Dear Mary,
We observe the same problem and never found a good solution to prevent it! 
We keep the slides away from direct light and take pictures as quickly as 
we can. Eventually, we lift the coverslip, rinse the section with lukewarm 
tapwater and re-counterstain it with haematoxilin.
Chris van der Loos
Dept. of Cardiovascular Pathology
Academical Medical Center
Amsterdam - The Netherlands

 >Date: 3 Apr 2003 09:45:43 -0600
 >From: Mary Bryhan 
 >Subject: IHC - Hematoxylin fading
 >
 >Does anyone have any problems with the hematoxylin fading from their IHC
 >sections after coverslipping?  We use Mayer's hematoxylin after AEC and
 >mount
 >with Dako's Glycergel.
 >
 >Mary Bryhan