If humidity drops below 40%, the result to films will be:

• A. Swelling of the emulsion
• B. An increase in static marks
• C. Increased fog levels
• D. Increased brittleness of films

Answer: (D)

Low humidity makes the gelatin emulsion and film base lose moisture and become very brittle. When the film is handled or bent, the lack of water within the gelatin reduces its elasticity, so cracks and chipping can occur along the emulsion layer and around the edges. This is the most noticeable and likely result when humidity drops below 40%, which is why increased brittleness is the correct outcome.

Swelling of the emulsion happens with more moisture in the air, not less. Increased fog levels are related to processing conditions and exposure factors rather than humidity alone. Static marks can appear in dry air due to charge buildup, but the physical integrity issue—brittleness and cracking during handling—is the primary effect described here.