How Dry
Cleaning Works
Freshly
cleaned and pressed shirts are the hallmarks of the dry cleaning industry, but
do
you know
how the process works?
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!
Contents
Efforts to clean clothing without soap and water
go back a long time. One early pioneer was Thomas Jennings, a black freedman
who was a tailor in New York City. He wasn't satisfied with laundry methods of
the day, and in 1821 was granted a patent for a process called dry scouring,
which was advertised as being able to remove dirt and grease from clothing
while allowing garments to retain their original shape. The details of his
method, sadly, are lost to history, due to an 1836 fire that destroyed the
paperwork for scores of patents. Jennings apparently used his earnings from his
invention to support the abolitionist movement, and helped to organize the
Legal Rights Association, a group that raised court challenges to
discrimination [sources: Matchar, NIHF].
In 1855, Jean Baptiste Jolly, a French dye-works
owner, noticed that his tablecloth 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 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. After World War II, the volatile synthetic solvents carbon tetrachloride and trichlorethylene gave way to a product known
as perchlorethylene (perc), which
became the prevalent solvent choice for the industry. It was safer to handle,
but did a much better job of cleaning, required less massive equipment and
floor space, and could be utilized in retail locations offering one-hour
service.
Perc is still widely used in the dry cleaning
industry, but there's been increasing attention to its potential health risks.
Short-term inhalation exposure can result in upper-respiratory tract and eye
irritation, kidney dysfunction and neurological effects, among other health
concerns, and exposure to perc been associated with several types of cancers in
workers [source: EPA, Erickson]. EPA required dry cleaning facilities located in residential
buildings had to stop using the chemical in December 2020 [source: Burke].
California's ban on perc goes into effect in 2023 and several other states are
studying bans on the chemical as well [source: EPA].
In New York state, managers of dry cleaning
businesses are required to receive special safety training, machines that use
perc must be certified, and the businesses must document the use of perc and
other hazardous substances [source: NYC Business]. In California, concerns about perc contaminating the air led
the state to phase out its use by 2023 [source: California Air Resources
Board]. In a
March 2021 article in the journal Frontiers in Public Health, several public
health and environmental experts called for the industry to move to different
solvents, while cautioning that more evaluation of those alternatives is needed
to determine their long-term health effects as well [source: Ceballos].
تعمیر
اجاق گاز رومیزی و فردار در پونک
Do your
clothes actually stay dry after you hand them over to the dry cleaner? JUSTIN SULLIVAN/GETTY IMAGES
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.
Numbered dry cleaning
tickets keep clothes and their owners matched up from beginning to end. PORTLAND PRESS/GETTY IMAGES
When you drop off your clothes, every order is
identified. Although the exact identification process may vary from dry cleaner
to dry cleaner, it basically includes counting the items and describing them
(e.g., shirt, blouse, slacks). Also noted is the date they were dropped off and
what date they'll be ready for the customer to pick up. Then, a small, colored
tag is affixed to each piece of clothing with a safety pin or staple, and this
tag remains attached to the clothing during the entire dry-cleaning cycle. The
dry cleaner also generates an invoice, and information about the order —
including the customer's name, address and phone number — is entered into a
computer. This helps to keep track of the order.
If a garment needs special attention, such as
removing a red wine stain from a shirt or putting a double-crease in pant legs,
there's a special colored tag that gets affixed to that particular item of
clothing. Once the clothing has been washed or dry cleaned, it goes through a
quality check and the order gets re-assembled. This means the clothing is
bundled together for the customer to pick up. Remember, every order is
identified by a colored tag with a number on it so the person who re-assembles
the order knows which shirts and which slacks go together and to whom they
belong.
Though recommendations vary, some dry cleaning
websites advise that it's not necessary to treat stains prior to taking
garments to the dry cleaner, and some dry cleaner websites caution against it,
because there's a risk that you may actually make stains hard for the dry
cleaner to remove. Cleaners have a variety of fluids that they can use to
remove stains from fabric, which act in a different way than the water that you
might use. However, it's important to alert your cleaner to everything that
you've spilled on the clothing, because the residue from those substances can
cause trouble during dry cleaning and worsen the damage to your clothing
[source: Captain Dry Clean].
If you don't know what to do when a stain
happens, call your cleaner and ask him or her what to apply.
Despite the name, the clothes don't stay dry
during dry cleaning. They actually get wet! While there are many brands and
makes of cleaning machines, they are all basically the same in principle 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
solvent through the clothes at a rate of perhaps 1,500 gallons (5,678 liters)
per hour. The most commonly used solvent is perchloroethylene, known in the
industry as "perc." Perc is about 69 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, condensed over cooling coils, and then passed through a secondary air
control to get the solvent out
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.
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.
Post-cleaning spot removal is another part of
the quality control process. Post-spotting, as it is called, uses professional
equipment and chemical preparations using steam, water, air, and vacuum.
Post-spotting involves a fairly simple process for removing a stain. If the
stain had water in it to begin with (bean soup, for example), then it takes
water or wet-side chemicals to remove the stain. If the stain was on the dry
side (grease, oil-based paint, tar, nail polish), it takes solvents or dry-side
chemicals to remove the stain.
In home laundry, most wet-type stains come out
during the washing process. Grease does not. The opposite is true in dry
cleaning — it will leave the wet-side stains intact after the cleaning cycle.
On the other hand, the solvent removes grease and oils during the cleaning
cycle. The exception to this rule involves incorporating a "charge"
of specially formulated dry-cleaning soap (an anhydrous emulsifier)
into the cleaning cycle.
The dry cleaner will examine your clothes after
cleaning is complete to see if any stains remain. If they do, post-spotting
tries to get them out. A conscientious cleaner will remove the overwhelming
majority of soil and stains, but there is always a small percent of very
stubborn stains that may not be entirely removed for a variety of reasons, such
as:
- Tannin stains set by heat and time
- Original dye stripped or faded
- Bleached-out spots or sun-faded materials
- Foreign dye deposit
A worker
uses a pressing machine to press shirts in the finishing stages of the dry
cleaning process. JUSTIN SULLIVAN/GETTY IMAGES
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
The pressure comes from the head of the pressing
machine, while steam is diffused through the bottom. Most machines not only emit
steam, but can vacuum it out as well!
The demand for environmentally safe products
has increased in recent years as a result of government regulations and greater
consumer awareness of environmental issues.
As a replacement for perc, alternative solvents
have been developed, including ones that utilize silicone and chemicals from
corn, as well as hydrocarbon-based solvents [sources: NY.gov, Coons, Leverette].
The EPA and organizations such as the Toxics Use
Reduction Institute at the University of Massachusetts Lowell have encouraged
dry cleaners to move to a process called professional wet cleaning, which uses
water and biodegradable detergents in computer-controlled machines. Garments
are then finished with tensioning and pressing equipment [sources: Onasch,Turi.org, EPA]. According to the
institute, some cleaners who've switched to wet cleaning have reported savings
in energy costs and water use as well [source: Turi.org] In Washington state, King
County, where Seattle is located, has offered grants to dry cleaners to cover a
portion of the estimated $40,000 to $60,000 cost of switching to wet cleaning
[source: O'Neill].
While some in the industry have been skeptical
about whether wet cleaning works as well as conventional dry cleaning,
proponents say that advances in wet cleaning systems can handle most fabrics
[source: Hay].
Originally Published: Apr 1, 2000
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