How Increased Airflow & Low Moisture Lead to Cleaner Carpets
One of the most common topics I see on the ICS bulletin board (www.icsmag.com) and get from cleaners is that of drying times for carpet and upholstery after cleaning. It surprises me the number of cleaners that report drying times in excess of 12 hours or more. When I responded to a post about drying times by stating that my average time with a rotary extraction tool and a truck mount was about 90 minutes, I got a reply from a cleaner that felt that 12 to 18 hours was more realistic. I can’t imagine what he is doing or not doing to leave a carpet damp that long.
Getting freshly cleaned carpets dried is not difficult if you pay attention to several factors, one of which is the amount of water left in the carpet. Often, someone will make the observation that the carpet was overwet, but I feel strongly that it was more likely underdried. A related problem that goes with slow drying is wicking of soils and/or spots. If the soils and spots are removed thoroughly, then they won’t be present to wick back up during drying. Conversely, if they are not removed, then they may come back to haunt you. This seems to be more of a problem in commercial cleaning situations since one may not have control over the other factors of drying, which include air flow and reduction of relative humidity in the areas cleaned. There may be no windows to open for airflow, and HVAC systems may be computer controlled. This leaves cleaners unable to activate these systems for airflow, and in some cases, the removal of moisture evaporating off the carpet during drying is impaired.
There is usually some disagreement among cleaners about whether it is best to dry with inside air and an air conditioner to dehumidify, or to dry with outside air. Here in Florida, which has a semitropical climate, I find that outside air is more effective for drying than an air conditioner. Opening windows and doors during the cleaning and drying processes helps me to regularly achieve quick-drying results. Supplementing the natural airflow with ceiling fans also helps. I don’t have to tell you that this also results in happy clients.
I regularly hear accounts of drying times of 3 to 5 days by some of the large franchises that prefer to run the air conditioner. The science of drying, psychrometrics, may indicate that using the air conditioner to dry carpet is most effective. However, my experience tells me otherwise, especially if the structure can be opened for air exchange.
All science and number crunching aside, the real key to rapid drying lies in the technician’s ability to leave the carpet as dry as possible after cleaning. Spend more time extracting water by making extra drying passes whether you use a power head (such as a rotary extractor) or a wand. Extra drying passes to remove more water means there is less water to evaporate from the carpet, which in turn achieves a dry condition.
Whether you open the structure for natural airflow, add ceiling fans or utilize turbo dryers, drying times decrease if air in the structure is moving across the fiber surface, picking up moisture as it goes along. Some situations may even require the use of auxiliary dehumidifiers to accomplish rapid drying.
MLM and VLM ProcessesThe simplest way to accomplish rapid drying may be to use a minimum moisture method (MLM) or a very low moisture (VLM) process to clean the affected areas. What are these MLM or VLM processes?
MLM and VLM include such techniques as bonnet or pad cleaning, dry foam extraction cleaning or even dry compound cleaning. Each is higher in agitation than most hot water extraction (HWE) systems and relies on the agitation factor for soil removal. The added advantage for the cleaner, besides less probability of wicking, is that they often are higher production processes (more square feet per hour cleaned equals more dollars per hour). Everyone should be interested in that equation since I don’t know anybody that cleans carpet because they love it so much! Most of us are in this field to make a living and a future, like buying a house and putting children through college.
I hope this discussion helps you get a handle on drying. Don’t forget my old mantra: Get it Clean and Get it Dry! Until next month, seeya!