The present invention provide for solutions of a defined composition useful in a staining protocol, such as a hematoxylin and eosin staining protocol, when used at certain points of the staining protocol. The formulations of these defined solutions are such that carry-over of the solutions will not negatively impact, or preferably, will stabilize or favorably modify staining reagent solutions coming in contact with the solutions. In certain embodiments of the invention, solutions are buffered to maintain a specific pH that when carried-over—such as carried-over into hematoxylin—will not significantly influence the pH of the next staining reagent.