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X-ray use on fine art wood panels

  1. Mar 20, 2012 #1
    Warm greetings from a first time poster,

    Thank you for looking. I hope I posted in the correct category and apologize if I did not. My question revolves around a late 19th century painting on wood panel made of cypress with oak strapping (2.6cm thick). I'm having the panel radiographically X-rayed to produce an image of the under drawing. I would like to know if anyone here has experience with this type of work. Specifically I would like to know what kVp and mAs settings you would use and for what duration? Any thoughts would be greatly appreciated.
     
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  3. Mar 20, 2012 #2

    lisab

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    Can you get some samples of the wood species to experiment with? I realize it won't be the original old wood, but it should be pretty close wrt how x-rays pass through it.
     
  4. Mar 20, 2012 #3

    lisab

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    Oh and welcome to PF :smile:!
     
  5. Mar 20, 2012 #4

    Tsu

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    Are you using a film/screen combination or digital radiography? The mAs includes your duration (mA x time in sec.). I typically shoot a 3cm wrist at about 72 kv and 1.5mas at a 40 inch distance using a digital system (so higher kv can be used). Cypress is usually considered a soft wood so try that technique and adjust as needed. If you are using a film/screen combo or you want more contrast to see the wood grain better, use lower kv and more mas. ie. 60kv at 3mas. Hope this helps.
     
  6. Mar 20, 2012 #5

    AlephZero

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    I can't give you any advice on the machine settings, but I know somebody who builds and restores old musical instruments (harpsichords and such like) who has an arrangement with a local vet to "borrow" their Xray machine to ckeck out the internal structure of old instruments before trying to take them apart. Consdiering a full size harpsichord is about 8 feet long by 3 feet wide, an Xray machine designed to deal with a horse or cow is about the right size for the job!

    AFAIK this is fairly routine technique in the art world now. I saw this link today: http://www.bbc.co.uk/news/entertainment-arts-17449469
     
  7. Mar 20, 2012 #6
    Thank you all so much.
    lisab, I've been told that extracting even a minute sample can lower the potential value of the work. I'm not sure it is true but it has made me cautious about sample extraction.
    Tsu, I am going to use a film/screen combo. Many thanks for your post.
    AlephZero, Thank you for the link.

    Thank you all for helping to make my first experience here a true joy. My best wishes to all.
     
  8. Mar 20, 2012 #7

    Danger

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    This will probably seem like a silly question, but wouldn't varying amounts of lead in the pigments cause inconsistent exposure across the painting?
     
  9. Mar 20, 2012 #8

    Tsu

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    Not silly at all. Yes it will cause inconsistant exposure. That's the beauty of it. Just like regular xrays where you see skin, bone, air, and even muscle shadows. I'm curious about what you are looking for or at, zeeman.
     
  10. Mar 21, 2012 #9
    Do not extract a sample from the original art work. Make a mock-up using the same woods and layer thicknesses (or as close as you can get) and just paint on a few lines using paints typical for the time.

    In any case, the damage the x-rays will do to the painting and support will be pretty minimal. It is dead, so it cannot develop cancer. And the doses needed to produce burns or notable degradation of organic substances like binders are much much higher.

    This type of work does seem to be pretty standard these days, so you should be able to find exposure values in papers describing similar work. In case of doubt, contact the corresponding author.
     
  11. Mar 21, 2012 #10
    He/she wants to see the under drawing, which is whatever preparatory sketch the artist made on the panel to guide the painting. Depending on the artist, this could be anything from very minimal to very elaborate. It can be of interest for many reasons. If an artist's under drawing technique is well known it can help authenticate a painting as by a given artist. If the attribution is not in question, this might be the first time their underdrawing technique is being explored, and would be of interest just to know how they worked. It's a hallmark of Caravaggio, for instance, that he made no under drawing at all, that he just gouged a few compositional lines into the wet primer and composed the whole painting for the first time then and there. Other interesting things would include "pentimento", where the artist veered away from the under drawing, having changed his mind once the painting got underway, or that he repainted already finished sections not being satisfied with the placement of one thing or another. The biggest surprise is finding there's a whole different painting underneath when the artist has recycled an old canvas by just painting over a previous work.
     
  12. Mar 21, 2012 #11

    Danger

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    Hmmm... it just seems to be a complication as opposed to a "beauty". It would be great for creating a "false-colour" image, but that seems a bit irrelevant since you can see the original colours without it. The only instance in which I can think of it being beneficial is if you are trying to see an old painting under a new one. If the new one contains no lead, then it would be great.
    In this case, though, the overlying paint probably does contain lead, given its age, but the sketch beneath likely has none.
    This is confusing.
     
  13. Mar 21, 2012 #12
    zoobyshoe is correct. X-ray is being used for authentication work. The painting is likely a "fully realized study" of a monumental work completed later by the artist. I've included a photo of another work by this artist in which he is preparing to tranfer the small work to a large format. The measurement lines on the side of the preparatory work are what I am looking for on my panel.
     

    Attached Files:

  14. Mar 21, 2012 #13

    Danger

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    Cool. So is this thing actually medieval, or is it a retrospective from a more modern artist?
     
  15. Mar 21, 2012 #14
    As he says in the OP, it's late 19th century painting.
     
  16. Mar 21, 2012 #15
    The drawing is Prince Vladimir the Great by Victor Vasnetsov (Russian 1848-1926) from around 1890.

    I am also curious, does anyone know what gold leaf will appear like under X-ray?

    Again I wish to state my appreciation to the forum members. Hands down Physics Forums is the BEST site on the web!
     
    Last edited by a moderator: Mar 21, 2012
  17. Mar 21, 2012 #16

    lisab

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    :smile: Tell your friends!
     
  18. Mar 21, 2012 #17

    Danger

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    I didn't express my question well, and I appreciate that you pointed it out. What I meant was whether the image is historically accurate or a romanticism of the olden days.
     
  19. Mar 22, 2012 #18
    Gold is a heavy atom that absorbs a lot of x-rays. Gold leaf, on the other hand, is very very thin. I think you are bound to see all the cracks, gaps and folds where the thickness of the gold leaf varies.

    If lead oxide was used as white, that also absorbs x-rays strongly because of the lead.
     
  20. Mar 22, 2012 #19
    Maybe these specialists can help

    courtesy Nilequeen for finding this.
     
  21. Mar 22, 2012 #20
    Vasnetsov did paint romantisized figures from both Russian folklore and history. Most of his famous work falls in the categories of social realism or art nouveau. The info on gold leaf and the link above are greatly appreciated. Thank you.
     
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