I am new to this forum, and relatively new to the hammock scene.

One thing I have noticed since joining HF is that a large amount of topic and discussion centers on UQs, TQs, Pads..........

basically......it is all on

INSULATION.

So, I thought I knew the basics of insulation, but it appears I did not!

Consequently, I did a bunch of online research.

Here are a few things I found. I would suspect that most of this information is not new to most of you. However, I thought I would share and get additional thoughts and opinions.

FIRST: Insulation and how it works:

Contrary to popular belief, insulation is not used to keep cold from entering an area, but only to retard the flow of heat. All substances, whether solid, liquid, or gas, contain some heat, so the condition of cold is merely a condition of relatively less heat. Heat can flow in one direction only—from a warmer body to a less warm body—so insulation serves to retard this flow. In a refrigerator, for example, insulation slows the flow of heat from the room air to the interior of the refrigerator. In a building, insulation keeps heat in during winter and out during summer.

Air is a poor conductor of heat, and when trapped in a hollow area is an excellent insulator. Other insulating materials, some of which depend on air pockets for much of their insulating effect, include mineral wool, fiberglass, asbestos, wood, concrete, vegetable fiber, vermiculite, and foamed plastics such as polystyrene. These substances retard the conduction and convection of heat. Aluminum sheets and aluminum foil, on the other hand, prevent the radiation of heat, by reflecting it back toward its source.


Next: Why materials are better insulators than others:

But what is it specifically about materials like wool and down that provide such good thermal insulation? Why is wool warmer than an equivalent amount of leather or rubber? Why is down so light and yet so warm? The key is the air pockets between the fibers of wool and between the tiny feathers in down.

Like all gases, the air around our bodies is a lousy conductor of heat. The molecules in a gas are far away from each other, and conduction of heat only happens when a faster-moving molecule collides with a slower-moving one, transmitting some of its kinetic energy to the other molecule. Since heat is simply molecular kinetic energy, this transfer of kinetic energy between molecules enables heat to flow through a body from where hotter areas to cooler ones. This does happen a bit in a gas, but much less than in liquids and solids, where the molecules are much closer together.

If the air around our bodies were completely still (and if we too kept completely still), then that air would act as a pretty good heat insulator, and we would stay nice and warm. But air being a fluid naturally moves around, and the movement of air carries heat away from our bodies by a process called convection. On a windy day, the atmosphere of warmer air near our bodies is carried away, and it is replaced by cooler air, thus speeding the loss of heat. That’s why the wind chill factor is a relevant measure of how cool the air feels on a cold, windy day.

But when we wrap our bodies in layers of wool or down, we surround ourselves with a huge number of tiny air pockets. The fibers or feathers between those air pockets block the movement of air from pocket to pocket, thus reducing the flow of heat by convection within the material. Convection can still carry heat away from the surface of a sweater or jacket, but the temperature is lower there than at the surface of our bodies, so there is less heat loss by convection than if we were naked or wearing less insulating clothing.

One famed property of wool is that it still insulates when wet, unlike cotton which only insulates well when dry. Why is this? When cotton gets wet, water fills up the tiny air pockets that otherwise would provide insulation. Because at the microscopic level water doesn’t cling as well to wool as it does to cotton, wool can get wet without its tiny air pockets being filled up with water, so it still reduces heat loss by convection.