Extraction of haemalum must mean that the aqueous medium
is acidic. The acidity might be there initially (it's
a good thing for some stains). It may come from 
atmospheric CO2 (distilled water usually has pH=5 for
this reason), or it may be due to aluminium and sulphate
ions coming from the stained section. (All haemalum
solutions contain a large excess of aluminium
sulphate over & above the amount that complexes with
haematein; this is necessary for the stain to work
properly.)

Suggested remedy:
After counterstaining, blueing and washing, rinse the 
sections in a slightly alkaline buffer. (Phosphate, 
pH 7.4 should be OK.) Then shake off excess buffer 
and apply the aqueous mountant and coverslip.
-- 
-------------------------------
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
   kiernan[AT]uwo.ca
   http://publish.uwo.ca/~jkiernan/
   http://instruct.uwo.ca/anatomy/530/index.htm
_______________________________
"Till, Renee" wrote:
> 
> Hello. We have been doing some Oil Red O stains on cryosections of aorta
> and have been having problems with the hematoxylin leaching out during
> mounting. We have tried several different aqueous mounting medias and
> none have corrected the problem. Could it be the tissue or maybe the
> type of hematoxylin? Another lab has been doing the stain on liver and
> hasn't had any problems.

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