Water can be used as a differentiator for eosin. It is common to follow the eosin staining step with 95% ethanol. The ethanol aids with rinsing the slide, while the water pulls excess eosin from the tissue. This step can help with coloration control and is done by extending the time in water or 95% ethanol for lighter stains and shortening the time to maintain brighter coloration. However, excess water in xylene can continue the differentiation process and can be seen after coverslipping as a pink haze on the slide.
