How should slides be prepared prior to using Romanowsky stains?

Slides intended for Romanowsky staining must be air dried to preserve the cellular morphology essential for accurate analysis. Air drying allows the cells on the slide to adhere properly and ensures that they are not overly hydrated, which could interfere with the stain's penetration and binding to cellular components. This preparation step is crucial because the effectiveness of the Romanowsky stain, which relies on differential staining of cellular elements, greatly depends on the integrity of the cells.

Other preparations such as immersion in formalin or freezing can alter the cell structure and may result in artifacts that would negatively impact the staining process and the interpretation of results. Coating slides with fixatives is typically unnecessary for Romanowsky stains and may also cause unwanted interactions with the staining components. Thus, air drying is the most appropriate method to ensure optimal staining and clarity of cytological features.