How do linseed soaked rags dry?

• A. Evaporation
• B. Absorption
• C. Oxidation
• D. Condensation

Answer: (C)

Linseed oil is a drying oil, so rags soaked with it dry by oxidation in air. Oxygen reacts with the oil molecules and, through a slow polymerization, the oil forms a solid film. This is a chemical change, not simply the liquid evaporating away or being absorbed. Because the oxidation is exothermic, the rag can heat up, and if many oily rags are piled together, there’s a real risk of spontaneous ignition. So the drying mechanism here is oxidation, not evaporation, absorption, or condensation. For safety, spread the rags out to dry or place them in a metal container with water to dissipate heat.