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. The 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.
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 and that solvents also rapidly evaporate compared to water is why the process is called 'dry'..
There are two main solvents used by dry cleaners. The most popular Perchloroethylene ('Perc' for short and also known as Tetrachloroethylene) and Hydrocarbon.
Hydrocarbon replaced Fluorocarbon 113. Fluorocarbon 113 was alleged to be 'environmentally unfriendly' and is no longer imported to the UK or used by dry cleaners. Hydrocarbon is mainly used on garments such as suede's and leathers due to its softness. 'Perc' is now used by 90% of dry cleaners as it's a stronger solvent which can produce better results. 'Perc' is also far safer than the alternatives that in the past were petroleum based derivatives which were of course highly flammable. The level of perc exposure in most dry cleaners is no more than 30 ppm (parts per million). Levels of over 200 ppm for prolonged periods could result in minor headaches. All dry cleaners are frequently strictly tested and monitored.
Tagging and inspection
Tagging and inspection
When you drop off your clothes, every item is identified. Although the exact identification process may vary from dry cleaner to dry cleaner, it basically includes counting the item and describing them (e.g., shirt, trousers, suit etc.). Additional relevant information is recorded, such as requested collection dates etc. A small printed label using KD-7 ink (special ink that does not wash out with either water or solvent) is attached to each piece of clothing. The cleaner also generates a ticket and information about the order - including the customers name, address, phone number etc which is entered on a computer.
It is the cleaner's responsibility to examine the garment and point out any damage or stains to the customer prior to cleaning.
If a garment needs special attention, such as removing a stain, pressing requirements, or any relative information then there are additional coloured tags that get affixed to the particular item. Each item is then placed in the correct container depending on date of collection etc. Garments are also sorted by their colour and delicacy.
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 and remove the stain or make its
removal easier using chemicals
, by adding a water based chemical for wet stains (a stain that had water in it)
and solvent for dry stains (a stain that has grease or oil in it).
While there are many brands and makes of cleaning machines, they are all basically the same in principle and function. A dry cleaning machine is a motor driven washer/extractor/dryer that holds from 20 to 100 pounds of clothes or fabrics in a rotating, perforated stainless steel cage similar to a washing machine.
As the clothes rotate there is a constant flow of clean solvent from the pump and filter system. The solvent sprays into the clothes chamber, not only immersing the clothes, but gently dropping and pounding them against the cage wall as rotating. Solvent based soaps are also injected (depending on what fabrics are being cleaned)
As an example, a typical machine might pump perc through the clothes at a rate of 5000 litres per hour. This is more than adequate to thoroughly clean clothes.
After the frst cyce the machine spins the clothes to expel the solvent which is pumped to an oven (called 'the still') in the rear of the machine. This is then boiled at over 121 degrees and the vapours are condensed over cooling coils. The distilled solvent is then separated from any water that may have remained in the clothes or system and returned to the solvent tanks. Perc is about 75% heavier than water. Any moisture that may have condensed into water during the process, floats on top of 'perc', so therefore it is relatively simple to separate. The soil and soaps that remain in the still after distillation are pumped into a waste container and collected by a chemical waste company.
A second cycle introduces solvent and a smaller amount of soap which, after carrying out the cycle, pumps the solvent through filter disks extracting any remaining soil age and is returned to a second solvent tank.
The clothes are then rinsed with pure distilled solvent on the third cycle to remove any remaining soaps or soil.
The last cycle drains and rapidly spins the clothes to expel the solvent and then goes into 'dry cycle' by circulating warm air and again the vapours are condensed and returned to the solvent storage tanks.
Other programs (cycles) or combinations are used on the machine for garments that require delicate cleaning or may have possible colour run etc.
The dry cleaning machine is also used for other applications such as reproofing, stain resistant treatment, deodorising and flame retardant.
Post-cleaning spot removal is another part of the quality control process. Post spotting as is called, uses professional equipment and chemical preparations using 'wet' or 'dry' steam, which can be up to 320 degrees, water and vacuum. The dry cleaner will examine your clothes after cleaning is complete to see if any stains remain. A conscientious cleaner will remove the overwhelming majority of soil and stains, but there are always a percentage of very stubborn stains that may not be entirely removed for a variety of reasons. These are due to the type of stain, delicacy of material or loose dye in the garment etc.
This final phase of dry cleaning includes finishing, pressing, steaming and ironing.
Firstly steam is applied to soften the garment, then re-shaping or adding creases,
folds etc. and steam removal by either air or vacuum. All items are hand finished.
All garments have a final inspection before piecing orders together. Once complete,
all garments are covered using a heat sealing polyethylene and any other additional storage
protection such as acid free tissue paper and shoulder guards.
The original docket (of which a duplicate was issued to the customer)
is attached to the order and placed on a rail waiting collecting.
The customer returns to collect their cleaning and leaves with a smile
knowing that when wearing the garment they will look their best!
By Ashley Foord