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Posted by Bill S on October 21, 2006 at 10:02:46 am EDT
In reply to Re: Feather question posted by Blackbeard on October 21, 2006 at 7:34:42 am EDT

Ok, Alfred (wonder how many of the younger generation remember who Alfred E. Neuman is, and how he originated?) -

First the temperature question - There is no industry standard for rating the temperature comfort zone for sleeping bags. The crude way is to just measure the loft of the bag (actually pretty good when you calibrate it for yourself). But this does not take into account whether the bag is "sewn through", or one of the various construction methods - box, V-channel, offset, etc etc etc.

Some companies have used instrumented dummies (I think REI does this). Some just send people into the field (I recently tested a bag as part of a group of folks this way). Problem is, again, how do you control for personal factors, fatigue, recent meal, variations in the pad underneath, in a tent (what kind of tent - mesh, single wall, double wall...), wind and breeze, humidity, etc etc. Some have people sleep in a controlled room.

There has been an ongoing effort in the industry to standardize, but this hasn't reached any kind of conclusion.

Lots of companies use guidelines that were published by the US Army 60 or 70 years ago (during or just after WWII). The way the data for that were obtained is now considered highly suspect for reliability.

Bottom line is that some companies are very conservative in their ratings, and very consistent (Feathered Friends, Western Mountaineering). Some are very optimistic (most of the mass market bags). The rest fall in between, with the quality manufacturers being close to the conservative end.

So the simple answer is - there is no standard, and companies publicize whatever number sells the most bags.

Down leakage later.

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