[Histonet] Molds- cold vs warm
nmargaryan88 at gmail.com
Fri Sep 9 20:13:47 CDT 2022
Thank You so much Jay, for such detailed explanation and for permission to
use your email to address.
My sincere regards,
On Fri, Sep 9, 2022 at 5:00 PM Cooper, Brian <bcooper at chla.usc.edu> wrote:
> Thanks for saying this Jay!! I have to say, it's been a while since we've
> had such a great response on Histonet!! Everything you said is spot on.
> Happy Friday everyone!
> Brian Cooper
> Histology Supervisor
> Children's Hospital Los Angeles
> Sent from my mobile
> On Sep 9, 2022 2:37 PM, Jay Lundgren via Histonet <
> histonet at lists.utsouthwestern.edu> wrote:
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> Whoever is telling you to use cold molds needs to go back to clown college.
> That is totally, 100%, absolutely, wrong.
> There is some debate as to embed "wet" (cassettes submerged in paraffin
> bath) or "dry", and I will accept either, as mostly a matter of personal
> preference. BUT, in both of these cases, the molds are hot.
> I have been a Histotech for five decades, trained at Armed Forces Institute
> of Pathology (back when that used to mean something) and I have NEVER seen
> anyone using cold molds.
> It is a guaranteed way to get cold fractures and cracks in your blocks, or
> to pop tissue out when you are cutting, which might be irretrievable. Just
> think how much time all those re-embedded blocks are going to save you!
> Also, you won't be able to easily re-position specimens in the block, to
> put them "on edge" or "on end", for example. The tissue will instantly
> stick to the cold mold. And if you want to re-position it, guess what,
> you'll have to warm the mold up to get the tissue unstuck. How's that
> (non-existent anyway) time savings now?
> If you want to prove to whatever jackass suggested this that they are
> wrong, get a big stack of every histopathology textbook you can find.
> There is nothing in any of them talking about paraffin embedding with cold
> As a matter of fact, every single textbook will specify molds at the same
> temp as paraffin.
> Anyway, it doesn't even make sense, thermodynamically. Heat travels from
> hot to cold. Those "cold" molds will be the same temperature as the
> paraffin, almost instantly. Did it take a tiny amount of heat out of the
> hot paraffin? Yes, but not enough to noticeably cool the blocks faster. The
> amount of heat from the paraffin used to warm the mold is trivial compared
> to the total heat of the system. That's why cold plates have huge, noisy
> refrigeration units. You can't argue with thermodynamics.
> If you are having trouble getting your blocks to release, use mold
> release! Viola!
> I used to think it was
> superfluous, but now I consider it compulsory. This is probably the answer
> to most of your issues.
> I don't know who is suggesting using cold molds, but I can pretty much
> guarantee that it's a pathologist who thinks his slides are taking too
> long, and knows nothing about histopathology, or a lab manager, who knows
> nothing about histopathology. This next part is directly to them.
> To Whoever Suggested Cold Molds: The answer to getting your slides out
> quicker is buying more equipment and hiring more techs, and holding
> everyone to standards (30 blocks/hr cutting, 60 blocks/hr embedding).
> Making nonsensical, uninformed suggestions only exposes your ignorance.
> Please feel free to show them this reply.
> Jay A. Lundgren, M.S., HTL (ASCP)
> Histonet mailing list
> Histonet at lists.utsouthwestern.edu
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