- THE MAGAZINE
Basically, here's how the system works: like any properly applied method of cleaning, it starts with dry vacuuming and preconditioning, in compliance with the principles outlined in the IICRC S100 Standard and Reference Guide for Professional Carpet Cleaning. Following vacuuming and light preconditioning - about 1/2 gallon per 1,000 square feet - the unit is ready to clean using STE. Skeptic that I am, I tested this new unit in my own 20,000-square-foot conferencing facility before drawing any conclusions.
The machine itself is built on one of the company's battery-powered, walk-behind hot-water extraction units with a 21-gallon fill and recovery capacity, but that's where the similarity ends. The STE head has two rollers with a durable nylon fiber bonded to them. The 6-inch diameter, 22-inch-wide rollers look a lot like the fleecy paint rollers designed for textured surfaces.
Here's how the system works:
Following vacuuming and preconditioning, the unit is filled with hot rinse water and appropriate detergent. As with any method of cleaning, chemistry remains an important fundamental with STE.
The speed-control dial is set at about 100 feet per minute for average soil. You can go slower for heavier soil and faster for light soil. When the handles on the unit are rotated forward, the battery activates the self-propelled drive mechanism, causing the machine to move forward or backward (it cleans in either direction).
Eighty-five percent of commercial carpet is produced in a very low level-loop pile design. The two counter-rotating rollers, each spinning at 400 rpm, wipe the preconditioned and suspended soil from the carpet's surface onto the nylon rollers, which is where the STE concept comes in.
The soiled nylon fiber on each roller is sprayed with the hot rinse solution at a rate of about 1/3-gallon per minute. With a 21-gallon solution tank, this provides about an hour of cleaning before the need to refill arises.
Immediately after the rollers are sprayed, two separate vacuum-extraction heads - one on each roller - remove the excess rinse water and transferred soil, which makes the nylon fiber on the rollers ready to absorb more soil with each rotation.
The machine cleans a 22-inch-wide path with about a 2-inch overlap. Results can be seen immediately.
In tests in our conference center, as well as in two school facilities, we got excellent visual cleaning, even on carpet that required two or three cleaning passes. After each cleaning, the extracted wastewater was progressively lighter in color as soil was progressively removed from the carpet. On five 1,000-square-foot sections of commercial carpet, we spent about two minutes preconditioning and six minutes cleaning with the STE process, for a total of eight minutes. That means that one person could produce between 6,000-7,500 square feet of finished carpet per hour.
With a two-person crew - one preconditioning and the other cleaning - it is possible to clean some 10,000 square feet per hour at the moderate speed (100 fpm) setting.
We used two air movers to encourage drying, and a non-penetrating moisture meter to determine the starting moisture content of the carpet before and after cleaning and at 10-minute intervals during drying. In our building, with ambient atmospheric conditions of 74 degrees F and 40 percent RH, we got the carpet back to the starting MC in 20 minutes, even in the overlap areas. In a school building with 78 degrees F and 68 percent MC, drying took around 30 to 35 minutes.
The STE concept, at present, has limited application in our industry. It's relegated to large volumes of commercial carpet only. It is not a replacement for restorative cleaning methods, such as hot-water extraction, but it considerably extends the interval between the need for restorative cleaning.
As one who has struggled to give large-volume commercial carpet end-users a cost-effective, minimal-labor cleaning method with rapid drying time, I see this technology as an answer to a major need. But don't take my word for it; check it out for yourself. For commercial customers with lots of carpet, it's well worth evaluating; even a card-carrying skeptic like me has to admit it is truly a new innovation in carpet cleaning.