How Dry Cleaning Works?
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
1. 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.
2. Pre-treatment - The cleaner looks for stains on your clothes and treats them to
make removal easier and more complete.
3. Dry cleaning - The clothes are put in a machine and cleaned with a solvent.
4. Post-spotting - Any lingering stains are removed.
5. Finishing - This includes pressing, folding, packaging and other finishing touches.
The following sections look at each of these steps in detail.
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.
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 them what to
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 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.
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-base 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
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
• 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!