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orion Chrisso Boulis on C14 Dating
Here is the promised update on Chrisso Boulis' interests and caveats about
carbon 14 dating. Chrisso has worked for years in the UPenn Museum
conservation department and is currently finishin up her dissertation
dealing with the Pompeii materials. She has given me permission to share
this reply (with its focus on smoke contamination) with the orion list.
(Judging from photos, de Vaux was a heavy smoker. How much did he come
into contact with the MSS? Smoking among the Bedouin discoverers is
probably to be taken for granted. Kando? Mar Samuel? Sukenik and Yadin?
Were any of the MSS team members heavy smokers? I don't recall Allegro
smoking, or Cross; probably Strugnell; Milik or Starcky? Skehan? Hunzinger
or Baillet? How about an article entitled "Inkwells and Ashtrays:
Some Modern Perspectives on Researching the Ancient DSS"?)
Robert A. Kraft, Religious Studies, University of Pennsylvania
> From email@example.com Wed Oct 29 11:36:52 1997
> Subject: Re: Carbon 14 reliability
> My opinion of C14 dating is somewhat ambiguous and probably a bit "dated."
> As an undergraduate in Classical Studies and Biology, I had courses in
> both inorganic, organic and bio chemistry. I was particularly
> interested in the
> practical applications of C14 at the time, but none of the Chemistry
> professors at that time were "impressed" with the methodology of C14.
> were also just reevaluating the so-called "stabile" rate of C14 decay.
> I should also note that the chemistry facilities my college had were good,
> but "vintage" and we had serious problems with contaminated experiments.
> We found ourselves explaining why experiments didn't work as often as we
> explained how they did work.
> When I came to Penn for graduate school in Classical Archaeology, one
> of the courses I took dealt with Aegean chronology. Dr. Iakovides spent
> some time familiaring us with C14 and its problems. (The problematic
> carbon samples came from his excavations at Gla.) We were given the
> opportunity to tour the C14 lab here at Penn (which I believe is no longer
> operational). This lab didn't come close to the standards, either
> physical or technological, which my former Chemistry professors
> said were needed for getting reliable results. It was newer than my
> college's lab, but its standards for maintaining cleanliness and orderliness
> lagged far behind. This reinforced my doubts about C14.
> On the other hand, I understand that there have been developments in
> perfecting the C14 sampling and methodology. Given that we now
> need much smaller samples, contamination could be minimalized or
> magnified for that matter. I'm not as familiar with the newer versions,
> though I've tried to find out if anyone around the museum is still
> actively using C14. So far, I've discovered that we still collect
> material in the
> field, but haven't found anyone who has actually sent it for testing.
> As for the use of castor oil. This is a plant derived oil-fat-lipid and, yes,
> it is carbon based so that by adding it to the scroll you are
> adding younger carbons to the mix. This could affect the dating, but
> it would be across the board for all pieces so treated. My gut instinct
> on this is that castor oil is a minor factor. Contamination from cigarette,
> pipe or cigar smoke would leave behind the greatest anomalies regardless
> of whether or not they stemmed from the field, the museum or archive, or
> the C14 lab. (I did notice that both the individuals at Penn's lab ages ago
> were smokers and smoked in the lab!)
> What I would want to know is whether or not the unexpected dates are
> coming from one particular lab or all? Does the group with the unexpected
> dates have something "unseen" in common? Were the samples stored
> together? Is there a pattern regarding who studied them (e.g. rampant
> smokers leaving their marks behind)?
> Bottom line, C14 dating can be usefull but we've got to be aware of the
> pluses and minuses in order to get the maximum results. Thanks for
> passing along the reference.