[Histonet] question about coating blocks with paraffin for storage

Cheryl R. Kerry tkngflght <@t> yahoo.com
Thu Nov 29 08:55:06 CST 2007

Hi Kathy--

Y'know how we do things because 'we've always done them this way'?  This is
one of those situations and it's great that you're asking 'why'.  Generally
speaking--there is no need--even though with older processing and materials
there USED to be.  If your tissues are well processed using polymer waxes,
you do not need to do this.  They won't get bugs and there should be NO
water, alcohol or hydrocarbons (xylene) left to dehydrate and shrink the

With that said--if you have underprocessed tissues like uterus, fatty
tissues or placenta that aren't completely fixed, dehydrated, cleared and
infiltrated--you may have the centers of these tissues shrink back in a
little bit.  

Having altered our procedures to save us this time every day, the best thing
I can share it to do a control test!  Leave a few days of blocks un-sealed
and check them once a week for a month or two.  It shouldn't take longer
than that now that the heat is on in your facility. If there is no
appreciable change--you're good to stop.  If you see the larger tissues
shrinking--then just seal those along the way.  If all the tissues
demonstrate some change--it's a sign they aren't completely processed and
this should be addressed at processing, not storage (and this is unlikely as
it would show on the slides.)

Hope this helps--it may not seem like a huge time savings but if every tech
takes 10 minutes a day--that is equal to almost one daily break--and who
doesn't want to keep their breaks!!!


Cheryl R. Kerry, HT(ASCP)
Full Staff Inc.
Staffing the AP Lab, one great tech at a time.
281.852.9457 office
281.883.7704 cell
800.756.3309 fax and alternate phone

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Green, Kathy
Sent: Thursday, November 29, 2007 5:21 AM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] question about coating blocks with paraffin for storage

Dear Fellow Histotechs:


We have always "dipped" out blocks after cutting them before we file
them, so I'm inquiring if any of you do not "dip" or recoat with
paraffin, have you had any problems with your blocks?  Someone said the
tissue would shrink & bugs would get into them???  Thanks for your help
in this matter.


Kathy Green, HT

Manager Histology Laboratory

Holy Spirit Hospital

503 N. 21st Street

Camp Hill, PA  17011

kgreen <@t> hsh.org

(717) 763-2930

Blackberry:  (717) 370-1726


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