Yes, both get screwed up if they're in ammonia too long.  You might notice
the eosin looking weak before anything else.  Can you adjust the processing
times so they don't come out so dry (then you might not need to use ammonia
water so often).

I remember when I worked for Impath, they made a rule that you had to ask a
lead tech before you could use any ammonia water.  At some point someone
will forget a block there and ruin the specimen.  I don't think it's always
appropriate to use ammonia water either.  For something that is
overprocessed/dry or bloody, its a great trick.  You shouldn't have to use
it too often though.

Mark T.

On Sun, Feb 24, 2008 at 6:09 PM,  wrote:

> I recently asked this on the histonet, and would like to get some more
> info
> on it.
> Could soaking faced paraffin blocks in ammonia water too long negatively
> affect the H+E stain?  I
>
> Could ammonia change the acid/base charges or pH of different tissue
> components that could negatively effect the charges necessary for heme
> staining, or
> eosin?
>
> Thanks for letting me "rerun" this question
>
>
>
>
>
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