Re: Help with what I believe is a hardening issue

From: Christina Z. Anderson ^lt;[email protected]>
Date: 11/10/04-08:55:48 AM Z
Message-id: <002b01c4c735$70c26a40$6101a8c0@your6bvpxyztoq>

OHHHH, Tom, my very very bad! Thanks for clarifying.

Question, though: for our purposes of hardening gelatin, does
paraformaldehyde not work?? Could we not mix up a solution of the powder in
water at time of use and throw? Or will it not harden the gelatin?? And,
if we can mix up a solution of it that can do the job of formaldehyde, is
there a percentage you would suggest?
----- Original Message -----
From: "T. E. Andersen" <>
To: <>
Sent: Wednesday, November 10, 2004 9:43 AM
Subject: Re: Help with what I believe is a hardening issue

> Christina Z. Anderson wrote:
>> Candace,
>> I feel for you...
>> Formaldehyde is 37% solution of paraformaldehyde powder. You can get
>> it from Tri Ess Sciences in Burbank CA (800-274-6910) and mix your own
>> solution.
> This is not the case!
> Formaldehyde is a gas. Formalin is an aqueous solution of about 37%
> formaldehyde, with the addition of up to 15% methanol, and sometimes other
> additives as well.
> A pure solution of paraformaldehyde is very unstable. It will suffer
> quickly from oxidation (see Ryujis and my posting on that). After a fairly
> short time it will also start to polymerize, due to the lowered pH
> following the formation of formic acid.
> I use it for histology, and it is made fresh for each use. Depending on
> the application, it will keep from a day or two, up to a week. It is NOT
> RECOMMENDED to make the solution at home. It requires heating to 70*C,
> while adding sodium hydroxide. I can testify that the fumes from hot
> formaldehyde solution are vicious! Unless you have the proper equipment
> and skills, DON'T DO IT!
> Best regards,
> Tom Einar
Received on Wed Nov 10 08:56:48 2004

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