Which factor reduces line strength by 40 percent due to surface staining?

• A. Friction heat
• B. Rust stains
• C. Sunlight exposure
• D. Chemical exposure

Answer: (B)

Rust stains are a sign that iron-based corrosion has interacted with the line. The iron oxide from the rust, along with associated moisture, can transfer to the rope surface, abrading fibers and promoting chemical weakening. This surface contamination can cause microcracking and internal damage that significantly lowers strength—often described as a reduction of up to about 40 percent in the affected fibers.

Friction heat involves damage from rubbing and heat buildup rather than staining, so it doesn’t explain a loss tied to surface discoloration. Sunlight exposure causes gradual UV degradation over time, not a direct consequence of staining. Chemical exposure can degrade fibers but, again, isn’t specifically tied to surface rust staining. Therefore rust stains best account for the notable strength reduction linked to surface contamination.