Dear Robbin,

>  	I am looking for a protacol for enhancing DAB with osmium. Does this
> exist? I thought I had seen it on the Histonet some time ago.
> Thanks in advance

Try this:

1.	After DAB/H2O2 rxn, keep in water,
2.	Go to EM lab, Under a chemical safety hood open jar of Osmium 
Tetroxide (diluted in water) and wave slides over the jar or place in 
a diluted osmium solution (try the waste solution) for a minute or 
so.
3.	Replace slides in water,
4.	After a further rinse in water, continue with the counterstain. 

The DAB appears black rather than brown.
Beware Osmium is toxic stuff.

regards, Tony
Tony Henwood
Senior Scientist
Anatomical Pathology
Royal Prince Alfred Hospital
Sydney, AUSTRALIA

http://www2.one.net.au/~henwood
http://www.pathsearch.com/homepages/TonyHenwood/default.html