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Soapbox: Carpet Care - Wet or Dry?
Dry Extraction Cleaning is often maligned and little understood, Geoff Greeley - Vice President of Market Development and Support, explains...
These days the majority of industry experts should really be called wet extraction cleaning experts. Their understanding of dry extraction is on a par with a trombone player explaining how to play a violin - he knows music and music theory; but if he hasn't played a violin, he will operate it improperly yet still expect to hear music!
Dry extraction is often maligned and little understood. Let's put the record straight. The major difference between dry extraction and wet extraction is the amount of water & detergent used per square foot and the technology of how the liquids are controlled.
The term extraction means removal. Both dry and wet extraction systems remove the sticky dirt and spots from the carpet by vacuuming. The critical differences are the type of vacuuming that is done, the amount of liquid used during the cleaning procedure and how the liquid is controlled to prevent soil from running deeper into the pile.
For example, dry extraction vacuuming is done with simultaneous pile lifting and vacuuming; a teaspoon of liquid is used per square foot of carpet; and the liquid is controlled by moistening tiny 'sponges'.
So how does carpet soil? Carpet pile, cut or loop, makes the fabric a vertical surface, (wood flooring is a horizontal surface). Once installed, the carpet begins to do its job of trapping and holding dirt, dust and allergens which are brought in from outside on people's shoes. Research has shown that the majority of the dirt on a carpet is carried in on shoes from the outside or from hard surfaces inside.
This dirt can be divided into two categories... dry dirt and oily (oil base), sticky (water soluble) dirt. The dry dirt represents up to 85% of the total dirt that is walked in on people's shoes. The oily, sticky dirt represents about 15% of the total. So carpet maintenance strategy concentrates on the most highly trafficked areas of the carpet in order to keep the whole carpet clean. The dirt will build up where people walk.
The objective of cleaning is to remove this dirt before it is tracked by shoes farther and spreads throughout the facility. This involves vacuuming/pile lifting as well as chemical cleaning. The HOST Dry Extraction System does both.
Dry extraction cleans carpet using a controlled amount of liquid. The liquid is typically a blend of water, (mostly), and a small amount of detergent and other green cleaning chemistry. Green Seal certified dry extraction methods today do not contain any petroleum solvents. In the past some did contain a small amount of solvent; but today these have been eliminated in favour of green cleaning chemistry.
This controlled amount of liquid, roughly one teaspoon per sq. ft., is enough to dissolve the dirt, but not enough to lose control of it deeper down into the carpet pile. While this small amount of liquid dampens the carpet during the cleaning procedure, (the amount of liquid @ one teaspoon per square foot compares to 40 times that amount with typical wet extraction systems), the carpet is dry and ready for traffic when the cleaning is done - hence, no downtime and no wicking.
The millions of small, absorbent particles dampened with the right amount of water, detergents and green cleaning chemicals control the liquids at all times during the cleaning process. The objective is to avoid soaking the carpet or causing wick back of spots and soils a day or two after cleaning. The HOST Dry Carpet Cleaner is just like a sponge you might use in your kitchen to wipe up spills on a table or counter. When you pass the sponge across the surface, it lays out a film of cleaning agents, which dissolves the soil. Everything that is dissolved is absorbed and trapped in the sponges so it can be removed by vacuuming. This is the controlled and efficient way of removing dirt and spots from a carpet.
Proper cleaning with a dry extraction system involves a machine designed for the purpose plus the cleaning 'sponges'. The dual counter-revolving brushes of the HOST machine open and lift the carpet pile allowing for more effective removal of the deep-down, dry dirt. The powerful vacuum deposits this dirt in a bagless hopper. After this thorough vacuuming/pile lifting, the sponges are applied to the carpet. The machine brushes the moist Dry Carpet Cleaner up, down, over and around the carpet fibres so they contact all surfaces of the soiled fibres, breaking the oil or sugar bonds and wiping the soil away.
The sponges absorb the dirt and spots and holds them. After brushing in several directions so as to bring the sponges into contact with all surfaces of the dirty carpet yarns, they are then vacuumed, (extracted), out of the carpet with the HOST machines powerful vacuum.
29th August 2013