At 1 point, I used to have the rugs in my office building professionally shampooed two times per year.
It was the only way to ensure heavy-duty carpet cleaning. Although the idea has evolved a bit over time, it still involves a foaming substance applied and worked into the carpet with a brush. The brush helps to remove contaminants from the carpet fibers. The carpet is then vacuumed to get rid of the shampoo, debris plus any excess moisture. The carpet requires quite a bit of effort to dry plus needs to be dry vacuumed to wash up any remaining residue. The process had to be tied up for after the close of typical business hours, allowing the carpet to dry overnight. Over the last few years, the professional cleaning supplier has changed from carpet shampooing to encapsulation. This type of cleaning idea uses synthetic foam detergents. The detergents are worked into the rugs through a machine with a brush. As the foam crystallizes into a powder, it encapsulates dirt in the rugs. The powder and contaminants are then vacuumed up. There are pros of encapsulation over shampooing. It uses less water plus takes less time to dry. It also leaves no film on it. However, it’s not as efficient on heavily soiled carpets, and every now and then, I still insist that the cleaning dealer shampoo the carpets of my building. I want to be sure that there aren’t grime, dirt or other allergens trapped in the fibers.