Hi Matthew,

I would suggest a two step milling treatment :
- the first one would be a mill that is using some kind of a blade (
probably your modified cuisinart ??) to chop down the bigger
pieces to a powder in which you will probably still see fibres of up
to 1mm length
- then use a ball mill (e.g. Retsch) and give the samples another
four to eight minutes. If you find that that's not enough, you can
either do longer with the ball mill ( but with breaks, otherwise the
samples will get hot), check if you have not too much material in
the mortars or do some freeze milling. I find freezemilling with a
"real" freezer mill rather slow. However there is a trick if you have
small samples that you can shop by hand to small (2mm) pieces :
get teflon container for the ballmill, then freeze the container prior
to milling in liquid nitrogen, just before milling take the container
out of the liquid N, leaving some in the the container and put the
sampel in. The liquid N in the container should be just enough to
freeze the sample and dissappear in doing that. Then very quickly
close the containers and load them into the mill (ATTENTION :
after closing, because of the developing pressure, the containers
tend to pop open again). Then mill. This should usually do the trick,
is less intensive in liquid N and you don't need to buy an expensive
freezer mill. However, usually I find normal balmilling is sufficient.

Good luck

Oliver Brendel



On 24 Nov 99, at 23:41, Matthew E. Kirby wrote:

> Hi Isogeochemlisters:
>
> Relatively new to this venue...but, based on the questions i've read,
> i think my question is appropriate...
>
> Question:
> Any advice on how to mill tree-ring wood samples to the fine-grained
> (<250 microns) fraction suggested for cellulose extraction? Presently,
> I using a modified cuisinart with moderate success.
>
> Thanks in advance.
>
> Matthew Kirby
>
> Matthew E. Kirby
> Syracuse University
> Heroy Geology Laboratory
> Syracuse, NY 13224
> [log in to unmask]
> 315 443-3828
>


______________________________________
Oliver Brendel
Unite Ecophysiologie Forestiere
INRA - Centre de Nancy
54280 Champenoux France
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TEL 0033/383 39 40 41 FAX -39 40 69