One of the most common misunderstandings cleaners have when cleaning carpets is the role of the carpet extractor. Many cleaners regard it as a magic machine that can be run over carpet to remove soil without any real regard to what is actually taking place where the solution meets the fiber. As a result, many are left with carpets that look almost worse after cleaning.
To get the best results out of your extractors, it is important to understand a few basic concepts about what you are cleaning. First, there are two types of soil in your carpet: dry soils, such as sand and dirt; and sticky, oily soils, such as grease, tar and asphalt residues.
One of the first mistakes that cleaners make is failing to remove the dry soils before they begin cleaning. If you learned anything on the playground in elementary school, you probably learned that dirt and water make mud. Well, that “playground science” also applies to the carpets you clean today. If you do not remove the dry soils from the carpet before you begin cleaning, they make mud in your carpet.
You may think that your extractor should remove this soil even if it is wet; however, no extractor (even a truck mount) is designed with that in mind. Keep in mind that dry soil represents about 79 percent of the soils in your carpet, therefore you will remove the bulk of the soil from your carpet by simply vacuuming.
So, what about the other 21 percent? That is comprised of the sticky, oily soils that are tracked into your facility. These soils are typically the ones you visually see that cause you to say, “The carpet is dirty.”
Besides not vacuuming before extraction, another common mistake that cleaners make is to simply wheel their equipment to the location to be cleaned, plug it in and begin cleaning. With most extraction equipment, this means that the chemical will have about one second of contact time with the soils it is supposed to remove from the fiber.
In many cases, it will have been three to six months—or longer—since the last extraction. This is simply not enough time for the chemical to do its job of removing the sticky, oily soils from the fiber. Coupled with failure to vacuum and remove dry soils, this results in a carpet that really does not look any better.
So, how can you raise the performance of your extractors? As we have discussed, you need to vacuum first—and not just a quick, cursory vacuum. Remember, vacuuming with a properly operating vacuum removes up to 75 percent of the soil in the carpet. This step is by far the most critical to your success.
When it comes to the chemical action, dwell time is an important step that is often overlooked. After vacuuming on synthetic carpets, apply a good alkaline pre-spray (per most manufacturers’ instruction, nothing over a 10pH), agitate it into the fibers in heavily trafficked areas and allow it to dwell for 10 to 15 minutes. Pre-spray only as much area as you can clean in that time; do not allow the pre-spray to dry on the carpet.
Dwell time is important because it allows the pre-spray to either emulsify or surround and suspend the soils that are stuck to the fibers. Given 10 to 15 minutes of dwell time, the soils are removed from the fibers and the extraction step is one of simply flushing the emulsified or suspended soils out of the carpet along with any associated residues.
Lastly, all carpet extraction methods leave behind residues, which can lead to carpets re-soiling as the sticky residues capture soil from shoes and other sources. While many try to rinse their carpets with water to minimize this, water is not effective for removing residues. Rinsing with hard water will remove 15 percent of the residue; rinsing with soft water will remove 30 percent; but rinsing with an acid rinse or neutralizing rinse will remove over 90 percent of the residues.
Remember, effective cleaning is a combination of the right processes, the right equipment and the right chemicals. Using all three will give you the best results possible.
The 5 Principles of Carpet Cleaning
1. Dry soil removal
2. Soil suspension
Most cleaners start at number three. They simply wheel in their equipment and start extracting.
However, if you follow the principles in order, the bulk of the soil is removed in the vacuuming step. Most of the remaining soils are removed from the fiber through emulsification or suspension in the next step, which means that by the time you reach the extraction step, the soil removal is essentially done!
Thus, done properly, your extraction step is simply flushing those soils out of the carpet pile.