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Dry Cleaning
What Is
Dry Cleaning?
By Rachel
Ross, Live Science Contributore
Despite the name, dry cleaning is a process that uses
liquids other than water to clean clothes, bedding, upholstery and other types
of fabrics.
Water can damage certain fabrics — such as wool, leather
and silk — and a washing machine can wreak havoc on buttons, lace, sequins and
other delicate decorations. Enter dry cleaning.
Dry
cleaning chemicals
Dry
cleaners use a variety of solvents to clean fabric.
Early solvents included gasoline, kerosene, benzene,
turpentine and petroleum, which were very flammable and dangerous, according to
the State Coalition for Remediation of Drycleaners (SCRD), a group
whose members share information about cleanup programs.
The 1930s saw the development of synthetic, nonflammable solvents
— such as perchloroethylene (also known as perc or PCE) and
decamethylcyclopentasiloxane (also known as GreenEarth) — which are still used
today.
Detergents
are typically added to the solvents to aid in the removal of soils, according
to an SCRD report titled "Chemicals Used in Drycleaning Operations."
Detergents aid dry cleaning in three ways:
· Carrying moisture to aid in the
removal of water-soluble soils.
· Suspending soil after it has been
removed from the fabric so it won't be reabsorbed.
· Acting as a spotting agent to
penetrate the fabric so that the solvents will be able to remove the
stains.
Detergents
are either added into the solvent before dry cleaning begins or added into the
process at specific times.
Dry
cleaning process
Dry
cleaning machines consist of four parts, according to the Drycleaning &
Laundry Institute (DLI), an international trade association for garment
care professionals:
· The holding tank or base tank that
holds the solvent.
· A pump that circulates the solvent
through the machine.
· Filters that trap solid impurities
and soils removed from either the solvent or the fabric.
· A cylinder or wheel where the items
that are being cleaned are placed.
During
dry cleaning, the pump pulls solvent from the tank and sends it through the
filters to remove any impurities. The filtered solvent then enters the
cylinder, where it interacts with the fabrics and removes any soil. The solvent
then travels back into the holding tank so it can begin the process again.
After
the items complete the cleaning cycle, the machine goes through an extraction
cycle, which removes excess solvent.
During this process, the rotation rate of the cylinder
increases, much like the final spin cycle on a home washing machine.
After
the extraction cycle completes and the cylinder stops moving, the clothes are
either dried within the same machine (if it is a closed system) or transferred
into a separate drier.
The excess solvent is collected, filtered and transferred
back into the holding tank.
History
of dry cleaning
Dry
cleaning dates back to ancient times, according to the DLI.
Records about methods for cleaning delicate items have
been found in the ruins of Pompeii, decimated by the eruption of Mount Vesuvius
in the year 79.
In those days, many clothes were made from wool, which was
known to shrink in water.
Professional clothes cleaners, known as fullers, used
solvents such as ammonia (produced from urine) and lye, as well as a type of
clay called fuller's earth, which excelled at absorbing dirt, sweat and grease
stains.
According
to the DLI, the earliest reference to anything resembling modern dry cleaning
was a story about a clumsy maid who spilled some kerosene on a greasy
tablecloth.
The kerosene quickly evaporated, and she noticed how much
cleaner the spot where the chemical fell was.
People performed many experiments after that incident to
determine what types of solvents were best at cleaning greasy stains.
These substances included turpentine spirits, kerosene,
petroleum-based fluids, gasoline and camphor oil, according to the SCRD.
The
credit for being the first commercial dry cleaner goes to the firm of
Jolly-Belin, which opened in 1825 in Paris, according to the Handbook of
Solvents.
In Paris, of course, fashion was an important
part of society.
The clothes were soaked in vats filled with turpentine,
then put into a sort of predecessor to the washing machine and then air dried
so that the turpentine could evaporate.
The
first dry cleaner in the United States showed up around the same time. Thomas
Jennings, a U.S. tailor and inventor, as well as the first known
African-American to receive a patent in the United States, used a method called
"dry scouring" to clean clothes that traditional cleaning methods
would damage.
His process was patented in 1821, and Jennings ran a
highly successful tailoring and dry cleaning business in New York City.
The
underlying issue with petroleum-based solvents was their extreme flammability,
so alternatives were sought.
Michael Faraday, an English physicist and chemist, first
synthesized PCE in 1821.
However, it wasn't readily used in dry cleaning until the
early 1930s, after William Joseph Stoddard, a U.S. dry cleaner, further
developed PCE as a dry cleaning solvent.
Its use grew in the late 1930s and early 1940s due to a
petroleum shortage during World War II.
Environmental
and health concerns
While
it is the most popular choice for dry cleaning, perchloroethylene has been
found to be dangerous for both health and the environment. According to the
Occupational
Safety & Health Adeministration (OSHA), coming
into contact with perc puts dry cleaning employees at high risk of health
complications.
Exposure to perc vapors may occur when an employee loads
dirty clothes into a machine, removes items before the drying cycle completes,
cleans lint or button traps, changes the filters, or performs maintenance on
the machines.
Those
who have their clothes and uniforms dry cleaned regularly may also experience
the side effects of perc.
Inhaling these vapors for a prolonged period can cause
dizziness, drowsiness, loss of coordination, mild memory loss, visual
perception and blistering of the skin after prolonged contact.
People
in the dry cleaning business also face a risk of certain types of cancer.
Long-term exposure, according to the National Library of
Medicine, may lead to certain types of cancer, including esophageal, cervical,
bladder, multiple myeloma and non-Hodgkin's lymphoma.
There are also potential links to cervical and breast
cancers.
Damage
to the central nervous system, liver, kidneys and lungs may also develop.
Studies,
such as one published in 2014 in the journal Environmental Health Perspectives,
discuss links that have been found between perc and cancer, especially in the
dry cleaning business.
After going over many similar past studies, and after
studying the effects of perc on rats, the researchers in the 2014 study concluded
that perc exposure did have a strong correlation with certain types of cancer.
Similar to the EPA's 2012 classification, the 2014 study
characterized the substance as "likely to be carcinogenic to humans,"
no matter how someone came in contact with the chemical.
Another
2014 study, also appearing in Environmental Health Perspectives, specifically
examined the risk of bladder cancer in people exposed to perc.
The researchers also found strong correlations between dry
cleaners who use perc as a solvent and an increased risk of bladder cancer.
This held true even after taking into account cigarette
smoking, another known risk factor in the development of bladder cancer.
The
EPA also stated that there is some evidence, while inconclusive, that perc
affects the reproductive system in both men and women, resulting in
altered sperm structures and reduced fertility.
There has also been some research into birth defects
caused by perc, but the studies are few and have many limitations.
Perc
can be released into the air, water and soil in the environment around where it
is produced or used, including the neighborhood dry cleaner.
According to the Agency for Toxic Substances and Disease
Registry, most of the perc in the atmosphere comes from the dry cleaning
industry.
The compound breaks down very slowly in the atmosphere, so
it can travel long distances.
Perc
can enter the water system by liquid waste that may be contaminated with the
solvent.
Typically, most of the perc evaporates quickly from the
water, and the leftovers break down slowly in the water.
The chemical also breaks down slowly in soil, where it
concentrates after seeping out at waste-disposal sites.
The
future of dry cleaning
Today,
there are at least 36,000 dry cleaners in the United States alone,
according to IBISWorld, a market-research company.
However, according to several sources, including a story
published on American Drycleaner, many areas in the United States are losing dry
cleaners.
The article indicates that rising rents, casual attire
becoming the new norm, more-durable fabrics being used for clothing and cheap
clothing are just a few of the reasons for the shrinking number of dry cleaning
stores in the United States.
Another
reason is that many dry cleaners are small, family-owned businesses.
As the older generation retires, the younger generation
looks for other types of jobs. Environmental concerns are also changing the
industry.
California, for example, is phasing out the use of perc in
dry cleaning in favor of less-toxic choices, including water-based and carbon
dioxide cleaning.
Rachel Ross, Live Science Contributor
Since high school, Rachel Ross has been looking up toward
the stars to understand how the universe works. She has an undergraduate degree
from the University of California Davis and a master's degree in astronomy from
James Cook University. Rachel has spent several years making her passion for
astronomy and science education into a profession. She has even held the
position of Jedi master at an observatory. And no matter what anybody says, the
final answer is always 42 and duct tape is useful in all situations.
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