[Histonet] Alkaline Congo Red Method (Puchtler et al)

[Evan Dessasau]

Hi.....being new to histology as a carrere I have trouble getting stains 
to look like they do in the book.  The current issue I have is with the 
Puchtler's Alkaline Congo Red.  The nuclear staining is done before the 
alkaline solutions.  At the end of the protocol the nuclei are no longer 
blue. You can almost watch the color change occur in the alkaline salt 
solution.  The protocol calls for 2.5 min. in the Harris hematoxylin and 
then rinse for several min.  I've not found that the nuclei come to a 
good blue color this way and the color fades.  When I follow the 
staining time on the bottle for the Harris, which calls for 10min. and 
then rinse for more like 14 to 21 min. I get very good blue color.  I 
can still watch this fade to a dull color which is unacceptable.  I'm 
using Harris from EMS.  I do filter and I follow the protocol in the 
text Histotechnology: A self-instructional Text by Carson.  What am I 
not doing right ??
Thank you for what ever advice ,
E-van