Dry cleaning

DRY CLEANING

Doing laundry has been a common household activity for years. Whether the techn­ology­ was­ beating the garments on rocks by the river or pushing buttons on programmed washing machines, this process depends on water and a mechanical action usua­lly assisted by soap or an alkali. The purpose of an alkali is to saponify the oils and dislodge ordinary soil and other matter. More often­ than not, the soapy agent holds soil in suspension as it becomes loose during the wash cycle, and is subsequently flushed away during the rinse cycle and centrifugal spin.

The drying process for doing laundry at home is either hanging clothes on a clothesline or tumbling them in a gas- or electric-heated dryer.

Dry cleaning, on the other hand, is different. It's a process that cleans clothes without water. The cleaning fluid that is used is a liquid, and all garments are immersed and cleaned in a liquid solvent -- the fact that there is no water is why the process is called "dry." In this article, we will take a behind-the-scenes look at the dry-cleaning process so that you can understand what happens to your clothes after you drop them off at the cleaners!

DRY CLEANING EVOLUTION

Like many inventions, dry cleaning came about by accident. In 1855, Jean Baptiste Jolly, a French dye-works owner, noticed that his table cloth became cleaner after his maid accidentally overturned a kerosene lamp on it. Operating through his dye-works company, Jolly offered a new service and called it "dry cleaning."

Early dry cleaners used a variety of solvents -- including gasoline and kerosene -- to clean clothes and fabrics. In the United States, the dry-cleaning industry is fairly new and has developed only during the past 75 years. Since World War II ended, the volatile synthetic solvents carbon tetrachloride and trichlorethylene gave way to a product known as perchlorethylene (perc), which became the overwhelming solvent choice for the industry. It was not only safer and faster, but did a much better job of cleaning, required less massive equipment, less floor space, and could be installed in retail locations offering excellent quality one-hour service.

As a result of this innovation, the majority of clothes today are cleaned by perc. A proliferation of cleaning franchises and dry-cleaning businesses offering fast service from convenient, clean, and attractive locations evolved to change the industry into what we see today.

THE PROCESS

When you drop your clothes off at the cleaners, the employees follow a pattern that holds true at just about any dry-cleaning operation running today. Your clothes go through the following steps:

  • Tagging and inspection - Some method, whether it is small paper tags or little labels written on a shirt collar, is used to identify your clothes so they don't get mixed up with everyone else's. Clothes are also examined for missing buttons, tears, etc. that the dry cleaner might get blamed for otherwise.
  • Pre-treatment - The cleaner looks for stains on your clothes and treats them to make removal easier and more complete.
  • Dry cleaning - The clothes are put in a machine and cleaned with a solvent.
  • Post-spotting - Any lingering stains are removed.
  • Finishing - This includes pressing, folding, packaging and other finishing touches.

PRE-TREATING STAINS

Pre-treating stains is similar to the procedure used at home when you apply a stain remover to stains prior to washing them. The idea is to try to remove the stain or make its removal easier using chemicals. You can even help the process, especially if you catch the stain early! Simply apply water for wet stains (a stain that had water in it) and solvent for dry stains (a stain that has grease or oil in it). Then, gently tap and blot both sides of the fabric with a soft cloth so the stain "bleeds off" onto the cloth. Then, rinse the fabric, let it dry and your cleaner will do the rest.

If you don't know what to do when a stain happens, call your cleaner and ask him or her what to apply.

Dry Cleaning

While there are many brands and makes of cleaning machines, they are all basically the same in dry cleaning machineprinciple and function. A cleaning machine is a motor-driven washer/extractor/dryer that holds from 20 to 100 pounds (9 to 45 kg) of clothes or fabrics in a rotating, perforated stainless-steel basket. The basket is mounted in a housing that includes motors, pumps, filters, still, recovery coils, storage tanks, fans, and a control panel. In all modern equipment, the washer and the dryer are in the same machine. Doing this makes it possible to recover nearly all of the perc used during cleaning, which is better for the environment and saves the dry cleaner money.

As the clothes rotate in the perforated basket, there is a constant flow of clean solvent from the pump and filter system. The solvent sprays into the basket and chamber constantly -- not only immersing the clothes, but gently dropping and pounding them against baffles in the cylinder as well. The dirty solvent is pumped continuously through the filter and re-circulated free and clear of dirt that gets trapped in the filter.

As an example, a typical machine might pump perc through the clothes at a rate of perhaps 1,500 gallons (5,678 liters) per hour. Perc is about 75 percent heavier than water. If a cycle lasts for eight minutes, the clothes would be doused during mechanical action with 200 gallons (757 liters) of solvent. This is more than adequate to thoroughly clean the clothes.

The next cycle drains and rapidly spins the clothes to expel the solvent and then goes into a dry cycle by circulating warm air through the clothes. The remaining fumes and solvent are vaporized by warm air and then condensed over cooling coils. The distilled solvent is separated from any water (that may have remained in the clothes or system) and returned to the tank as distilled solvent. Since any moisture that may have condensed into water during the process floats on top of perc, it is relatively simple to separate it.

Cleaning plants using petroleum solvent rather than perc are exposed to a different set of circumstances and face some challenging considerations. The solvent is flammable, and therefore many fire-prevention steps must be taken for safety. The solvent is very slightly lighter than water and the two mix easily. There is also a need for higher temperatures to dry and deodorize the garments, which makes shrinkage and re-deposition of soil into the clothes more likely. These disadvantages are the reason why the industry currently uses perc almost exclusively.

Regardless of which solvent the dry cleaner uses, the quality of cleaning, the degree of soil removal, the color brightness, the freshness, the odor and the softness all depend on the degree to which the cleaner controls his filter and solvent condition and moisture. Quality control can vary day to day unless the cleaner is constantly attentive to these factors.

FINISHING

The final phase of dry-cleaning operations includes finishing, pressing, steaming, ironing, and making any necessary repairs to restore the garment. This is the least mysterious process since most dry-cleaning stores have their professional finishing equipment in plain view of customers.

Once the clothes are cleaned, they are pressed or "finished." The steps in this process include:

  • Applying steam to soften the garment
  • Re-shaping it through quick drying
  • Removing the steam with air or vacuum
  • Applying pressure to the garment