I did the Stephenson Warmlite VBL shirt experiment more than 25 yrs (when they had the nudist catalog
)ago:FAILED. The shirt did retain warmth, but because it was a shirt and a base layer (tried alone:yuk, with polypro underwear:OK, and with fishnet underwear:OK) it was inconvenient to take on/off as conditions dictated, and too much sweat from overheating resulted. This defies the benefit of a VBL. Also, with their second generation shirt with aluminized fabric, it started coming off and made a mess. And, the seam sealing didn't hold up due to movement.
The VBL sleeping bag "sock" liner worked well once I sewed arms on it. The mylar sheet is a vapor barrier, but I don't consider it on the same par as a VBL, since it doesn't created a close body micro climate. It only deflects vapor from infiltrating the UQ, and it did work well in that regard.
How much benefit it provided will be determined tonight when I re-weigh the bag after 36 hours of drying time. No mater how you manage the vapor/moisture problem, some will invariably get in, and degrade the insulation. At some point you will have to dry out.
Bookmarks