Apparel and textiles fulfill essential functional and aesthetic needs of people. Social, psychological, physiological, physical, cultural and economic parameters are traditionally influencing apparel selection, purchasing and wearing decisions of people. As we become more aware of the impact of our activities on the environment, questions about the interface between apparel and the environment are raised and enter into the decision making process.
Apparel and textiles are soiled during normal use. Economic realities require that apparel and textiles must be cleaned and refurbished for reuse without substantially altering their functional and aesthetic properties. Consumers have the choice to clean and refurbish apparel at home or have it done in professional cleaning establishments. It is essential that available cleaning processes maintain or restore the desirable and functional attributes of the textiles. This is the joint responsibility and opportunity of the textile and apparel industry, the textile care industry and the consumer.
The Federal Trade Commission (FTC) promulgated a trade regulations rule on care labeling of textile wearing and certain piece goods in 1971 and amended it in 1983. The rule requires that apparel items have a permanent care label which provides verbal information about their regular care. The purpose of the rule is to give the consumer accurate care information to extent the useful life of garments.
The formation of the North American Free Trade Agreement (NAFTA) between the United States, Canada and Mexico provided the stimulus for using care symbols instead of language. The American Society for Testing and Materials (ASTM) has developed laundering and drycleaning symbols which the FTC is about to implement. The rule requires that manufacturers and importers of textile wearing apparel have a reasonable basis and reliable evidence in support of care instructions. Subjective and objective selection criteria are allowed.
This presentation outlines the complexity of textile care and addresses the difficulties encountered in defining reliable care instructions. Conceptual textile care spectra for non-aqueous and aqueous cleaning processes will be presented and technology options, cleaning mechanisms, textile property issues and garment damage potentials will be discussed.
At the Hamilton Environmental Summit in 1993, we redefined textile cleaning as a generic process. This redefinition dispels the paradigm that drycleaning means cleaning in perchloroethylene only. To initiate textile cleaning, we must break the soil-textile interaction forces to loosen and transport the heterogeneous soils away from the textiles. It does not matter if the medium is a liquid, a gas or even a solid. We must be able to purify and reuse the chosen medium. The soils should be concentrated for proper disposal, preferably as nonhazardous waste. But what is more important, the process must clean clothes to satisfy consumer needs, and it must be economically and environmentally feasible. Today, let us consider two practical boundary technologies: non-aqueous and aqueous cleaning:
1. Non-aqueous Textile Cleaning: There will always be a need for a non-aqueous textile cleaning technology. It is dictated by the properties of textiles and soils, but the medium does not have to be perchloroethylene only. We know that perchloroethylene is a proven medium for professional textile cleaning. Any other non-polar media, such as petroleum, carbon dioxide or other non-polar liquids, which meet the textile cleaning performance requirements, could be chosen.
2. Aqueous Textile Cleaning: At the other end of the spectrum is aqueous cleaning. We showed that the advanced professional wetcleaning technology makes it feasible to clean many textiles are traditionally cleaned in non-aqueous media. The challenge for our industry is to prove that this professional aqueous cleaning technology offers sufficient advantages to consumers so that they do not do more wetcleaning at home.
Colloid chemistry in non-aqueous and aqueous media allows satisfactory textile cleaning. The mechanism which govern polar, non-polar and particulate soil removal is reasonably understood for both media. We know that polar soils are better removed in water than in non-polar solvents and that non-polar soils are easier removed in non-aqueous solvents. Professional textile cleaners can optimize soil removal if they have access to both media.
The structure and properties of fibers, yarns, fabrics and colorants ultimately determine which cleaning process is best for them. Professional cleaners cannot change textile properties, but they must know as much as possible about them to choose the best textile cleaning process. The spectrum of textile properties dictates which cleaning process technology, non-aqueous or aqueous is best to maintain desirable textile attributes.
Based on field studies, we established preferred methods for cleaning specific garments. Tailored or structured garments and high fashion items have often linings, inter-facing, trims and other accessories or have complex design features. They behave often-differently in the same cleaning media. Damages to these items are less likely to occur in non-aqueous medium than in aqueous cleaning medium. Thus, these garments are best cleaned in a non-aqueous medium.
Many garments, such as overcoats, trousers, raincoats, parkas or sweaters may be cleaned in either media. Shirts, blankets, sleeping bags and linens are best wetcleaned. Occasionally, excessive polar or non-polar soiling dictates and overrides textile cleaning media selection criteria.A deviation from care label instructions increases the risk of garment failure. We do not recommend it, but each operator has of course the option to ignore care instruction. But if it damages garments, the cleaner will be responsible for it. The potential damage of garments during cleaning is generally higher in the aqueous medium than in the non-aqueous medium. This fact is the major reason why today drycleaning is highly utilized. Often, manufacturers low-label their garments as "Dry Clean Only" to reduce garment damage and to ensure customer satisfaction during the use of their product. I would like to discuss the more important types of garment damages that can occur:
1. Practical Shrinkage Potential
When garments shrink more than 2 or 3 percent, the garments do not fit well anymore and consumers will notice it. Shrinkage can occur during the cleaning, drying or finishing process. The new wetcleaning technology optimizes and controls the well known process parameters: time, mechanical action, heat and chemistry to reduce shrinkage. Practicing textile care specialists classify shrinkage into two categories: felting and relaxation.Felting shrinkage. This type of shrinkage is unique to wool because wool fibers have surface scales that cause differential friction effects. When wool fibers swell, as they do in water, the scales expand and are lifted. This increases differential friction between fibers and interlocks and compacts them which causes felting shrinkage. It is possible to reduce but not eliminate the felting potential of wool with process additives that lower interfiber friction and reduce fiber swelling.
Relaxation Shrinkage. During fabric and garment manufacturing, textiles are often stretched, shaped and dried under tension. This causes latent stresses at the macroscopic level (i.e., between fibers and yarns and at the microscopic level, within the fiber morphology). The macroscopic stresses are generally relaxed by mechanical action that allows movement between fibers and yarns. Microscopic stress is released by plasticization. Plasticization occurs when fibers swell in a liquid medium or when excessive energy (heat) is applied during drying. Either action lowers the cohesive energy between amorphous polymer segments and causes relaxation within the fiber matrix leading to shrinkage.
2. Theoretical Aspects of Shrinkage:
Like all processes in nature, shrinkage is governed by the potential that it can occur (thermodynamic) and by the rate at which it can occur (kinetics). These aspects are fundamental issues in polymer science and have been studied and documented extensively for natural and synthetic fibrous polymers.Thermodynamic theory predicts that there is a balance between cohesive energy and entropy when a process is at equilibrium. The cohesive energy between molecules retains the shape and dimension of a fibrous polymer solid while the entropy opens it and allows segmental relaxation that leads shrinkage. This balance establishes the fibrous shape and stability that is disturbed and temporally fixed into a non-equilibrium position during textiles and garment manufacturing.
When fibers swell in a liquid or are heated above their glass transition temperature during cleaning or drying in air, cohesive energy force weakens and entropy forces get stronger. This relaxes the morphology and fibers shrink. But because polymeric fibers are viscoelastic, the thermodynamically feasible end points are not reached instantaneously. Under these conditions, the kinetics of the process will determine the dimensional properties of fibers. Therefore, we can only delay relaxation shrinkage during textile cleaning, but we cannot stop it.
The practical consequence is that relaxation shrinkage takes time and does occur cumulatively over several cleaning cycles. All textile cleaning professionals are very familiar with the phenomenon and know it as progressive shrinkage. If we can find a cleaning and finishing process which delays perceivable relaxation shrinkage long enough to exceed a garment's life cycle, consumers will be satisfied. Non-aqueous cleaning does this readily, but it is much more difficult to manage with aqueous cleaning.
The research efforts and assessment of the feasibility of professional wetcleaning within the Research Committee RA-43 of the American Association of Textile Chemists and Colorists (AATCC) will focus on practical and fundamental principles of shrinkage. This will allow us to establish fundamental guidelines for shrinkage prediction and control.
3. Potential Appearance and Tactile Changes
Consumers purchase new textiles based on visual and tactile perception. Cleaning experts strive to retain or restore the physical properties that cause the desirable sensory attributes of textiles triggering positive purchasing decisions. This means to retain the original colors, textures and finishes during cleaning or to restore them if undesirable changes have occurred. Again, it is easier to retain these properties during non-aqueous cleaning than during aqueous cleaning.Claims that dye bleeding and staining can be prevented need to be verified. While it is possible to control selective colorant removal and staining, the diverse nature and properties of colorants and textiles suggest that it will be difficult to live up to such a broad claim. The real issue here is proper dyeing and colorfastness evaluation during textile manufacturing. Textile, apparel and manufacturers retailers and textile care specialists must work together to establish quality and test protocols that predict satisfactory cleaning performance of textiles.
Most drycleaners use fabric finishes to restore or improve the hand and feel of drycleaned fabrics. Fabric finishes for aqueous cleaning are also available to achieve the same desirable effects.