Paraffin wax is composed of hydrocarbons produced by cracking of petroleum and kept how many degrees above the wax melting point?

• A. 0-1
• B. 2-4
• C. 5-7
• D. 8-10

Answer: (B)

Paraffin wax must stay fluid enough to flow around and encase the tissue during embedding, but not so hot that it damages the specimen. Because paraffin is a mixture of hydrocarbons with a specific melting point, the bath is kept only a small amount above that point so it remains molten yet controlled. Keeping it about 2–4°C above the wax melting point provides the right balance: it stays fluid for proper infiltration and edge sealing, while minimizing thermal stress and artifacts in the tissue. If the temperature were only marginally above melting, the wax could begin to solidify as heat is drawn away, leading to poor embedding; if it were much higher, the excess heat could distort morphology or affect tissue components.