Question: what is the counterstain in the ziehl-neelsen acid-fast stain procedure?
Answer: Step 2: Smear Preparation (Review) ...  Cover the smear with carbolfuchsin dye. ...  Dry heat for 2 minutes. Cool and rinse with water. ...  Wash the top and bottom of slide with water and clean the slide bottom well. Counterstain with Methylene Blue for 30 seconds to 1 minute.