Radiant Barrier Insulation

Radiant Barrier is a space-aged product that is based on the principle of the Dewar Vessel, often referred to as the Dewar Flask. It was invented by Scottish chemist and physicist, James Dewar (thus its name) around the turn of this century. It was developed to contain heat generated in chemical laboratory experiments and re-direct that heat back into the flask.

We are all very familiar with one product that uses this concept. It's called the Thermos¨ bottle. Originally, these bottles were made of silvered-glass and were very fragile, as any school kid in the fifties remembers. They were silvered on BOTH the inside and the outside of the glass. Eventually, in the interest of durability, the bottle was made out of polished steel, but we all know the steel liners just weren't as effective.

Well, Dewar's theory was based on the fact that almost every single material known to man has an R-value, and the "R" only stands for 'resistance'. Regardless of what any one wants to tell you, R-19 does NOT stop any heat at all. It slows it down by absorbing it. But later, when it has reached its capacity for holding heat, it will start giving off that heat, or, what is technically referred to as 'radiating' it. And, it radiates that heat in ALL directions, even, if it's right in the middle of a hot summer and you are trying to keep the heat out of your house. Ever wonder why, when you come home to a house with all its windows opened on one of those cool summer nights, you open the door and the house is still hot. It's because that R-factor didn't STOP anything. It just slowed it down by absorbing it, only to radiate it later, right into your house.

Remember, earlier, I said, "ALMOST every single material know to man has an R-value". There are three that don't. They are gold, silver, and the purest aluminum. That's why Dewar used silver instead of fiberglass to insulate his flasks. Each of these materials "Reflects" between 97% and 99% of the radiant energy that strikes its surface. But gold, silver, and aluminum are also conductors, so in order for the Dewar Flask to work, he used glass as the thermal barrier. Great for the laboratory, but we all know what happens to it on the school playground.

NASA developed a flexible, durable radiant barrier by replacing the glass with a thin film of Mylar and covering it on both sides with gold, silver, or aluminum. Lightweight and very thin, this made a perfect material for insulating the spacecrafts, spacesuits, and satellites.