Sir,

It became viscous in a weeks time. doubt it is
infected. Solution (gel would be a better term) is
very clear.No visible hyphae noted. I still have have
the solution with me. Will check it under a microscope
and also get a microbiologists opinion.
The solution  that is usually prepared in our lab
contains has a light bluish hue 1.25gm gelatin and
0.125 gm pot.chromium sulphate.I doubled the
concentration of both to see if adhesion would be
better. After  a weeks storage the bluish hue is lost
and is very clear though not transparent as it is
thick.

Is there any rationale in thinking that the adhesion
would be better if the concentration is increased?

If the subbing solution is not used cooled and is
disposed after a day why refrigerate it in the first
place? Referigerating at 2-8oC is not going to prevent
microbial growth. 

 
Sunil Thomas K


--- Barry Rittman 
wrote:
> John
> I cannot agree with you that chrome gelatin
> solutions for subbing slides
> cannot be stored in the refrigerator - at least
> overnight.  We give our
> subbed slides 3-4 coats, drying between each for a
> more uniform coating.
> We have stored the solution overnight in the
> refrigerator, allow to warm
> to room temperature and use that day. There is no
> difference between
> slides coated all in the same day and those coated
> partly on one day and
> partly on the second. I think that the reactions
> that you refer to occur
> with prolonged time and are minimal in solutions
> refrigerated overnight.
> 
> We also do not have infection with organisms and
> cannot think that this
> would be a problem with overnight storage.
> Barry
> 
> 
> "J. A. Kiernan" wrote:
> 
> > On Sat, 28 Jul 2001, Sunil Thomas K wrote:
> >
> > > I have a question regarding chrome alum-gelatin
> used
> > > for subbing. It gets very viscous when
> referigerated
> > > (difficult to pour out from the glass bottle.
> > > Is this solution warmed before slides are
> dipped?
> >
> > A smart observation, Sunil Thomas K !
> > Chrome-gelatin solutions must be used soon after
> > making. They cannot be stored in a fridge or
> > anywhere else. They cannot be diluted either.
> >
> > Try this experiment.  Make a chrome-gelatin
> solution
> > and put 1 ml of it into a test-tube or similar
> vessel.
> > Prevent evaporation with a bung, and after a few
> days
> > add 10-20 ml of warm (about 40C) water. Shake well
> and
> > observe. The gel, in which protein molecules are
> > cross-linked by Cr atoms, cannnot be dispersed or
> > dissolved in the water.
> >
> > Chrome gelatin solutions quickly become infected
> > so they should be used right away and not stored.
> >
> > ----------------------------------------
> > John A. Kiernan
> > Department of Anatomy & Cell Biology
> > The University of Western Ontario
> > London,  Canada   N6A 5C1
> >    kiernan@uwo.ca
> >    http://publish.uwo.ca/~jkiernan
> 
> 


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