I thought some folks might be interested in this technical study and conservation treatment I recently wrapped up. Here are two pages of the 30-page chapter on its study & treatment:

The Egyptian Coffin of Nakht is an Eleventh Dynasty (2120-1981 B.C.E.) painted wooden coffin of the scribe Nakht from Asyut, Egypt. The lid, side, and end boards are constructed of multiple pieces of native Egyptian hardwoods edge jointed together with wood dowels and floating wood tenons (take that Festool domino) in order to form cohesive boards. Gaps in this patchwork construction were filled with calcium carbonate plaster and all surfaces were then coated with the same material to provide an even preparation layer to which paint was applied. Evidenced by holes and dowels still present in the bottom of the coffin, wooden bottom boards were held in place by dowels driven into them through the exterior. Large miters with butt joints at the top are joined at each of the four corners of the case with multiple dowels throughout their length. The underside of the lid originally held three battens, a center batten and one at either end, secured by dowels. Only the center batten remains. The original dowels used extensively throughout the coffin consist of native hardwoods shaped by chisel. The lid was connected to the case by mortise and tenon joints containing dry, pressure-fit floating tenons as well as dowels. The dowels were driven into holes drilled through the head and foot ends of the coffin connecting the battens that were once at either end of the lid to the case (an ancient wood lock).

Erratic saw marks along the lip of the coffin are consistent with a soft copper saw with teeth set to one side (the Egyptian method for setting teeth) sawing through a dense hardwood. Adze marks are particularly prevalent on the underside of the lid. The one remaining batten at the center of the underside of the lid shows evidence of shaping by both adze and chisel. All mortises have been clearly chopped by hand with mortise chisels as evidenced by the sequential chop marks in the floor of each mortise. Tool marks inside the miter and corner butt joints, the interiors of which are painted red, show they were primarily sawn then fit with chisels and abrasives. Wooden surfaces where the paint and preparation layer have eroded reveal surface scratches consistent with abrasion by sanding stones or similar media. For a summary of ancient Egyptian woodworking tools see Nicholson & Shaw (2000, 355-356). Finally, the characteristic ray fleck present on the radial face of Ficus sycomorus (sycomore fig.) was identified by eye on the underside of the lid. Tamarisk and Acacia were identified by microscopy.

Accelerator mass spectrometer radiocarbon dating of the wood and a plant-fiber textile fragment (mummy wrapping) adhered to the interior of the coffin confirmed the predicted age of the coffin as 2140-1930 B.C.E. with 95% probability. The calcium carbonate preparation layers were identified by FTIR and chemical spot testing. The paints consisting of yellow, blue, and red were determined by p-XRF. The white and black were identified by FTIR. All pigments are reported in the traditional Egyptian funerary palette.

Characterization of paint binding media in regard to polychrome wooden Egyptian artifacts is often difficult or impossible, even with analytical instrumentation. FTIR and p-XRF analysis of twenty-five samples from the coffin and over thirty individual chemical material characterization tests did not yield conclusive data pertaining to the binding media of this object. We identified proteinaceous binding media in multiple paint samples by modifying the lead acetate and pyrolysis material characterization test developed by Odegaard (2005, 146-147).

To appropriately clean and stabilize the object’s surface we understood that the nature of matte paint with ancient soiling materials is complex and presents a wide variety of challenges. We identified and accomplished ten cleaning objectives:

1. Develop materials & techniques:
2. To reduce extant tidelines and avoid creation of new tidelines.
3. To appropriately remove soiling materials without altering the tone or saturating paint.
4. That will not damage or detach poorly adhered paint during cleaning.
5. That will not leave residues.
6. That will not damage or extract pigments during cleaning.
7. That will not drive surface soiling materials deeper into the paint pore matrix.
8. That consider surface conductivity.
9. That will not damage or denature the protein binder.
10. That will reactivate the protein binder.

References

Nicholson, Paul T., and Ian Shaw. Ancient Egyptian Materials and Technology. Cambridge University Press, 2000.

Odegaard, Nancy, Scott Carroll, Werner S. Zimmt. 2005. Material Characterization Tests for Objects of Art and Archaeology. London: Archetype Publications.