Debbie,
we were having problems with our Congo Red also.  What we started doing was
cutting controls as we needed them.  We also made our solutions fresh every
time ( we make up our stock Congo Red solution the day before and let it
stand overnight).  The procedure we switched to is the Alkaline Congo Red
method on page 132 in Frieda's book.  We noticed less yellow-orange
birefringence.  We think that the solutions were breaking down too fast.
Although it is a pain to make up the stock Congo Red solution, our results
are worth it.

Joe Nocito, B.S., HT(ASCP)QIHC
Histology Supervisor
Christus Santa Rosa Hospitals
San Antonio, Texas




> -----Original Message-----
> From:	Jennings-Siena, Debbie [SMTP:ds.jennings-siena@baylordallas.edu]
> Sent:	Thursday, January 13, 2000 9:41 AM
> To:	'histonet@pathology.swmed.edu'
> Subject:	Congo Red Stain problems
>
>   Hi everyone,
> I would like to ask if anyone knows why amyloid on Congo Red stain would
> birefringe as a orange-yellow color instead of apple green?  We are using
> the same procedure that we have used for years.  Our procedure is a
> Puchtler
> Modification.  If anyone has any ideas, I would appreciate hearing from
> you.
> Thanks in advance.
>
> Debbie J. Siena, HT(ASCP)QIHC
> Histopathology Manager
> Baylor University Medical Center
> Dallas, TX 75246
> 214-820-2465