Dry cleaning of garments with perchloroethylene or petroleum solvents avoids saturating the fabric with water. While the clothes are immersed, the solvent does not penetrate the fibres of the fabric, thereby avoiding the possible swelling and shrinking that can occur with water saturation. The garments are inspected and pre-spotted for stains and heavy soiling by a trained “spotter”. After pre-spotting they are sorted by types of fabric, colour and weight and then machine-cleaned in solvent containing detergent. The solvent is removed from the garments by draining, spinning and tumble dying with hot air. The recovered solvent is filtered and purified for reuse by a distillation process.
A typical wetcleaning cycle consists of numerous successive batch operations using detergents, soaps and bleaches, followed by a rinse operation. As in the drycleaning process, the garments are inspected and, if necessary, pre-spotted.
Garments made of delicate fabrics are immersed in water containing detergent and gently hand washed, while heavier fabrics may be scrubbed. The garments are then rinsed, dried in a machine dryer, or hung dry and finished.
Which cleaning process to use?
The factors determining the cleaning method used whether a garment is cleaned in water or solvent are: The types of soil present. The fibre composition and garment construction.
The dye present in the fabric and the nature of the various trims, linings, or other findings that may be used in the garment.
The various dyes used to colour fibres and fabrics can often determine whether or not an article is washed or drycleaned. In general, man-made fibres are solution-dyed and respond equally well to either process. Dyes used for rayons, on the other hand, respond very poorly to water. Silk and wool dyes often respond poorly to water, and silk garments are normally drycleaned rather than laundered or wetcleaned. Other types of dyes may respond well to water, but not so well in drycleaning solvent.
Types of Soils
There are three basic types of soil:
Water-soluble soils often consist of body fluids, salts, or sugars and are best removed by water. Solvent- soluble soils are oils and greases, including natural oils secreted by the body, that dissolve readily in solvents and are best removed by drycleaning. Insoluble soils do not readily dissolve in either water or solvent and are normally removed by mechanical action and flushed away from the fabric.
Laundering and wetcleaning processes can be modified to remove some solvent-soluble soils with the addition of detergents or soaps. Detergents used for laundering are normally formulated with mild caustic materials. Because only milder detergents can be used in wetcleaning, the process is somewhat limited in its ability to remove oils. Similarly, drycleaning solvents can be enhanced with the addition of detergents to remove water-soluble soils. The degree of removal is dependent on the detergent used and the careful control of moisture during the cleaning process.
Fibres & Fabrics
Fabrics are made of fibres. Many fibres respond well to both wetcleaning and drycleaning. There are exceptions such as wool, linen, silk and rayon which are subject to shrinkage and felting when in contact with water. In addition, protein fibres like wool and silk tend to degrade after contact with even the mildest alkalies found in the wetcleaning process.
Wools also do not respond well to excessive heat typically used in the laundering process. The scaly nature of wool fibres tends to collapse when subject to heat and mechanical action, producing irreversible shrinkage and felting of the fabric. This problem is enhanced in garments with a loose fabric construction, which tend to relax if the article is washed and shrinkage results. These effects can be minimized using a wet-cleaning (i.e., hand washing process.) Most fibre types are compatible with the drycleaning process because drycleaning solvent does not swell fibres and the clothes are cleaned at room temperature.
Trims & Linings
Most garments have trims (e.g., buttons) of some sort that can determine how the garment is cleaned. In addition, various linings and other findings (e.g., felts, interfacing, pads) often are used in garment construction that can present problems when cleaning. If, for example, any differential shrinkage of tailored articles (e.g., men’s suits) occurs during processing, undesirable distortion and puckering can occur. This happens because the felts or linings used in the construction respond differently to the care process than the shell fabric. In general, there is less chance for damage using the drycleaning process in place of wetcleaning.
Finishing processes used after wet and drycleaning vary, depending on the garments being processed, but generally involve steaming and pressing. Steam is used to relax wrinkled fibres. After steaming, the fibres are pressed and cooled to keep them in place. Pressing is the most important step, requiring considerable skill and training. As a general rule, finishing after wetcleaning is more labour intensive than that of drycleaned items.
Many factors determine whether a drycleaning or a wetcleaning process is compatible with a particular garment or textile article. Your professional cleaner, therefore, must use his or her professional judgment to determine which process will restore the garment to a condition that is as close as possible to its “look like new” state.
Most garments labelled dry clean only can be cleaned with water through a process called wet-cleaning. This is a time-intensive process that takes some skill and special equipment. The trick to professional wet cleaning is the computerized operations that allow for precise control when cleaning garments.
The EPA considers it one of the safest professional cleaning methods; its benefits include no hazardous chemical use, no hazardous waste generation, no air pollution and reduced potential for water and soil contamination. In terms of its impact on water and energy consumption, a comprehensive study by UCLA found that wet cleaning has only a minor impact on water use and that it uses slightly less electricity.
The toxic chemical used is “perc” and has serious consequences to both the people working with it and the wearing it in the finished garments. It also has a detrimental effect on our environment, even living close to a traditional drycleaner is not to be recommended.