Unsworded by Find-Conservators

Yesterday by train to Gothenburg with the Djurhamn sword sitting in its package on the hat rack above my head. I spent much of the trip in the pleasant company of the Realm’s Herald, numismatist Dr Henrik Klackenberg, who happened to be on his way to a church excavation near Skara where he was going to classify newfound coins.

In sunny Gothenburg I caught a ride with a soft-spoken Kurdish taxi driver to Gamlestaden, the site of a 15/16th century predecessor of Gothenburg, currently an industrial suburb, where Studio Västsvensk Konservering resides in a refurnished textile plant. Here I was received by friendly conservators and showed around.

I love visiting conservators’ studios. They always have these really wild new finds that nobody’s heard of yet. Often even their excavators don’t know what they’ve found, as a lot of metalwork is lifted in soil blocks. Nor was I disappointed this time.

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Inger Nyström and Annika Carlsson unpacked the sword and put it into the SVK’s X-ray room. It’s a giant camera: you put X-ray photographic film on the floor, rest your find on it, and then shoot X-rays at it from an emittor hanging from a ceiling-mounted winch. This way they can photograph objects several metres long. The shots (developed in a real analog photo lab with a red lamp and smelling of vinegar!) showed that the sword is very well preserved and made entirely out of iron and steel: no incrustations of more precious metals. Its immediate future will entail prolonged leeching leaching in destilled water, removal of rust bubbles and impregnation with wax. Then back to Stockholm and a prominently located display case.

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While the X-raying took place, Annika and Ebba Phillips took me down to the ground floor and showed me their freeze dryer, a large submarine-like contraption currently containing bits of the Göta wreck, an early 17th century vessel.

The ladies explained to me how freeze-drying works as a conservation technique for waterlogged wood. First you replace as much of the water in the wood as you can with PEG, polyethylene glycol. If you just leave the wood to dry at this stage, the microscopic capillaries in the wood will collapse, your object will shrink and warp and it will be a mess. With freeze-drying, what you do is you freeze the whole thing so the capillaries are rigid, and then you apply a negative gas pressure so the water left in the wood wanders out and condenses elsewhere. The capillaries, instead of being filled with water and PEG or empty and collapsed, are still wide open and filled with air, their interior walls plastered with PEG.

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Beside the freeze dryer was Ebba’s new baby, an exceptionally mind-blowing — and large — find: the Brissund cannon. It sank in 1566 off Gotland with a ship of the Danish-Luebeckian fleet, was found in the 1980s and broke the surface less than three weeks ago. It’s a complete iron cannon still in its wooden carriage, made with the same technique as a wooden barrel: eleven long iron staves welded together to form a cylinder and encircled along its length by a large number of iron hoops. Ebba showed me a large piece of rusty crust that had fallen off the muzzle-end, containing well-preserved rope that had wrapped the barrel between the hoops. Magic stuff! And insanely complicated to conserve, what with the combination of huge chunks of incompatible materials. Ebba’s going to spend years on it.

I also had a peek at finds from a Swedish Catalina airplane shot down over the Baltic by the Russians in 1952, incredible Migration Period metalwork from the Finnestorp war booty sacrifice, a High Medieval buckler shield found off Skanör and sundry other goodies. My colleague Robert Hernek showed up with a Roman Period urn burial in a soil block, fresh from his dig. Then I said goodbye, had a late Thai lunch, located a bunch of geocaches and went home to Stockholm.

Update 10 October: I have no idea why my handheld computer put the wrong time stamp on those pics.

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Comments

  1. #1 mugabe
    October 9, 2007

    Cool. Quite the hybrid of a ‘CSI’ forensic lab and Q’s test center in the Bond movies.

  2. #2 blf
    October 9, 2007

    How long is the conservation process for the sword? I realise it’s very early days, and there presumably will be unexpected problems, but what’s the current (presumably rough) guess?

    On PEG, isn’t there some sort of an issue with using it? What I’m trying to recall (unsuccessfully) is both(?) the Vasa and Mary Rose are having problems due to, as I (very!) vaguely recall, the use of PEG; something about sulfuric acid. Wikipedia‘s article on the Vasa mentions a problem with sulfuric acid, but does not link that to the use of PEG, so perhaps (probably!) I’m just confused here… and it’s late at night, I should go to bed…

  3. #3 Martin R
    October 10, 2007

    Mugabe, yeah, Inger is very Q, and Annika & Ebba are typical Russian spy babes. Anybody should be able to see that they’ve received special education in Irkutsk and then been planted at the SVK.

    Blf, I actually forgot to ask about the time estimate, but I believe two or three months would be realistic. It’s mainly a question of waiting until the clorine ion concentration in the leeching water drops.

    As for sulfur in the Mary Rose and Vasa, I believe that’s a byproduct of decaying original iron bolts and not the PEG’s fault.

  4. #4 Thinker
    October 10, 2007

    Following this as it progresses is a lot of fun! Will you or “Q and the Spybabes” (which incidentally would be a good name if they were to set up a band) be able to give us interim reports?

    [nitpick]
    I assume the sword is treated by leaching to remove the chlorine ions, although it would be cool if leeches such as Hirudo medicinalis could also be put to work in conservation of old objects, now that they are slightly less in fashion in the medical profession…
    [/nitpick]

  5. #5 Martin R
    October 10, 2007

    I’ll keep you guys posted on developments around the sword. Yesterday I wrote to four museums saying basically “I’ve got this sword that I know you all would like to exhibit. Who can give me the best exposure?”.

    Thanks about the leaching! Silly mistake.

  6. #6 Tobias
    October 10, 2007

    During its many years on the sea floor, substantial amounts of sulphur was deposited in The Vasa’s construction. This sulphur is now oxidizing and forming sulphuric acid, a process being accelerated by the present iron bolts. This acid, in turn, slowly dissolves the cellulose in the wood, which is not beneficial to the structural integrity of the ship… As regards PEG, i read somewhere that it is lowly being broken down, again due to the presence of iron.

  7. #7 Thinker
    October 10, 2007

    I didn’t realize the finder of an object actually has any say in where it gets exhibited. I would have thought the antique object simply becomes the property of the state, and then the authorities decide where to display it, if at all. How is this done?

  8. #8 Martin R
    October 10, 2007

    No, you’re right! It’s just that the process where the authorities decide which museum gets a find is pretty slow, often taking years. In the mean time, I decide on temporary storage. And what storage could be better than a climatised display case in the entry hall of a major museum?

  9. #9 Lars L
    October 10, 2007

    Any particular museum in mind? Tekniska Musseet, perhaps? I know they deal a bit with history! Skansen could be a second choice..

  10. #10 Martin R
    October 10, 2007

    I’m going to fight to the death to make sure that sword ends up in the Postal Museum or the Tobacco Museum.

  11. #11 Maria R
    October 10, 2007

    I’m starting to think you are a time-traveler. “Yesterdays” date isn’t the same as on the pictures. The camera never lies, or?!

  12. #12 Martin R
    October 10, 2007

    Damn, I have no idea why my handheld computer time-stamped those pix two years into the past.

  13. #13 Tegumai Bopsulai, FCD
    October 10, 2007

    the Djurhamn sword sitting in its package on the hat rack above my head.

    Shades of Democles!

  14. #14 Tegumai Bopsulai, FCD
    October 10, 2007


    Update 10 October: I have no idea why my handheld computer put the wrong time stamp on those pics.

    My guess is the clock reset itself the lat time you let the batteries run down.

  15. #15 Martin R
    October 10, 2007

    I thought so too, but I haven’t corrected the date lately and it’s currently correct.

  16. #16 blf
    October 10, 2007

    The issue with PEG which I trying to recall may be one (or both?) of two things. In no particular order…

    First, there’s a hint PEG may be involved in the formation of formic acid (not sulfuric acid):

    http://www.xolopo.de/agrarwissenschaften/formic_acetic_acids_archaeological_wood_a_comparison_15750.html
    http://www3.interscience.wiley.com/cgi-bin/abstract/112598881/ABSTRACT?CRETRY=1&SRETRY=0

    The content of formic acid is related to the intensity of conservation and, hence, the PEG content in wood. Accordingly, formic acid found in the hull of the ships may partly be a result of PEG degradation.

    Second, and this is perhaps what Tobias was alluding to, the PEG and iron bolts apparently react:

    http://query.nytimes.com/gst/fullpage.html?res=9D02E6DB1439F937A25756C0A9649C8B63&sec=&spon=&pagewanted=all

    “The polyethylene glycol makes iron bolts rot, and the iron makes the PEG decompose … They’re very bad for each other.”

    https://dspace.ucalgary.ca/bitstream/1880/44980/1/Jalilehvand_2001_J0006.pdf

    It is now known that metallic iron rapidly corrodes in contact with PEG [14], indicating that there is a specific metal surface-PEG interaction and/or complex formation between PEG and iron ions.

    Reference [14] is given as Guilminot, E.; Dalard, F.; Degrigny, C. Eur. Fed. Corros. Publ. 2000, 28, 300-309, which I have not attempted to track down.

    (I suppose these “two things” might be the same thing? They both involve the PEG degrading (reacting?). However, all this is all outside my area of expertise!)

  17. #17 Claes
    October 11, 2007

    Next time you visit Göteborg you must come and visit us at Arkeologikonsult´s office in Klippan, near the medieval castel of Älvsborg.

    Claes

  18. #18 Martin R
    October 11, 2007

    Thanks Claes, maybe you can get me a speaking gig?

  19. #19 Sávon
    November 15, 2007

    I read about Artemisia Gentileschi this morning, and looked at pictures of her painting in a book. I saw your sword in a painting “Judith with her maidservant” c 1618. In Italy.

    But after a closer look I saw that your swords “handprotection” is turned down instead of up as in her picture. Are they made so when it was new, or has it been done afterwards for some reason?
    Artemisias sword can also be seen here. http://www.artemisia-gentileschi.com/judith3.html
    But the picture in the book is more detailed.

  20. #20 Martin R
    November 15, 2007

    I see what you mean!