Bluing Reagent may be used following hematoxylin to "blue" or alter the shade of hematoxylin from a purple to blue. Nuclei: Purple. Nuclei after Bluing: Blue. Blue nuclei after Eosin: Blue to Violet. A pH-controlled solution for complete and effective bluing of hematoxylin in histological and cytological procedures. Hematoxylin is a nuclear stain that is used as a counterstain for immunohistochemistry. Together with eosin, it forms the hematoxylin stain (H&E stain), one of the most commonly used stains in histology.
Stain with hematoxylin according to protocol. Place in Bluing Reagent until nuclei are blue (1-2 minutes).