Dry cleaning of clothes

Dry cleaning is a specialised process for cleaning garments and textiles using non-aqueous chemical solvents instead of water. It effectively removes oil-based stains, dirt, and odours from fabrics that might shrink, distort, or lose colour when washed with water. The process is widely used for delicate materials such as silk, wool, and certain synthetic fibres, which require gentle handling and precise cleaning methods.

Background and History

The origins of dry cleaning date back to the early nineteenth century. In 1821, Thomas Jennings, an African-American tailor in New York, patented a method of “dry scouring” clothes using non-water-based cleaning agents. Later, in 1855, French dye-worker Jean Baptiste Jolly discovered that kerosene and other petroleum-based solvents could remove stains without damaging fabrics — a process that became known as “French cleaning.”
Early dry-cleaning solvents were highly flammable, posing serious safety hazards. By the early twentieth century, safer alternatives such as chlorinated hydrocarbons were developed, leading to the widespread adoption of modern dry-cleaning practices. Over time, environmental and health concerns led to the introduction of newer, eco-friendlier solvents and improved waste management systems.

Principle of Dry Cleaning

The fundamental principle behind dry cleaning is the use of a chemical solvent instead of water to dissolve and remove stains. Most dirt and grease stains are hydrophobic, meaning they do not dissolve in water but can be broken down by organic solvents. The process relies on both the solvent’s chemical properties and mechanical agitation to lift and extract contaminants from fabric surfaces.
The solvent penetrates the fabric fibres, loosens the soil particles, and then carries them away during the cleaning and filtration cycle. The clothes are subsequently dried in controlled conditions to remove residual solvent before pressing and finishing.

Steps in the Dry-Cleaning Process

The dry-cleaning process generally involves several well-defined stages:

1. Inspection and Tagging: Each garment is carefully examined for stains, damage, and fabric type. Identification tags are attached to track items throughout the process.
2. Pre-treatment: Specific stains such as grease, ink, or wine are treated manually with chemical spot removers before the general cleaning process begins.
3. Cleaning: The garments are loaded into a dry-cleaning machine, resembling a large front-loading washing machine. Instead of water, it uses a cleaning solvent — most commonly perchloroethylene (PCE) or alternative eco-solvents. The clothes are gently agitated to allow the solvent to penetrate and dissolve the dirt.
4. Extraction: After cleaning, the solvent is extracted from the garments through spinning. The used solvent passes through a filtration system to remove impurities and is often recycled for reuse.
5. Drying: The clothes are dried in the same machine using warm air circulation, which evaporates any remaining solvent. The vapour is condensed and recovered for future use.
6. Finishing: Once dry, garments are pressed, steamed, or ironed to restore their original appearance. They are then inspected for any remaining stains and packaged for return to customers.

Common Solvents Used in Dry Cleaning

Over the years, several solvents have been used, each with distinct properties:

• Perchloroethylene (PCE or “Perc”): The most widely used solvent due to its high cleaning efficiency and non-flammability. However, it poses environmental and health risks if not properly handled.
• Hydrocarbon Solvents: Derived from petroleum, these are less aggressive and more environmentally friendly alternatives to PCE. They are slower to dry but safer for delicate fabrics.
• Liquid Carbon Dioxide (CO₂): Used in advanced systems, CO₂ is non-toxic, non-flammable, and environmentally sustainable.
• Silicone-based Solvents (D5): Provide excellent cleaning for delicate garments with a soft finish and minimal environmental impact.

Advantages of Dry Cleaning

Dry cleaning offers several benefits over conventional water-based washing:

• Preservation of Fabric Quality: Prevents shrinkage, distortion, and colour bleeding in delicate fabrics.
• Effective Stain Removal: Removes oil-based stains and grease that water cannot dissolve.
• Convenience: Reduces the need for extensive ironing and finishing, keeping garments crisp and smooth.
• Longevity of Clothes: Minimises wear and tear, extending the life of expensive or delicate garments.
• Odour Elimination: Effectively removes musty smells and residual odours.

Disadvantages and Concerns

Despite its effectiveness, dry cleaning has several limitations and potential drawbacks:

• Chemical Exposure: Prolonged contact with solvents such as PCE can pose health risks to workers and the environment.
• Environmental Impact: Improper disposal of solvents can contaminate soil and groundwater.
• Cost: Dry cleaning is more expensive than regular laundering due to specialised equipment and solvent use.
• Limited Stain Types: Water-soluble stains, such as those from coffee or perspiration, may not be fully removed.
• Energy Use: The drying and solvent recovery stages consume considerable energy.

Environmental and Technological Developments

In response to environmental concerns, the dry-cleaning industry has introduced safer and more sustainable alternatives. Modern cleaning systems feature closed-loop machines, which capture and recycle nearly all solvent vapours, reducing emissions.
Newer technologies such as wet cleaning — using specialised biodegradable detergents and computer-controlled washing — are emerging as eco-friendly substitutes for traditional solvent-based methods. These systems use minimal water and produce no hazardous waste.
Governments and environmental agencies worldwide have implemented strict regulations to phase out harmful chemicals like PCE and encourage the adoption of greener solvents and energy-efficient technologies.

Significance in Modern Textile Care

Dry cleaning remains essential in maintaining high-quality textiles, especially for garments made from wool, silk, rayon, and tailored fabrics. It supports industries ranging from fashion and hospitality to uniforms and theatre costume management. The precision and care involved make it an indispensable service in modern textile maintenance.