testing a sleeping bag

HOW DO YOU TEMPERTATURE RATE YOUR SLEEPING BAGS?

The above question has been asked of me more often these days than in the past. As the reputation of the Wiggy’s bags has grown with more people purchasing them and telling friends the interest in how I do things has also grown. I am pleased to accommodate answering the question.

I initially read Gerry Cunningham’s booklet “HOW TO KEEP WARM” and in it he had a chart showing the amount of inches of insulation needed for any given temperature and I used it as a guide. After that I made bags that were used in the field without any temperature assigned to them. Once a bag demonstrated at what temperature it performed I weighed the bag. If it worked fine at plus 20 degrees F I weighed it. In my size a regular wide body weighed 3 ¾ pounds and the layers of insulation on the top and bottom of the bag was the 12 ounce Lamilite. That bag today is known as the Ultra Light. I then increased the weight of the Lamilite or decreased the weight depending upon the temperature I was looking for. The process took several years starting in 1976 when I started my first company Olam Outdoor Sports Products.

When I started making the Wiggy’s bags I already had extensive knowledge of what would and would not work for my purposes. The biggest change was moving from that heavily resin boded continuous filament fiber to what I have used since the inception of the Wiggy’s bag essentially an un-bonded product. By eliminating almost all the bonding agent the end product is much softer, significantly more resilient and a far better trapper of heated air. What I did not know was that it also allowed moisture while in a vapor state to easily move through the fibers and out of the bag.

All of the temperature ratings were established with the help of human beings versus a copper manikin. During the 1980’s all of the domestic manufacturers of sleeping bags such as North Face, Sierra Designs etc. started sending their bags to Kansas State University’s environmental laboratory for testing on the copper manikin. When I heard about this I sent a bag to them as well. The bag I sent was 3 ¾ pounds and the clo reading they gave me which is what you get from them was 4.45. When I called and asked what that equated to in F or C I was told they couldn’t give me that information. All of the companies that gave them bags to test received the same information i.e. a clo rating for their bags. I was told that my bag had the highest clo rating for its weight over all of the other bags. I guess I should have been happy knowing that. From that point on I have viewed these tests done on machines as of having no value.

Further when I rate my bags it is always with the understanding that the rating is based upon being in a tent or some form of closure and on a ground pad. Ideally it should be a Wiggy’s ground pad. I always tell people they are not rated being used under the stars. When you are exposed to the air which is moving it will move the heated air above your sleeping bag and eventually you will start getting cold. But when you are in an enclosed shelter such as a tent there is no air movement taking the warmth on the surface of the bag, so you lose less heat and stay warm longer.

To the best of my knowledge when someone walks into a store that sells sleeping bags they look at the marketing companies hang tags for a temperature rating and they read more often than not an EN rating. EN stands for European normal, which I have yet to get an explanation of. If you were to ask the store clerk if the rating is accurate for sleeping under the stars they will tell you yes. They are just concerned with making a sale.

I think it is obvious why so many people over the years have found that they do not sleep because they are cold in a sleeping bag. More often than not I am told by a new customer they are a cold sleeper, I say really, were you actually sleeping when you are cold, the answer always is no. There is no such state one can be in and be a cold sleeper.

In conclusion the only way to actually test a sleeping bag is with a human being and the more the merrier. Based upon all of the comments about my bags keeping people warm it warms my heart.