Dear Jen,
You can try to keep the samples during several hours (one night) in a dry oven ("étuve" in french") at 50 °C.  After, put the sediment in water few minutes and sieve as usual.
It worked very well with the clayed sediments that I've processed for my Ph-D.
Best


Salavert Aurélie
Anthracologue
Département de Paléontologie
Muséum de Sciences naturelles
Rue Vautier, 29
B-1000 Bruxelles
BELGIQUE
0032 2 (0) 2 627 44 83 (bureau)
0032 2 (0) 2 627 46 44 (laboratoire)

De : "CAMPBELL, Gill" <[log in to unmask]>
À : [log in to unmask]
Envoyé le : Jeu 28 juillet 2011, 9h 57min 02s
Objet : Re: Deflocculent for radiocarbon samples

Dear Jen,

We did some experiments on this and found that a series of freeze-thaw cycles worked best and did the least damage to the remains. Pop your samples in a freezer  take them out after 24 hours, and then allow to defrost.  Repeat the process twice (freeze and defrost the samples three times) and then process as usual.

We also embedded cereal grain if known date (Roman destruction deposit) in clay and floated the samples using a simple wash over technique  following soaking in various chemicals: Calgon, Sodium bi-carbonate, Sodium hexametaphosphate, Tetra sodium pyrophosphate decahydrate, and Hydrogen peroxide. We then radiocarbon dated the contaminated grain and a control sample and found that there was no significant difference in date between the 'contaminated' results and the control sample.

I'm afraid this work is not published as we are still hoping to repeat the process with more samples

Gill Campbell
English Heritage




-----Original Message-----
From: The archaeobotany mailing list [mailto:[log in to unmask]] On Behalf Of Jen Huebert
Sent: 28 July 2011 05:25
To: [log in to unmask]
Subject: Deflocculent for radiocarbon samples

Greetings,

I have a handful of sediment samples I need to process to recover charcoal for radiocarbon dating. The charcoal is embedded in a very clayey matrix. Can anyone recommend a deflocculent that will not introduce modern carbon? Preferrably one that is not too noxious (to me or to the environment).

Cheers,
Jen
--
Jennifer Huebert
PhD Candidate
Department of Anthropology
University of Auckland
Private Bag 92019
Auckland, 1142
New Zealand

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