1. How Carpets Soil

Dirt particles carried into a building on the soles of shoes by air currents are deposited on the carpet surface and stick to the pile fibers. These dirt particles are held by mechanical forces in the yarn structure or by adhering to the fiber surface because they are sticky (oily) themselves, or because the fiber is sticky, damaged, or has other sites where soil can lodge.

There are two main types of soil (dirt):

Type 1 - coarse, dry, heavy soil-eg sand, fibers, salts etc-which causes carpet "to fill up with dirt", and which is deposited as far down as the roots of tufts
Type 2 - fine, sticky, lightweight soil-eg soot, oil, rust, etc-which causes most of the discoloration of the carpet surface and makes the carpet "look dirty"

These two kinds of dirt have to be removed using different techniques:

Type 1 - By mainly mechanical mean- eg vacuum (suction) cleaning
Type 2 - by mainly chemical means- eg shampooing, or impregnated compound cleaning

The more carpets soil, the more difficult, and often expensive, it becomes to clean them. It therefore makes sense to try to reduce the rate at which carpets soil by trying to reduce the amount of soil reaching the carpet. This can be done by taking preventative measures such as the installation of adequate lengths of entrance mats, and by good housekeeping- eg by preventing spillages, and by putting mats in lifts and in front of drink dispensing machines.

2. Maintenance Planning

The importance of properly planning a maintenance program for the carpeting in a building, however large or small, cannot be over-emphasized. The maintenance plan should take into account foot traffic loads, traffic patterns, desired appearance levels of the carpeting in different areas of the building, building occupation, the personnel responsible for the maintenance, available equipment, and- cleaning costs.

Carpet Maintenance usually consists of two categories:

• Regular
• Periodic

Correct and regular maintenance will be cost-effective and also increase the life span of carpeting.

2.1 Regular Maintenance

This is usually carried out on a daily basis. It comprises vacuum (suction) cleaning of all regularly trafficked areas, and spot removal. Extra care must be taken of the most heavily used areas. Areas of minimal use can be vacuumed at a lower frequency, for instance twice weekly.

Spills should be attended to as soon as possible- the older the stain, the more difficult it is to remove.

Spot removal kits containing all the tools to tackle spills likely to occur must be available to maintenance personnel, who must be trained in the use of these kits and have access to the kits at all times during the carpet maintenance periods. (see section #4)

It is important to check that the chemicals in the kits are compatible with the carpet installed. Applying them must not cause color bleeding or bleaching or any other damage to the carpeting.

Spot removal chemicals must be used with proper precautions. When used, the area must be well ventilated, the agents should not come into contact with the skin or fumes be inhaled. Those which are flammable must not be used when the operator is smoking, or near open flames, sparks etc.

The recommended spot removal procedure is as follows:

• Scoop up solids and blot up liquids first-avoid rubbing the carpet surface
• For unknown spots, apply solvents (for greasy/oily stains) first, followed by water-based spot removal agents. Apply agent to clean towel or tissue, not to the stain. Use small quantities at a time- always work from edge of stain inwards towards the center. If at all possible, as a final treatment, rinse spot with clean water-do not over wet- and blot as dry as possible with clean tissues or towels.

Spot and stain removal kits should at least contain the following:

• Clean tissues and/or towels
• Small brush, spoon (or spatula) and sponge
• Solvent for removing greasy/oily stains
• Carpet shampoo
• Amyl acetate/nail polish remover
• Laundry detergent
• Chewing gum remover (solvent or freezing type)
• Neutralizing agents: acetic acid solution, ammonia solution (5%)
• Methylated spirits and turpentine or white spirit
• Rust remover

For details on how to remove different spots see Table 1.

Table 1
Spot or Stain Removal Guide for Wool Carpets

The charts below contain methods of treating spots and the order in which they should be tried:

Easy Spots- these are spots which can be easily removed and attended to quickly
Difficult Spots- these are difficult to remove and may require repeated attempts

Some chemicals are hazardous and should only be used strictly in accordance with their use and safety instructions

2.2 Periodic Maintenance

However meticulously regular maintenance is carried out, the time will come when the carpeting will require a thorough, deep or restorative cleaning.

Prior to commencing these wet cleaning techniques, the carpet pile is usually treated with a pile lifter, which is a twin-motor vacuum cleaner with a large cylindrical brush and powerful suction action to open up the pile and remove embedded grit which normal vacuuming leaves behind.

> Spray extraction cleaning injects a detergent solution into the carpet pile, immediately followed by an integral wet pick-up system. Amount of solution sprayed into or on to the carpet pile varies greatly between machine models and makes, and this affects both the efficiency of the "flushing" out of the dirt and the chance of inadvertently over-wetting the carpet.

Cleaning efficiency can be improved by pre=spraying the carpet with the low foam shampoo prior to spray extraction. With all wet cleaning techniques, it is important to avoid over-wetting the carpet as this will greatly lengthen the drying time and may cause problems with discoloration of the pile. Brushing of the pile should also be kept to a minimum, especially with some carpet constructions. It is strongly recommended that the carpet be pre-tested prior to commencing any wet cleaning to ensure that chemicals being used (shampoos or spot removal products), not the cleaning technique itself, will not cause damage to the structure or color of the carpet.

3. Recommended Cleaning Methods for Wool Carpets

There are no hard or fast rules on which cleaning technique is the best for wool carpets. This depends largely on the type of carpet concerned and the degree of soiling. As general rule, cleaning methods involving brushes or beaters should be avoided on long pile or coarser loop pile wool carpets. In these cases, plain suction vacuum and spray extraction wet cleaning are often the best methods but much will depend too on the skill of the operator- no technique is completely foolproof.

The damage done to carpet in (wet) cleaning usually relates to over-wetting too much mechanical action and the use of unsuitable shampoos and other chemicals.

Wet cleaning has both positive and negative effects on the texture of carpets. The positive effects are:

• Lifting of the carpet pile (all textures)
• Improvement in tuft definition (cut piles)
• Improved handle (all textures)

All wet processes cause some untwisting of yarn in cut pile carpets, depending on amount of moisture applied, mechanical action, degree of "settling" of the yarn, etc. Brushing causes fuzzing (shampooing, but also upright vacuum cleaner). Ridging on extremely long pile carpets can be caused by some spray extraction cleaning tools.

EFFECT OF WET CLEANING AND ACCIDENTAL SPILLAGE ON WOOL CARPETS

4. Cleaning Chemicals

The basic requirements of cleaning chemicals for use on wool are:

• Low alkalinity
• Non-sticky residue on drying
• Good cleaning power
• No added bleaches, dyes etc.

The reasons for these requirements are:

• High alkalinity (often, but not always, reflected in high pH) can cause color bleeding with dyed or heather yarns, and in extreme cases, yellowing and weakening of the wool fibers
• Sticky residues cause quicker re-soiling
• Poor cleaning performance necessitates excessive mechanical agitation of the pile
• Additives can cause uneven cleaning results, bleaching or change of colors.

Some commercially available carpet cleaning chemicals are unsuitable for use on wool carpets because they do not conform to one or more of the above requirements.

All materials needed for proper care and maintenance are available through Wools of New Zealand. To obtain a list or to purchase these materials please call 800-367-0462 or go to www.woolsnz.com.