When using paraffin with a melting point of 55-57 C, what is the most common floating-section water bath temperature?

• A. 40-45 C
• B. 45-50 C
• C. 50-55 C
• D. 55-60 C

Answer: (B)

Floating sections relies on a temperature that keeps the paraffin pliable enough to relax and lie flat, without becoming so soft that the tissue loses shape or the section drags on the water. The paraffin in this case has a melting point of about 55–57°C, so a water bath set in the mid-range around 45–50°C provides that practical balance. At this temperature, the wax remains sufficiently warm to allow the section to float and smooth out wrinkles, yet not so hot that it over-melts, causing distortion, edge smearing, or detachment from the slide. If the bath were cooler, sections wouldn’t float evenly and would wrinkle; if it were hotter, the wax would become overly fluid and distort the tissue or blur boundaries. This is why 45–50°C is the commonly used range for floating paraffin sections with a melting point in the 55–57°C range.