Over extended use, the R-value of a sleeping pad does decrease gradually. However, the reduction is so small that it is negligible across the pad's entire service life.
Starting two days after production, we test the R-value of each pad at regular intervals. The chart below shows R-value data collected at different stages for a Mountain Spring egg crate sleeping pad:
The data shows that the R-value drops relatively quickly during the first three weeks. After approximately 60 days from production, the R-value gradually stabilizes, settling at roughly 10% below the initial value at the time of manufacture. This decline is related to the cell pressure within the foam at the time of molding and the chemical composition of the gases trapped inside the cells.
All Mountain Spring sleeping pads are held for a minimum of 60 days before shipment, by which point the R-value has already stabilized. Any further change in R-value over long-term use is negligible within the pad's expected service life.
R-value data at different time intervals
Key Takeaways:
- Over extended use, the R-value of a camping sleeping pad decreases gradually, but the reduction is minimal and negligible across the pad's entire service life.
- The decline in R-value is attributable to the cell pressure at the time of foam molding and the chemical composition of the entrapped gases.
- Mountain Spring sleeping pads are not shipped until at least 60 days after production, by which time the R-value has stabilized. Any subsequent change during long-term use is negligible over the pad's lifespan.