Hi Susan,

For our purpose, ultrasonic treatment does not seem to be a
good alternative, but calgon is certainly worth trying. Thank you
for your reply.

oTTo


>>> [log in to unmask] 27-1-2005 14:33:03 >>>
Hi Otto,

I have used an ultrasonic disaggregator on clay-rich palaeosols, but
don't
know if this would be too destructive to archaeobotanical samples. It
might be worth an experiment, though. For archaeobotanical samples,
I've
had good luck with hot water and sodium hexametaphosphate (=calgon) as
described by others.

Good luck,
Susan

Susan E. Allen
Department of Archaeology
675 Commonwealth Ave.
Boston University
Boston, MA 02215

tel. (617)353-3415
fax. (617)353-6800

On Thu, 27 Jan 2005, Otto Brinkkemper wrote:

> Hi Allan,
>
> Thanks for all your advises. Once, our geochemist also "dropped"
> the suggestion of Pyrophosphate, I will ask him if he can supply
> some...
>
> oTTo
>
>
> >>> [log in to unmask] 27-1-2005 10:44:53 >>>
> I am not enough of a sedimentologist to know precisely why this
might
> be
> (but will guess it depends on the precise mix of clay minerals
> present),
> but I can say that clays (sticky, stiff or otherwise intractable)
> certainly do *not* all behave in the same way and you may need to
try
> a
> variety of methods before you find the one that works for you on any
> particular occasion. Having previously told you all that sodium
> pyrophosphate was my 'disaggregant' of choice, I remembered that I
> recently had a couple of samples from Orkney in N Scotland in which
> the
> main fabric of the sediment had broken down quite quickly, but small
> 'pellets' of clay remained which would NOT come apart despite
repeated
> treatments with sodium pyrophosphate (this was a case where there
> wasn't
> time or need to be too conscientious about getting the residues
> completely clay-free, so I didn't try other methods).
>
> Allan
>
> Dr Allan Hall, English Heritage Research Fellow, Department of
> Archaeology, University of York, The King's Manor, York YO1 7EP, UK
> +44 1904 434950 (fax 433902)
>
>
> -----Original Message-----
> From: The archaeobotany mailing list
> [mailto:[log in to unmask]] On Behalf Of Wilkinson, Dave
> Sent: 27 January 2005 09:30
> To: [log in to unmask]
> Subject: Hot water for clayey samples
>
>
> Dear All
>
> I agree with Lynda Scott Cummings; I have recently had to sieve
> samples
> of VERY sticky clay which we excavated from a cave in NW England.
> Soaking samples in hot water (very approx 45 degree C) worked quite
> well, although unfortunately the clay samples contained very few
seed,
> insect or snail remains!
>
> best wishes
> Dave Wilkinson
>
>
>
> Dr David M Wilkinson,
> Biological and Earth Sciences, Liverpool John Moores University,
Byrom
> Street, Liverpool L3 3AF, UK.
>
> E mail: [log in to unmask]
> Phone: 0151 231 2245
>
> Personal Research site: http://www.staff.livjm.ac.uk/biedwilk/
>
> Interested in Archaeology, Fossil mammals or climate change?
> http://cwis.livjm.ac.uk/bes/fossilmammal/
>
>
>
> > -----Original Message-----
> > From: The archaeobotany mailing list
> > [mailto:[log in to unmask]]On Behalf Of Linda Scott
> Cummings
> > Sent: 26 January 2005 18:41
> > To: [log in to unmask]
> > Subject: Re: Hydrogen peroxide for clayey samples
> >
> >
> > Hi Group,
> >
> > Hydrogen peroxide is an oxidizer.  That means its purpose is to
> > oxidize (attack) organic remains, including the seeds and other
> > organics in your sample.
> >
> > The first thing that we use is hot water.  That disaggregates many
> > clays.  No risk to the samples, since the water is not boiling,
but
> > just hot, as you would use for washing dishes or a hot bath.
> >
> > If that does not work, we use dilute sodium hexametaphosphate to
> > disaggregate clays and find it works quite well.  Sodahex is a
base
> (a
>
> > strong base in concentration), and all bases have the possibility
of
> > attacking organics.  So far, we have observed no deterioration of
> > seeds in samples that we have treated with dilute sodium
> > hexametaphosphate.
> >
> > Linda Scott Cummings
> >
> > >Dear colleagues,
> > >
> > >One of the solutions for wet sieving of clayey samples is
> > the addition
> > >of hydrogen peroxide, which makes the clay desintegrate. I am
> > >considering using this for a set of Dutch samples, in which the
> > >preservation of the seeds is of great importance. Does anyone
know
> > >references to studies that deal with the effects of hydrogen
> peroxide
>
> > >on botanical macroremains? If possible not only concerning the
> > >present or absence of particular species in a comparison of
treated
> > >and untreated samples, but also on the corrosion observed in
> > >individual seeds? The effects could be both positive and
negative,
> as
>
> > >H2O2 facilitates sieving, which might cause less harm to the
seeds
> > >during sieving, but H2O2 may also influence the seeds by
corroding
> > >them...
> > >
> > >Many thanks in advance for your reactions,
> > >
> > >oTTo
> > >
> > >
> > >
> > >
> > >
> > >
> > >De informatie verzonden met dit e-mail bericht is uitsluitend
> bestemd
>
> > >voor de geadresseerde. Openbaarmaking, vermenigvuldiging,
> > >verspreiding en/of verstrekking aan derden is niet toegestaan.
Aan
> > >berichten via e-mail kunnen geen rechten ontleend worden. Gebruik
> van
>
> > >deze informatie door anderen dan de geadresseerde is verboden. U
> > >wordt verzocht bij onjuiste adressering de afzender direct te
> > >informeren door het bericht te retourneren.
> > >
> > >
> > >
> > >
> > >
> > >***** Rijksdienst voor het Oudheidkundig Bodemonderzoek *****
> >
> >
> > --
> > Linda Scott Cummings, Ph.D.
> > Paleo Research Institute
> > 2675 Youngfield St.
> > Golden, CO  80401
> > USA
> > (303) 277-9848
> > fax: (303) 462-2700
> > http://www.paleoresearch.com
> >
>