Wood ID

I’m currently treating 7 fragments of a painted wooden coffin from Abydos. Lately, many of our visitors have been asking what kind of wood was used to make this coffin. This has actually been a question that we have been asking ourselves, and we are trying to see if we can come up with an answer.

In ancient Egypt, large timbers for coffin-making were scarce, so the wood was either imported from places like the Mediterranean, the Near East, or from other parts of Africa, or the Egyptians would cobble together smaller pieces of wood from local sources. Based on previous studies, we have a finite list of types of wood that are known to have been used, but from there we need to move to looking at the object itself.

These images show the exposed wood on the side (left) and back (right) of one of the coffin fragments. Can you guess what type of wood this might be?

These images show the exposed wood on the side (left) and back (right) of one of the coffin boards. Can you guess what type of wood this might be?

As conservators, we are educated not only in object treatment, but in the analysis of objects, and the examination of tiny fragments of objects, like plant and textile fibers, wood, and pigments. But many of us don’t do wood ID all that often, so it can take awhile to get set up, to re-orient ourselves to what we’re seeing in the samples, etc. AND it requires a sample, which we don’t often have access to. Fortunately, for me, I have some already detached samples from these boards and access to someone who does this type of work more frequently, archaeobotanist Dr. Naomi Miller, so I turned to her to help me with this work.

Dr. Miller looked at the samples I had and selected one that looked promising, due to the exposed cross-section on one end. I mounted this sample under our binocular microscope and took a photo, to help her study it further and compare to known reference samples.

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The wood fragment with exposed cross section, 60X magnification

From this sample, Dr. Miller was able to determine that this is a hardwood, based on the presence of clearly visible rays and thick-walled pores, many of which are radially paired (pointed out below).

Slide4Based on these features and the known types of hardwoods used in ancient Egypt, this helped narrow down the likely possibilities to Common ash (Fraxinus excelsior L.), Carob (Ceratonia siliqua L.) and Acacia (Acacia sp.). Dr. Miller considered other types but ultimately excluded willow (Salix), oak (Quercus), elm (Ulmus) and sycamore fig (Ficus sycomorus) due to either the presence or absence of certain features.

In an attempt to further narrow down the possibilities, I cut thin sections from the sample that Dr. Miller examined, from the cross-section and tangential surfaces, and wet-mounted them on glass slides. Looking at these thin sections with our polarizing light microscope (PLM), I was able to see some of these features a bit more clearly.

Cross-section, 50X magnification

Cross-section, 50X magnification

In the cross-section above, the pores are visible as solitary or paired, and mostly uniseriate (1-cell wide) rays are visible. The tangential section also shows mostly uniseriate rays, but some bi-seriate rays are visible as well.

Tangential section, 50X magnification

Tangential section, 50X magnification

Cutting these sections from the wood sample, which was quite degraded, was difficult and unfortunately I’m not really able to pick out many other features from the sections that I examined. I will have to get Dr. Miller to weigh in on this again, but in the meantime, I’m going to go out on a limb and say that I’m leaning toward this wood being acacia. One thing I forgot to mention is that the wood of the coffin board fragments is a deep red-brown color. Acacia is known for being a red, hard, and durable wood, and while it produces small timbers, we know that it was used for coffin-making, among other things.

Treating fragments of a Middle Kingdom painted wooden coffin

If you’ve visited the lab in the last few weeks you may have seen me, head bent at the binocular microscope, working away on fragments of a painted wooden coffin from Abydos. These fragments (7 in total) were excavated in 1901 and have been here at the museum ever since. As I described in a previous post, these boards were severely damaged by termites prior to excavation, and the painted surface, while very well-preserved in some areas, was cracked, flaking, and barely attached in places, not to mention covered with grime.

One of the coffin fragments, which features a portion of a frieze of objects that includes two vessels with spouts and a bolt of clothing.

A before treatment photograph of one of the coffin fragments, which features a portion of a frieze of objects that includes two vessels with spouts and a bolt of clothing.

On the board in the image above, the paint was actually in decent condition. After cleaning the surface with bits of a kneaded rubber eraser, I stabilized the edges around the paint losses with a 2% solution of methyl cellulose in water. With the help of an intern, we sorted through a box of much smaller fragments that presumably had become detached from the 7 larger boards at some point, and we found two small fragments of wood with painted decoration which belonged to this board. These fragments were adhered in place with a 1:1 mixture of 5% methyl cellulose and Jade 403, an ethylene vinyl acetate emulsion.

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In this image the red arrows point out the two fragments which were adhered in place after cleaning and consolidation.

Here is a view of that area from the back after mending those fragments:

e12505e_backbeforemendingThe termite damage is evident from the back, and as you can see, the wood is very thin in this area in particular, only about 1mm thick along the join edges between the small fragments and the larger board. The small loss to the right of the upper fragment is an area where the wood and painted surface have been lost completely.

Because the wood is so thin and fragile, I decided to provide some support to this area, by first adhering a piece of Japanese tissue paper over the loss from the back with a 5% solution of methyl cellulose.

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A detail of the Japanese tissue paper support adhered over the loss

I then filled the loss and the small gaps along the join edges of that upper fragment from the front, using a fill mixture made from 5% methyl cellulose, glass microballoons, and powdered pigment.

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A detail shot showing the fill from the front

Here is an overall view of the board, after treatment:

E12505Edt02_blogThe fill mixture I used worked nicely, and I’m now using it to stabilize the edges of some of the lifting paint on the other coffin board fragments where the painted surface is in worse condition. I will post photos soon showing what the coffin boards look like before and after treatment.