AW: [Histonet] Cooling paraffin blocks with ice VS. Freezing Spray

[Gudrun Lang]

Cooling on ice for 10-15 min renders the block cool enough for trimming and
consecutive cutting without the need of a freezing spray.
We use cooling devices at -15 degrees. They have usually a nice
snow-surface, that gives the block  some moisture during cooling. Especially
blocks, that have to be recut, get advantage of this and are easier to cut.

I think freezing sprays render the block too cool and provide no evan
temperature throughout the block. A completly homogenously cool block is
better to cut.
I also don't like the interrupted workflow with first trimming, then putting
away and then cutting again. - but- I work with a sliding microtome and
trimming goes really fast.

Gudrun Lang


-----Ursprüngliche Nachricht-----
Von: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] Im Auftrag von Jenny Vega
Gesendet: Samstag, 29. September 2012 04:40
An: histonet <@t> lists.utsouthwestern.edu
Betreff: [Histonet] Cooling paraffin blocks with ice VS. Freezing Spray

I want to know what is your preferred method for cutting paraffin blocks in
the microtome everyday. At work I am having issues with my supervisor
because we have different ways of doing things like for example she doesn't
like to use the technique where you first trim the tissue, cool it on an ice
tray and then make a section. That is how I learned to cut in histotech
school. Instead she just trims and cuts the blocks at 4 microns one by one
using the same blade until it wears out and she cools the blocks only
freezing spray.

She doesn't like to cool the blocks on an ice tray because according to her
is a waste of time and that is why I have to use her technique but
unfortunately some blocks are extremely difficult to cut and I have to go
back to my preferred  technique. I feel I get better sections without
wrinkles when I chill and soak the blocks on ice for a couple of minutes. I
sometimes use freeze spray when the blocks get warm but when I cool them
with ice I don't need to use freeze spray that much. Her technique works but
is more successful when the blocks are well processed. I have difficulty
getting completed sections  this way and spend more time trying to get the
perfect section. Sometimes I have my good days but other times is tedious
using this technique. Another thing I notice is that the blades get worn
down quicker when you use them to trim and section. I prefer two separate
blades, one to trim and the other one to section. I feel they stay sharp for
more time.

She discourages the use of ice but then complains that we are running out of
freezing spray for the frozen sections too quickly which doesn't make sense.
It is obvious that if she encourages to use ice to cool blocks then we will
be using less freezing spray.

Another reason she discourages the use of ice is that some blocks are not
meant to be chilled which is pretty understandable. I cannot cool small
biopsies such as gastric and skin and bone because they can get too hard and
tear off from the block so I avoid that but I prefer to cool breast and
colon biopsies on ice because these are fatty tissue that can be tedious to
cut even when relying only on freezing spray.



I want to know if it's completely acceptable for me to prefer the trim, cool
on ice and section technique and if you feel is a waste of time comparing it
with other ways of cutting such as the one I mentioned.



Thanks.
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