Fiberglass has essentially been available throughout history as glass makers have experimented with it since the early 1800’s. However, it was not until finer tooling became available that it was able to be developed into what is commonly known as fiberglass today.
Fiberglass that is now used as insulation wasn’t invented until 1936. In 1938, Russell Games Slayter from Owens Corning began the manufacturing process. The Owens Corning company was the first to mass produce fiberglass insulation and remains the industry leader today.
Manufacturing Process of Fiberglass Insulation
The manufacturing process of fiberglass insulation can be loosely compared to that of cotton candy which it even resembles in looks, but not taste. Cotton candy is made by heating sugar to it’s melting point and then spinning it, which cools it back down and causes it to form its cotton-like shape.
Fiberglass is made by melting down silica sand instead of sugar. The sand melts at a temperature of over 3600 degrees Fahrenheit and is then spread very thin and shot out of a machine with many small orifices, where it is quickly cooled before it has a chance to form an ordered structure. It is then spun into fibers.
Then it is sprayed with binding substances and formed into blankets of varying thicknesses. The R value of insulation is determined by these thicknesses. Insulation with a thickness of 3 ½ inches will have an R value of R-11 and insulation that is 6 inches thick will have an R value of R-19.
The blankets make up the batt products or it is cut into strips for the roll products. If the insulation is to have a paper backing, that is added last. To add the paper backing, the paper is first sprayed with a tar like substance that acts as a moisture barrier and is also used to stick the Kraft paper to the fiberglass.
Loose fit fiberglass or fiberglass that is sprayed in is made the same way except the last step is a large chopper. The material can also be pressed into high density board to make rigid fiberglass sheeting that is used on the outside of homes and can also be made into other structural products.
Using Fiberglass Insulation
Now that you know a little about how the insulation is manufactured, you should understand it’s function better. For instance, the vapor barrier of the insulation, that is spayed on the paper side of rolled insulation, should face the warmer side and the loose side should have house wrap to protect it from the wind. Another thing to keep in mind when insulating you home is this: If you smash six inch thick insulation into a three inch space, you are not increasing the R value at all.
Actually, you would be lessening the R value by crushing it. Fiber glass insulation works due to the amount of air it holds, not the density of the fibers. So, whether the fiberglass insulation is loose fitted in the attic, rolled between the studs of a wall, custom blown into the walls, nailed on as rigid sheeting or batts rolled out under the floor joists, you now hopefully know more about it than you did before you read this article.