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Re: orion: DSS pottery/C14

On Mon, 27 Oct 1997 17:05:15 GMT +100, GD@teol.ku.dk writes:

   [... snip ... already seen ...]

>
>And from Tom Simms:
>>    Then there was the bland notice that acid washes might work. 
>>    Horrors! The leather trappings of King Tut's horses literally
>
>You might take a look at Sheridan Bowman, _Radiocarbon Dating_, 
>1990 or one of the other references cited earlier, or either of the two 
>published scrolls lab reports in _Radiocarbon_ for information on 
>cleaning procedures which would replace your speculation with 
>information.  The basic procedure, used in labs throughout the world, 
>is hydrochloric acid, then sodium hydroxide, then hydrochloric 
>acid.  This is supplemented with other treatments and techniques, such 
>as solvents and ultrasound, according to lab judgments on what is needed 
>in light of possible contaminants.  You mentioned that acid is 
>harmful to animal skin.  While true, it is also irrelevant, since the sample 
>is going to be converted to carbon and destroyed anyway.  

   If the contaminant contains carbon, how does that remove the contaminant?
   I can see if the destruction removes the surface first and if the 
   techie is SURE the contamination does not penetrate deeply then
   the remains can be carbonized.  This procedure is likely why you have
   outliers!

   Lab people are like the rest of us.  They can slip a cog or so by times.

   BTW, you might take a look at my Seismic Subsurface Imaging Web Page
   if you think I'm some technoklutz.

     http://watnow.uwaterloo.ca/~reda/kings/kings.html

   Rather than give a series of comments about another project I'm on that
   involves C-14 dating, I'll cite this comment on a public newsgroup by
   C.E.S. Boulis, University of Pennsylvania Museum, to the following 
   question from someone wanting to know "if anyone has published calibrated
   high precision C14 dates for samples from the furniture in Tutankhamun's
   tomb?"

   His answer (which surprised me at the time):
   "Last time I checked - C14 can only be done on carbonized / burned wood.  I
   don't believe any of the wood furniture is burned hence it can't be tested.
   But there may be other carbonized material from the tomb provided that
   samples were immediately upon discovery, placed in sterile and sealed
   containers.  Same would hold true if unburned wood can be tested because
   physical handling alters C14 dates."
Continuing directly,
   "If samples were not taken back in the 1920's, then C14 testing is a waste
   of time.  The wood / carbon has been handled with bare hands (standard for
   the 1920's!), breathed upon, conserved, preserved, restored, exhibited,
   traveled the world . . ."
Also going on,
   "I know people around here who write off any carbon samples if it's been 
   sitting in sealed bags for more than a year.  In fact, I don't know anyone 
   who is interested in C14 dating anymore.  The only person I know who sent 
   samples for testing got 3 outrageous date ranges for a single deposit  - 
   none of  which were in sinc with the relative dating of the associated 
   pottery.  We suspect that that one of the field assistants - a heavy 
   smoker - may have contaminated the deposit while excavating it!"  
End of quote.

   Mr. Boulis's comment startled me at the time (31 Jul 1996), but it has the
   mark of the archaeological practitioner.  I haven't solved to MY satis-
   faction the difficulty he cites.

   His comment also tells me we may be chasing shadows unless we adopt a
   technique that has solved the problem raised.

Tom Simms

Greg 

Better get consulting.  I'll send you Boulis's e-mail address privately.