Have you ever had your carpets cleaned in your home or business and the carpet didn’t look as good as you had hoped in the high traffic areas? This could be because your carpet cleaner didn’t do a sufficient job, but it could also be permanent fiber damage. If it didn’t look like there was much of a difference after the cleaning then it was probably not a very good job. That being said, carpet fibers that have taken on damage will appear dirtier than they really are because they no longer reflect light the same way that they did before this damage happened. Similar to scratched-up Plexiglas, light is distorted and will appear much darker than the unscratched Plexiglas. This happens because carpet fibers are essentially made of clear plastic. These fibers are so thin you may need a magnifying glass to see them. They are woven together like yarn to make thicker strands. Sand, dirt, and dust are very small but compared to carpet fibers they are gigantic boulders with sharp edges. The more soiled the carpet gets, the more power this sharp debris has to saw into the carpet fibers, sometimes severing them from their root completely. Compare it to taking sand paper and gluing it to the bottom of your shoes. That is the best analogy I can come up with though to describe what happens when these particles collect in large numbers. Our shoes crush and mash the fibers together, scraping and slashing them with tiny sharp particles. To be honest, it is pretty amazing how well carpet stands up to this, especially in commercial applications. Even worse than dust and dirt are the metal shavings created in machine shops. These particles are like tiny saws and our shoes are the lumberjacks.
The best defense against these microscopic belt sanders is to have the carpet cleaned and protected on a regular basis (minimum of once a year). The cleaning lowers the numbers in the sand and dirt army while the protector creates a thin plastic layer over the fibers that will take the damage instead of the fibers themselves. Much like how wax protects the paint job on your car from flying sand on the roads.