Mystery fiber

In a recent blog post I mentioned that I am working on the painted coffin of Tawahibre, which has fibers mixed into the ground layer (gesso). In my examination prior to starting treatment, I had noted these fibers, and observed that they are present all over the coffin lid, mixed into the ground layer just below the painted surface. They are exposed in many places where there are losses-here is an image of one area where the surface of the coffin is badly damaged, revealing these fibers:

Fibers visible in the ground layer of the painted coffin lid

There are quite a lot of these fibers in some areas (as seen in the photo above), and then in others, there are very few. They are found in areas where the ground is thick and also where it is applied very thinly. They are not arranged in any particular way-they appear to have been mixed haphazardly into the ground. The fibers are light brown in color, and while most of them are very stiff, they react almost immediately to moisture, becoming very flexible when wet. I had initially assumed that these were plant fibers-possibly flax-but they always seemed a bit odd, and to be honest, these fibers remind me a little bit of sinew (animal tendon).

As I have been working on the coffin, several of these fibers “presented themselves to me” for sampling-meaning, as I’ve been working to stabilize some of the areas with these fibers, a couple became detached, allowing me to investigate them further using PLM. So far I have looked at 2 samples, and both look the same. I prepared the fibers by mounting each one on a glass slide with water. When looking at them in plane-polarized light, they look like this:

Two different fibers from the coffin ground layer viewed at 50X magnification

I didn’t really know what I was seeing-it was difficult to pick out any really distinguishable features, so I then viewed both fibers under crossed polars. This is what I saw:

Same two fibers viewed under crossed polars at 50X magnification

What the heck is that? I’ve never seen anything like this before. When I showed this to a few other people, the first reaction has been-it looks like a worm! And it totally does. This very regular banding pattern has got to be characteristic of something-I just don’t know what.

I thought I had a lead last week-I found this image in a book, showing a bundle of sisal fibers with a commonly-seen spiral element:

Sisal sample showing a characteristic spiral element. Image from “Color Atlas and Manual of Microscopy for Criminalists, Chemists, and Conservators” by Nicholas Petraco and Thomas Kubic, p. 94.

However, just last week I obtained a sisal sample from one of the Winterthur art conservation graduate students and I’m pretty sure that’s not what I have. The sisal sample looks distinctly different to me-here it is in both plane polarized light and under crossed polars:

Sisal reference viewed at 400X magnification in plane polarized light (left) and crossed polars (right). Also, note the difference in magnification between these fibers, viewed at 400X, as opposed to the coffin mystery fibers above, viewed at 50X.

For the moment, I’m stumped. But I’m continuing to investigate this and to get input from colleagues, and I’m open to suggestions/ideas! I’ll also certainly provide more information when I know more. To be continued…

 

  • Pingback: Mystery fiber update | In the Artifact Lab

  • http://www.lucienvanvalen.nl/ lucien

    One question on your pictures: your fibers are 500μm and the others you compare to are only 50μm?

    • mollygleeson

      hi Lucien-good question! Yes, the “mystery fibers” are much larger than the fibers I am comparing them with in this post (sisal). This is why the scales on the images are different-the images of the mystery fiber were taken at 50X magnification, and the images of the sisal reference were taken at 400X magnification (if I had posted the images of sisal taken at 50X magnification, they would look much smaller and it would be difficult to see much of anything!). This is another indication that the mystery fiber is not sisal. Thanks for asking!

    • http://twitter.com/pennartifactlab pennartifactlab

      hi Lucien-good question! Yes, the “mystery fibers” are much larger than
      the fibers I am comparing them with in this post (sisal). This is why
      the scales on the images are different-the images of the mystery fiber
      were taken at 50X magnification, and the images of the sisal reference
      were taken at 400X magnification (if I had posted the images of sisal
      taken at 50X magnification, they would look much smaller and it would be
      difficult to see much of anything!). This is another indication that
      the mystery fiber is not sisal. Thanks for asking!

  • http://www.facebook.com/nesrin.elhadidi Nesrin El Hadidi

    I never heard that sisal was used in ancient Egypt. You have to check and compare with native Egyptian plants.

    • http://twitter.com/pennartifactlab pennartifactlab

      I also have found no references to the use of sisal in ancient Egypt! Now that I don’t think that’s what it is, I am looking into other possibilities. I strongly suspect that this is an animal, rather than plant, based fiber.