[Histonet] question about coating blocks with paraffin for storage

Rittman, Barry R Barry.R.Rittman <@t> uth.tmc.edu
Thu Nov 29 06:24:10 CST 2007

this is one of those it depends answers.
Sealing the surface is essential, not only for blocks but for mounted section that are kept in reserve.
A quick dip in paraffin wax while it will temporarily seal the surface doe not mean that the paraffin has fused with the block, it may have merely coated the surface. This can separate at a later stage especially with long term storage, temperature changes etc.
It is, in my experience, preferable to run a hot blade over the surface to ensure that the surface is in fact sealed from the atmosphere.
We have only had problems when storing tissue blocks for long periods of time when we have used the dipping method.
Disadvantage of the hot blade is that it takes a little more time and you do lose a very small layer of tissue. However if you are going to recut some time in the future you will almost certainly lose some tissue anyway.
Hope that this helps.


From: histonet-bounces <@t> lists.utsouthwestern.edu on behalf of Green, Kathy
Sent: Thu 11/29/2007 5:20 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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