Re: chrome gelatin

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From:Barry Rittman <> (by way of histonet)
To:histonet <>
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I would echo Gayle's comments re not using subbed chrome-gelatin slides
for IHC as this will interfere with some reaction and will certainly
interfere with fluorescent labels. We did however use  these slides for
routine cryostat sections of soft tissue and they were cheaper than the
alternatives. (Of course we did not include personnel costs but we were

If I might add some additional minor points.  We found that chrome-gelatin
worked best  when the solutions were made separately and then combined
just before use. Additionally we used only 0.5 gms chrome alum (per liter)
as a final concentration.
We also found it necesary to clean slides scrupulously before dipping and
give 2-3 coats of the chrome gelatin to produce an even coating over the
slide. Slides were dried in a dust free atmosphere between dippings.
Slides once completely dry were stored in the refrigerator and appeared to
keep well for several months.

Gayle Callis wrote:

> I only use chrome gelatin for decalcified bone sections IF the plus
> charge (Silane coated) slides DO NOT work.  You can make it up with
> different bloom gelatins (bloom indicating size of gelatin molecule
> 100 small, 275 and 300 large).  The reason I do not care for gelatin,
> is background staining with hematoxylin, can be reduced by dipping
> presubbed slides in NBF 10 dips, rinsing well and storing in cool
> dry box.
> 5gm gelatin in 1 liter distilled water, add 1 gm
> chromium potassium sulfate, dip clean slides in this,
> air dry and store.  Use these slides like regular, you do not
> need anything in waterbath.
> OR
> Add 10 mls of this stock to a 2 liter waterbath, like adding adhesives
> to a waterbath, dry sections in normal way - I dry bone slides flat
> at 37-40C for a couple of days, overnight is minimal.  Soft tissues
> can be dried in an oven.
> Chromium is considered very toxic, so use precautions when preparing
> the subbing solution.  I preferred the waterbath method when doing a
> large number of blocks.
> I never use subbing for soft tissues or sections for immunostaining.
> It was my backup when all else failed to keep sections on the slide.
> Gayle Calis

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