Biocare progressive hematoxylin is water-based and is specially formulated for immunohistochemistry. It can be used for both paraffin and frozen sections. Tacha Automated Hematoxylin stain nuclei a beautiful sky-blue and provides the end-user high contrast staining for DAB, AEC, Bajoran Purple and Fast Red procedures. Tacha hematoxylin contains an anti-oxidant, and in most cases does not need filtering. It can also be used on an automated staining system.