On Thu, 24 Feb 2000, Forney Constance M Civ 74 MDSS/SGSC wrote:

> Also - my pathologist wants his DAB to stain black instead of brown
> - anyone have a procedure for that ?

  This is done by including cobalt or nickel ions in the 
  DAB-containing incubation medium. Any textbook should 
  have a recipe. The colour of the oxidation product is 
  blue-black instead of brown. There are also silver
  methods for amplifying the brown product, but these are
  quite complicated procedures.

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1