Gill's hematoxylin is an alum hematoxylin. It may be used in progressive or regressive staining methods on histology preparations. Gill's can also be used in cytology staining applications, but cytology material must be fixed in 95% ethanol for at least 10 minutes prior to staining to avoid unsatisfactory staining results.
Gill's hematoxylin is available in 3 different concentrations:
- Gill 1 - regular strength used in cytology staining
- Gill 2 - double the strength of Gill 1 and can be used for cytology and histology
- Gill 3 - triple the strength of Gill 1 and is used primarily for staining tissue
Because Gill's is made with water and ethylene glycol, auto-oxidation of the stain is typically prevented over months. This characteristic makes it more stable than Harris' hematoxylin. However, the nature of Gills is such that extra-nuclear staining may occur. Mucin and even adhesives used on the slide may become heavily contaminated with Gills.
