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

joelle weaver joelleweaver <@t> hotmail.com
Sat Sep 29 18:11:53 CDT 2012

JennyYou don't need to respond to this, but I will post in case there is anyone else out there who is going through the same experiences and feeling discouraged.  There are many people in the field like this. I have been out there at least a little while and I went through the same response once out of histology school and get attitude all the time, still to this day, even though I have jumped through all the usual "hoops" at this point. I can tell you that while  working in some labs, I thought of quitting histology almost weekly because I got so sick of this kind of thing  People have gotten into the field in various ways,  and they sometimes get into ruts and they don't get out there much to learn all the new techniques and information. People coming in with ideas threaten the "status quo",  and sometimes it is just difficult many people to change.  I haven't quit histology yet though,   and you shouldn't  let other people drive you out or make you doubt yourself either. Trust me, we need educated and trained people in this field in a desperate way. Look, we all have stuff to learn,  new and old! If you stop learning and believe you "know it all",  you are a real drag to everyone and holding back others who want to learn and grow. If you are a newer tech, I think that can be a plus. You are fresh and full of enthusiasm and new ideas. The "seasoned" can share what they have learned from time and experience, and you can bring new ideas and your fresh enthusiasm and energy- I don't see why that can't be a "win-win". Anyhow, all of this are just my opinions, and I may get slammed for these comments like I have many times before,  but as far as I can tell  from what you have posted,  you are not "wrong", and your techniques seem reasonable for the hospital clinical setting. In addition, you seem to understand why they work  for you and the technical rationale behind them. To me this is good. Many people have been taught how to do things, but not why.  We need more people who want to know why and who care about quality. Please read the other posts about blades ( they said it best already) but I feel that is crap about skimping  on them ( sorry) . No patient is worth less than any disposable blade. That is why they call them disposable. You should not waste supplies, that is irresponsible, but within reason you need decent supplies to get the best quality you can possible can. Ice is cheap, much cheaper than freeze it spray..(as someone mentioned and a good point) .. so there is no valid economic/operational reason there that I can see to justify any of that. 

Joelle Weaver MAOM, HTL (ASCP) QIHC
 Date: Sat, 29 Sep 2012 18:26:38 -0400
Subject: Re: [Histonet] Cooling paraffin blocks with ice VS. Freezing Spray
From: histotech411 <@t> gmail.com
To: joelleweaver <@t> hotmail.com; histonet <@t> lists.utsouthwestern.edu

Thanks everybody for your answers. I cant respond them all but I concluded that the best way to get good sections is too chill the blocks on ice because I agree that it facilitates the process. 

I really don't understand why my supervisor depends so much on freezing sprays to cut and the pathologist has never complained about artifacts caused by them but I do believe that they are present because I have seen them getting formed. It makes sectioning difficult because you try to get sections free of holes and that contributes to the problem. 

At my lab is the same thing. My supervisor is in charge of the embedding and she just use the ice only for hardening the paraffin block. We don't have a standard embedding center with cold plate. Since is a small lab we just have a heating plate where we handle the specimens and place them in the molds and we cool them on ice trays. After they are removed from the molds they are placed on the counter in numerical order and they reach room temperature and get warm. I do think that if they get cold and moistened since the beginning it can facilitate the sectioning process except for certain tissues that are not well processed. In my lab I change the reagents in the tissue processor weekly but they get dirty too quickly because we processes a lot of breast and colon tissue so is hard to get perfectly processed tissue daily. We are under a tight budget and we can't waste materials too quickly. 

This situation with my supervisor has caused me a lot of frustration. I have noticed that every tech has their own method to do things but unfortunately there are people who are not receptive to new ideas and they immediately criticize and say you are wrong specially if you are young and you have recently started your career. I have though on several occasions  that all I learned in histotech school have been worthless because everybody in the lab does things differently and this has made me question my ability of being a good tech because I have experienced difficulty using their microtomy technique but I have realized that I am not wrong. 

Another issue was the use of microtome blades. Since I started my supervisor has told me to use the minimum amount of blades as possible because we are under a tight budget but I have noticed that some of those blades are of poor quality and since we cut a lot of tissues that are hard, calcified or have sutures they wear the blades too quickly. It's hard to cut many blocks using  only one blade that you use to trim and section. I have realized that I am successful obtaining good sections when I chill the blocks on ice for a couple of minutes and change the blade immediately after encountering difficulties with a block. It's not worth to sacrifice the quality of the samples just to be cheap and save some money.

My supervisor is a great person and tech with a lot of experience but she is not very open to new ideas. Her demands to save money can be unrealistic when the correct technique is not being used . With her technique of course you are going to waste excess of freezing spray and blades but she doesn't understand this. Perhaps I need a change of environment which is unfortunate but is difficult to work like this.

Thanks everyone for their input

On Sat, Sep 29, 2012 at 8:56 AM, joelle weaver <joelleweaver <@t> hotmail.com> wrote:

My experience and training is to use some method involving ice or at the very least a cold-retaining tray made to chill blocks. I also was taught this method in histology school , in clinical training at four quite large institutions,  and also have used some variation of an ice cooling method in every instance in my career working in clinical and research settings. There are always variations in technique from lab to lab, but freezing spray has been generally discouraged  for constant use at the microtome, since it can introduce artifact in sections if over used. ( It is pretty easy to see the effect on the face of the paraffin block, and that is not even under the microscope.) I actually almost never use freezing spray personally for regular paraffin microtomy. I  do use it when doing frozen sections on occasion, but then it is typically only for difficult specimens such as fatty breast or soft/fattty lymph nodes that need very cold temperatures. I sometimes use it to cool only the backside of paraffin blocks during embedding when I am being impatient, and I avoid spraying directly on the face, and that is about the extent it of freeze spray's uses for me. 

Personally, I prefer my blocks quite cold, in fact, one thing I don't like where I currently work , is that blocks are allowed to get to room temperature after removal from the embedding cold plate. I feel that I can more efficiently get good sections when the cold temperature is maintained and uniform though the block,  rather than re-cooling a warmed  room temp. block.  Overall,  I would expect constant and direct application of the freezing spray would be more of a problem than anything involving ice,  which would "flash freeze" mostly the surface,  and not cool throughout, which is why you have to keep spraying it.  Of course, I am not talking about leaving the faced block surface on the ice for so long a time that it becomes "water-logged"- but if you are sitting at your microtome and cutting diligently, and not leaving faced pecimens just sit there, I'm not sure how this would be an issue. 

In general I think the combination of ice and water benefits most specimens  ( especially GI and Liver cores, bloody stuff,  and other types-that can sometimes be brittle and delicate due to processing)-I feel that the small amount of moisture that transfers from contact with the ice aids the smoothness/ reduces brittleness of the section, reducing "shatter" artifact. I feel that I would be unable to get sections without chatter in hard/dense tissues such as uterus body, cervix, bloody specimens and others without using ice. The only exception for me, might be brain which can cut better warm.

 I am sure you must be frustrated, but if this is the clear direction of your supervisor, and they are not receptive to making any changes or allowing you to use your preferred technique, and not interested in new different methods,  then  I am not sure that there would be much that you can do other than comply with their policies. I know it is hard when people are not open to new ideas and techniques . I  had have that experience and  those feelings  quite often over the years, but just try to stay postive, do the best you can. 


Joelle Weaver MAOM, HTL (ASCP) QIHC
> Date: Fri, 28 Sep 2012 22:39:31 -0400
> From: histotech411 <@t> gmail.com

> To: histonet <@t> lists.utsouthwestern.edu
> Subject: [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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