[Histonet] cryosectioning drilling cores

[Gayle Callis]

Cheryl,

I think he is going to need to go to metallurgical/geology cutting methods.
 For one thing, the quartz and silica are NOT doing your TC knife any
favors, but mainly you cannot cut muddy water!! You could dehydrate and
infiltrate the sample with methylmethacrylate, and then cut with the TC
knife.  

I suggest you look into doing methylmethacrylate methods used for
undecalcified bone, and do LONG dehydrations on the thick cores. You may be
able to use an acetone gradient instead of alcohol, since you are NOT
maintaining tissue proteins with acetone being more efficient for water
removal in the end.    

Then embed in MMA and cut the cores with diamond embedded saws, grind them
thinner - you can grind them down to 30 um after mounting on a clear
plastic slide (glass will break during grinding/polishing).  Buehler has
all the equipment for this, and it will NOT be cheap.  Buehler Isomet saws
would cut thin 100 um slabs easily.  Most geology/metallurgical labs have
this type of equipment available. 

I am sure there are geology labs who do this kind of thing all the time, a
search?? and the methods may be published.  Paleoarcheologists deal with
similar problems, silicalized bone  or silica filled bone - they have
methods - mud may be the difference, but they also deal with muddy
specimens. I know they sometimes do their sample preps differently than
bonehead types with metallurgical resins, etc.  Give Buehler a call, they
may be able to help you too. 

Personally, I think he needs to be using geology/metallurgy expertise
rather than histotechnics - he should contact a geology dept to see what
they do or is he already in a geology dept? (oh dear!)  Want to bet oil
companies in the business of exploration and sample analysis have the
answers also. Maybe a literature search would help - gee I think I gave you
more to do than you wanted.  

Good luck on a muddy subject! 



   

At 01:46 PM 3/11/2004 -0600, you wrote:
>Hi all,
>
>I have a customer that needs to cut drilling mud cores in the cryostat.  The
>materials are extremely hard such as quartz and silica.  The problem we have
>encountered is that the section falls apart.  He does not want to use the
>tape system since when we tried packing tape and it did not hold the sample
>together.  We are using a tungsten carbide knife which is working fine and
>we section the material at 30 microns thick.
>
>I have thought about trying to infiltrate the specimen with plastic resin
>and section it on a microtome instead.  The problem is that the cores are 3
>inches in diameter and it could prove difficult getting all the water out
>out of the sample.  He is doing image analysis studies on the sample.
>
>I am hoping that some of the materials or hard sample people on the histonet
>may have some ideas to try.  Thank you for your help.
>Cheryl Rehfeld
>Meyer Instruments, Inc.
>281-579-0342
>e-mail csr <@t> meyerinst.com
>
>
>
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>
Gayle Callis
MT,HT,HTL(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology 
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367 (lab with voice mail)
406 994-4303 (FAX)