Re: Gelatin/Chrome Alum for bone

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From:Mary Stevens <>,
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Hi Gayle,

Thanks for the suggestions.  I never thought to post dip in formalin.  It sounds like a possible solution, my only concern is that the coated slides are used for undecalcified, MMA bone - most are long bones from large animals - so maybe even alittle bit of cross linking will be too much - but it's definitely worth a try.  A couple of years ago, someone mistakenly used the Bloom 100 - for coating, and we lost a lot of sections.  We've tried Silinizing - and just about every other slide adhesive out there (including plus slides) - some were better than others, but nothing worked for everything like the gelatin/chrome slides.  We do tip the slides, but I've never had to bake them at 37C - we can try that as well.  Do you let the slides dry before placing them in the oven?  Why flat?  We do hundreds of these at a time, and keeping them in the dipping racks would be our only possibility - wish we had a huge pizza oven in the lab!!

Have a great day -

>>> Gayle Callis <> 07/06 5:33 PM >>>
Some things to try here:

1.  Make sure you drain your slides tilted steeply towards the label for
air drying,       this helps prevent the gelatin from concentrating on an
area of the slide near a       section.
2.  After coating the slides, dip them in NBF a few times to crosslink the
gelatin         molecules a tidge. don't overdo this, or the gelatin will
be used up.  I would also     air dry the sections at 37C no less than
overnight, in a flat positon, and prefer     longer drying several days to
a week.  
3.  Try adding 10 ml of your stock subbing solution directly to a 2 liter
water bath       rather than coating the slides
4.  Try 100 bloom gelatin instead of 275 bloom, you may get the same
holding but less      background with the smaller gelatin molecule
5.  We started using Plus charge slides (Erie), cut with a very sharp knife
to have     flat sections, drain well and dry flat (same as above) with as
good a success as     gelatin subbed (275) slides for our paraffin
sections.  I am not sure how large     your sections are??  Bigger slides
may mean silaning them inhouse.  

Sometimes we just lived with it, particularly with H&E, as it didn't seem
to mess up the stain on the tissue, just added some color in spaces where
there was no tissue, just the gelatin on the slide???  Is that where you
see it??  I wasn't so nice for photos, but didn't seem to mess up overall

Hope this helps, been there, seen it ---

Date: Fri, 14 Jul 2000 08:53:32 -0400
>From: Mary Stevens <>
>Subject: Gelatin/Chrome Alum for bone
>X-MX-Comment: QUOTED-PRINTABLE message automatically decoded
>Hi all,
>For years, I've been using the same Gel-Chrome Alum Concentrations/methods
to coat slides for undecalcified bone (for MMA) - lately we are getting an
overall background staining on the slides (not clumping, but what appears
as too much gelatin.)  The obv
>cal error in concentrations.)
>Our recipe is:
>1000 mL of 1% gelatin, Bloom 275
>38 mL of 4% Chrome Alum
>Thanks, and have a great weekend.
Gayle Callis
Veterinary Molecular Biology
Montana State University
Bozeman MT 59717-3610
406 994-4705
406 994-4303

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