Vapor Barrier Liner
Overview
A vapor barrier liner is a non-breathable layer worn close to the skin to prevent moisture from entering insulation layers in extremely cold conditions.
Key points
- Used primarily in sub-freezing environments.
- Reduces sweat-driven moisture accumulation inside sleeping bags or clothing.
- Improves insulation performance during multi-night trips.
- Requires careful moisture and temperature management.
Details
Vapor barrier liners trap moisture from the body, preventing it from reaching insulating layers that could lose loft when damp. They are typically used in winter camping, high-altitude expeditions, or polar travel. Because they restrict breathability, they can feel clammy or warm and require user familiarity to avoid discomfort. Proper layering underneath enhances effectiveness.
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