Soiling & Remedies
 

We define soil as anything foreign to the carpet, or that was not part of its original construction. This includes all spills, tracked in soil and other contaminants, in many cases chemicals that were left in the carpet by improper cleaning.

Soil is deposited onto the carpeting in many ways. The three most common are airborne soils, spilled soils and the balance is tracked in dirt and oils.

A significant amount arrives as airborne soil. This soil includes types such as air pollutants that come from factories, automobile engine emissions and break and tire dust, wind generated dust and organic pollens, spores and contaminants. They enter the structure by sneaking thorough entrances and fresh air systems. Some airborne soils inside the space is generated by machinery, copiers, printing equipment, cooking and manufacturing areas. While these particles are reduced by air conditioning filtration much of the material falls to the floor and is trapped by the carpeting.

Spilled soil is one of the most concerning of our problems because it assaults our  visual sense. Most spills can easily be removed if approached correctly. Some if improperly treated can penetrate the fibers changing the color of the fibers and become permanent. These visual stains damage the carpeting and reduce its value. One bad stain in the wrong area can ruin and entire installation.

Tracked in soil comes into the building on the bottom of shoes, on boxes and other shipped and delivered materials and on the wheels of dollies and other rolling equipment. These soils are the carpets worst enemy. Microscopic inspection of these soils shows that they much of this soil is sharp abrasive silicates that scar and abrade fibers. These microscopic abrasions  create sites where other staining agents and soils attach becoming more difficult to remove. The abrasions also distort the reflections of light by the fibers. This makes them look more soiled and worn than they really are. This abrasion over time can  ruin the carpet. 

The soils are further divided into  insoluble (those that are not dissolvable by water and chemicals) and soluble soils.

Insoluble Soils

Much of the contaminants that enter our indoor environments are composed of silica's, metals, carbons and,  organic and synthetic fibers. These types of contaminants represent approximately 80% of the soil that ends up in the carpeting that needs to be removed on a regular basis.  The larger particles are the most difficult to remove and some of the normal nightly janitorial vacuums, especially the back pack style, that has no beater brush,  fail to remove. These particles are the most damaging to the carpet fibers themselves.

The smaller of these   particles ( one micron and under) that end up in the carpet represent the greatest danger to health.  These  particles if reintroduced to the air  can be breathed in and can  lodge deep within our lungs causing irritation and allowing infection. Improper vacuuming using cloth bags or cheap paper bags can just stir up small particles and put them back into the air. Improperly maintained vacuums that have dirty bags can broadcast fungi and bacteria at very high rates seeding the indoor environment with spores and bacteria and create a very un-healthy environment. 

Soluble Soils

These soils (the remaining 20% ) are the contaminants  that can be dissolved by either water based systems or solvent based systems. They are composed mostly of foods,  cooking by-products and cleaning compounds used on the carpet and other surfaces within the facility. In poorly maintained facilities most of these soils were introduced by the maintenance activities themselves.

Soluble soils are often sticky and adhere to the fibers. They in turn attract the insoluble soils and  hold them to the fibers. It is these soluble soils that make regular maintenance necessary.  If it weren't for these soils carpet could be cleaned by vacuuming with a good pile lifter the only maintenance the carpet would need.

Soil Management

The processes of soil management are;

Dry Loose Soil Removal

Soil Suspension

Soil and Chemical Extraction

Nap Finishing

Most loose dry soil can be removed by regular vacuuming. With the addition of a periodic pile lifting the balance of the dry soil can be removed. The pile lifter also helps to open up compacted pile and re-organize the yarns, lifting them up and combing them into alignment. Pile lifting would remove all the soil if it wasn't clinging to the fibers with combinations of static charges and oily and wet sticky soils.

Soil suspension is accomplished in any cleaning by what we call the CATT formula. CATT  stands for Chemicals, Agitation, Temperature, and Time.  This process can be considered as a pie chart with these four parts. Increase one of the sections and you will decrease the one or more of the others. For example increasing the temperature reduces the needed quantity the tree other components. By precisely managing these four components we can produce efficient cleaning. If we do not precisely manage these components damage can occur. Use too much chemicals or too much temperature, or too much agitation and the process can become damaging. Provide too little of one or more components and the cleaning pie shrinks until the result is not sufficient to produce cleaning. This is the science of cleaning.

To describe the function of chemicals in the cleaning process is a little like describing the sound an orchestra makes. It is a combination of actions. A surfactant, a surface active agent, reduces the surface tension of the water and allows the fibers and soils to become wet. This allows the chemicals to move in to wedge by electrical forces the soil away from the fiber in a process call deflocculating. The soluble soils then become emulsified into the cleaning fluid and the insoluble soils become sequestered or  separated from the fibers and held in the solution awaiting removal. Alkaline builders in the surfactants soften the water allowing them to accept more contaminants. The alkalinity aids in emulsification and turns fats and oily soils into water soluble solutions. Dirty solvents additives of alcohol glycol base increase the speed of this emulsification.

Agitation accomplishes a couple of important things. First, agitation homogenizes the chemicals used and improves their contact with all sides of all fibers. Proper agitation also organizes the yarns, helps separate them and improves the chemical's deflocculating of the soil. Agitation is accomplished by manual agitation with a gandy brush, this can be good but it is a lot of work to accomplish. 

Some antiquated approaches use the old rotary floor machine fitted with a shampoo brush. This is called rotary shampoo and even dry foam extraction by some companies.  This process is way too aggressive on the carpet. The rotary  floor machine was designed to scrub hard floors and needed a lot of  weight for good scrubbing performance. Unfortunately,  this weight when used on carpet, must be supported by a very stiff brush that will not crush. This combination of heavy machine and stiff brush is too aggressive on  carpeting, especially cut pile. It can damage the carpet and  voids some manufacturer's warranties  so beware of this system. 

The bonnet system (aka electrostatic, semi dry, chemdry) is used as an agitation system, and, when used with the proper chemicals it can achieve  a good surface agitation and good surface dirt absorption. 

The best method for agitating the carpet is the reel type brush found on pile lifters and other carpet maintenance equipment. This equipment allows adjustment of the brush for controlled agitation. It also helps comb yarns back into good organization and opens crushed carpet up for better chemical and extraction penetration.

Temperature increases the speed of the chemical reactions. For every 20 degree rise we have a doubling of the effect of most cleaning processes. It is important to not use too much temperature however as the fibers can become damaged or altered by high temperatures. The optimum temperature to operate general cleaning is around 140 to 160 degrees.

The last component of soil suspension is Time. Chemicals take time to accomplish their work. This is called dwell time. If the chemical strength and temperature are raised then the time to accomplish the cleaning decreases. If the dwell time is increased then the strength of the chemicals and/or the temperature can be decreased to accomplish the same degree of soil suspension.

After the soil is suspended come soil and chemical extraction. The most effective process for this step is rinse extraction. It not only removes the soil but also rinses the chemicals used in the process completely out of the carpeting, leaving the carpeting film free.  

After this step what remains is the nap finishing step. Some procedures use the wand stroke of the extraction equipment as the finishing step. Most good cleaning teams will use a gandy brush to brush the carpet up and leave it standing up.