starch paste is used because it does not change the papyrus and is reversible over time.

Pasting up a piece of Japanese paper with wheat starch paste and a small brush.

After we place the mend on the papyrus, we place a blotter on top of it to dry it out and a small weight to keep it flat while drying.

See brass weight over white blotter.

As a comparison, these two photographs show how a fragment will fit in place, viewed in normal light.

Pause Play Play Prev | Next

Sometimes we see mends to the papyrus that were made in ancient times.  We’ll talk more about those cases in the next blog.

—

This post is part of a series by Conservators and Curators on papyrus and in particular theBook 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.

Detail from the Book of the Dead of the Goldworker Amun, Sobekmose. New Kingdom, Dynasty 18, ca. 1479-1400 B.C.E. Ink and pigment on papyrus. Brooklyn Museum, Charles Edwin Wilbour Fund, 37.1777E.

For several reasons, it is a rare opportunity for us to test Museum objects using this technique. One necessary condition is that the object must fit into a certain time range. C-14 dating requires that the material in question be at least 2,000 years old (and up to 50,000 years old) to get a result with a significant certainty. Fortunately, we believed our papyrus fit into this time range.

Additionally, with works of art on paper, we do not often have an expendable sample for this type of analysis. Unlike the Fourier-Transform Infrared Spectroscopy and X-ray Fluorescence Spectroscopy described in the two previous posts which require no sample and were used to investigate pigments and adhesives used on the papyrus, C-14 dating requires a sample from the object, usually about 5 mg, which is destroyed during testing. After placing as many loose fragments as best as possible (we will talk more about our repairs in a future post), we had some very small ones remaining with no ink or coloring which were unplaceable. We consulted with our curators and decided that we could use a few of these small fragments for C-14 analysis.

Fragments circled are approximately 5 mg of sample.

There are only a handful of labs in this country that do this kind of analysis. We sent our sample to the Accelerator Mass Spectrometry (AMS) laboratory in the Physics Department at the University of Arizona in Tucson for analysis. C-14 dating was developed after World War II in the 1940s and 1950s and the principal is based on the measurement of the unstable carbon isotope 14C levels in a sample as compared to modern, known standards of the stable carbon isotopes 12C and 13C, which comprise the great majority of atmospheric carbon. (Isotopes are different forms of the same element.) The 14C atoms are produced when cosmic rays bombard the Earth’s upper atmosphere and produce nuclear reactions which produce neutrons. (About 2 atoms per second per centimeter squared are produced.) These neutrons react with nitrogen atoms to form 14C atoms, an unstable form of carbon. 14C mixes up into the atmosphere and is taken in by plants during photosynthesis, and other organisms as part of the food chain.

The 14C in an organism is always being replenished from the atmosphere at a constant rate while it is alive, and the ratio between it and the stable carbon isotopes is approximately constant with time. But when a plant or organism dies, its 14C intake stops and what remains will decay at a known rate (half life of 5,730 years). Therefore by measuring the amounts of the 14C and comparing it to known 12C data, an approximate age can be determined.

Spectra of C-14 results from University of Arizona AMS laboratory.

Our results are given in the spectra above. With some interpretation this shows that the results we received from the C- 14 method of scientific analysis are indeed consistent with our current understanding of our Book of the Dead, i.e. that it was produced in the New Kingdom, Dynasty 18, c. 1420 B.C.E.

—-

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.

The two most common pigments seen on papyri are black and red.  The black ink you see most often is used for writing the letters of the hieroglyphs or hieratic text and is almost always a carbon black ink.

Fragment from the Book of the Dead of the Goldworker Amun, Sobekmose.  New Kingdom, Dynasty 18, ca. 1479-1400 B.C.E.  Ink and pigment on papyrus.  Brooklyn Museum, Charles Edwin Wilbour Fund, 37.1777E.

The ink is made by burning organic materials such as wood or oil, and then pulverizing the material before mixing it with water.  To keep the particles from clumping together, the black is mixed with a binder, probably a plant gum from the Acacia tree family.  As a valuable source of timber in Egypt, its branches may have also been used as the source for the charcoal.  As well as keeping the carbon particles suspended in the water solution, the gum binder helps to keep the ink adhered to the papyrus surface.  This ink is very stable, does not fade, and does not deteriorate the papyrus below as some metallic inks can do.

Another predominant color seen on the papyrus is red, derived from the earth pigment iron oxide.  Like most pigments used in ancient Egypt it is made from a naturally-occurring mineral, rather than an organic material derived from living sources such as plants.  The mineral iron gives it its color.  The red was often used for rubrics such as titles and headings to distinguish them from the rest of the text.  In our Book of the Dead pictured above, they denote the beginning of spells.

The ancient Egyptians used reed brushes to write the text.  These brushes looked somewhat like brushes today and allowed the scribe to vary the thickness of the line.  They were held in a wooden (or sometimes ivory) palette which had a depression to hold the red and black inks.

Scribe’s Palette with 4 Reeds in a pen holder, #37.450E, Brooklyn Museum.

Later on in the Ptolemaic period, reed pens were used.

Wooden Board with Five Scribe’s Pens attached and Bound Together with a Small Piece of Linen, #37.451E, Brooklyn Museum.

The basic palette used to paint the vignettes, or illustrations, comprised a range of pigments either mined from the earth or extracted from minerals, including blue, green, black, white, red and yellow.   It is interesting to see that the vignettes are often painted in one color within an outlined area, rather than layered to create highlights or shading.

 In addition to naturally-occurring pigments, the ancient Egyptians are credited with making the first artificially made pigment, Egyptian Blue.

Detail and photomicrograph of Egyptian blue pigment, 2.7X magnification

Egyptian blue is a glass-like pigment which was made by heating together quartz sand, copper, calcium oxide, and an alkali such as natron, which was found naturally in the waters of Egypt.  This crystalline material is then ground into a pigment and is often referred to as blue “frit”.  It was often thickly applied and coarsely ground, visible under magnification, due to the fact that it appears paler the more it is ground.  The presence of Egyptian blue in our vignettes is indicated by recent analysis with x-ray fluorescence (see future blog post for more information on analysis).

On our papyrus, we see a green called malachite, a mineral pigment composed of copper carbonate.  This green was probably also used as a source of copper for Egyptian Blue mentioned above.

Detail and photomicrograph of mineral green pigment, probably malachite, 2.7X magnification

Interestingly the blues and greens on this papyrus have darkened over time and look almost black to the naked eye, but when viewed under magnification blue and green particles are visible, indicative of what these pigments originally looked liked.

The Egyptians also created an artificial green pigment, called a green frit, very similar in ingredients and manufacture to Egyptian blue.  Other green mineral pigments have been found on ancient Egyptian materials, including copper chlorides also familiar as the bright bluish green corrosion products seen on bronze metals, as well as mixtures of Egyptian blue with yellows to create greens.

The most common yellow found on Egyptian materials is a yellow ochre which is seen in the disc above the falcon and other yellow areas.  It is colored by iron-containing minerals and contains clay and silica.

Photomicrograph of yellow and red area below falcon’s eye, 1.6X magnification

It can be difficult to identify the pigments with certainty due to several factors including the difficulty in obtaining a viable sample and also changes in the pigments over time.  A description of our analysis of the pigments will be described in upcoming blog entries.

—-

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.

In my previous post, I discussed how an adhesive introduced with an ultrasonic mister can be used to stabilize paint layers. Now you can see that close up as illustrated here of another watercolor in the exhibition, Quarry by William Thon, ca. 1952 (pictured above). Much of our work is done under a microscope which magnifies the area we are working on enabling us to be more precise and to see things not visible under normal conditions. As we work on a piece we can take photographs through the microscope known as photomicrographs which are included below. In this watercolor the artist used a range of techniques to apply his paint including a brush and a sponge, and by pouring and dripping paint onto the surface, wet on top of wet layers. Unfortunately, some of these layers are not well adhered to each other.

In the photomicrograph above you can see the top layer of brittle black paint which is lifting away from the underlying powdery yellow paint. We used the ultrasonic mister to treat this watercolor which worked very well for consolidation of the powdery yellow paint, where it would have been otherwise difficult and time-consuming to introduce an adhesive with a brush. For some of the larger paint flakes it was necessary to use the more traditional technique of inserting the gelatin adhesive to specific areas with a minute brush under magnification. See the after treatment photomicrograph below where the black paint has been set down and is no longer lifting away from the yellow layer below.

In this photograph, I am consolidating lifting and powdery paint on the watercolor, The Samuel Fleet Homestead by Frances Flora Palmer, from the 1850s. The watercolor depicts a house which once stood at the corner of Fulton and Gold streets in Brooklyn and was reproduced in an 1884 publication, History of Kings County and Brooklyn by Stiles.

The piece was previously attached to a stretcher and in the image above you can see it was darkened in the central area where it was once exposed to light. It had been treated extensively in the past, but recent examination under magnification revealed areas of lifting paint where the artist used additional gum binder to enrich shadows in the trees and foreground, and to add dimension to the horses and some of the figures.

To consolidate, or re-adhere the loose pigment particles and flakes, I applied an adhesive using this ultrasonic mister. Most of the time consolidation is done with an adhesive introduced with a very small brush under the microscope under one paint flake at a time. The advantage of the mister is that the adhesive—in this case a photo-grade gelatin in ethanol and deionized water—is formed into minute particles which are smaller than the pigment particles. Because of their size they are easily absorbed into the pigment without changing the appearance of the paint layer and can be applied to a larger area at one time. This is an incredibly successful and useful technique for stabilizing powdery paint and small, light paint flakes as with this watercolor. In this case I am carrying out the treatment on a suction table which creates a downward pull to further enhance the absorption of the consolidant into the paper.

In my next post, we’ll go under the microscope to see the before and after effects of consolidation with an ultrasonic mister on another watercolor in the exhibition.