The coffin boards are wood, with some paint applied. Four thousand year-old wood. Right away, that tells us something about what kind of wood it must be, since wood generally doesn’t survive so long in the archaeological record. Because there’s been a lot of research done on Egyptian materials, we can say with some confidence that the wood is cedar of Lebanon (Cedrus libani). Cedar is a prized wood because the trees produce chemicals that make them resistant to insect damage and various forms of rot.
The first step of any treatment is careful examination. The coffin boards, despite being entombed thousands of years ago in the desert environment of Egypt and then brought to Philadelphia with its humid summers and desiccating winter heating seasons, appear to be in excellent condition for the most part; their most obvious problem being a thick coat of dust from uncovered storage for many decades. I documented the appearance of the board, noting its construction details, such as four wooden pegs and mitered edges. One curious feature was thin metal ribbons running in channels along the long axis of the board. I was unsure whether these were an original feature or something done in modern times to put the coffin back together. It seemed an unusually elaborate repair but the metal was in such good condition that I didn’t think it was 4000 years old. Even under a microscope, I couldn’t tell exactly what the metal was. There were slight traces of green corrosion, which usually means copper or copper alloy, but the metal was mostly dark grey and quite flexible, so it could be lead. I made a note to analyze it using our new portable X-ray fluorescence analyzer which has since happened and to do some research on Egyptian coffin technology. Dr. Joe Wegner, also an Associate Curator in the Egyptian Section, recommended a book about a similar coffin at the Boston Museum of Fine Arts (The Secrets of Tomb 10b) and there I found this information: “the sides have beveled edges fastened together by dowels and copper ribbons“. So it looks like those metal ribbons are original. Perhaps their unusually excellent condition has something to do with the cedar around them.
Treatment was relatively straightforward. I used a HEPA-filtered vacuum with variable speed control to remove the loose dust from the surface of the board. Conservators choose their cleaning methods based on the type of dirt to be removed and the substrate from which it is to be removed. ‘Dry’ cleaning methods (those not using liquids such as water or other solvents) are generally less likely to damage the artifact and are preferred wherever possible, although care must still be taken to ensure that only the dirt is removed and not any of the original surface. By using a very small vacuum attachment at low speed and monitoring the process closely using a magnifying visor, I was able to clean the surface safely. Not very glamorous but I’ve discovered that this artifact has a pretty important role in the history of archaeological science – see my post on the Museum’s blog for information on that!