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The risks of washing and stain removal in dry-cleaning

Dry-cleaning

Dry-cleaning is generally used for cleaning certain garments that

cannot be washed with water due to technical reasons related to the materials used or because they have been soiled with substances that water is not able to remove. This operation cannot be performed at home but by professional dry cleaners using specialized equipment. Besides the instructions provided on the label (type of solvent and cleaning method), it is worth remembering that dry-cleaning affects not only the fabrics of the garment but also all accessories or applications, many of which cannot withstand dry-cleaning.
For example, a woolen sweater with leather appliqués cannot be dry-cleaned, even though the wool fibre itself tolerates the process very well. A particular attention must be paid to non-fabric components such as leather trims, leather belts, buckles, buttons, pearls, or plastic rhinestones, which must be removed before dry-cleaning. If left attached, they could be severely damaged by the solvents used and the heat from the drying process.

colour discharge from leather label

damaged drawstring stopper with colour discharge

button colour discharge

plastic pearls melted by the cleaning solvent (perchloroethylene or hydrocarbon) and high temperatures

For delicate garments, it is important to remember to keep a low drying temperature in order to avoid damaging the items, even if this is not properly specified by the care symbol for drycleaning. A fundamental rule in dry-cleaning all wool or wool-blend knitwear garments with more than 40% wool (except those labelled "non-shrinkable", "super washì" or "to be washed in the washing machine") is to carry out the cleaning with reduced mechanical agitation and low drying temperature.

It is also essential to avoid adding water, ensuring that the machine drum is not damp. If the care instructions for a garment require dry-cleaning, it is advisable to follow them. Although dry-cleaning is more expensive than water washing, it is worth spending more to have a properly dry-cleaned garment, rather than risking to damage it by washing it with water.

There are different categories of solvents used in dry-cleaning with different actions:
• perchloroethylene with a milder solvent action
• hydrocarbons
• alcohols

Solvents are only capable of removing grease and oil-based dirt. When a garment contains other types of dirt, the laundries use a sort of additive to the solvent during dry-cleaning. This additive consists of a dose of water combined with detergents that will emulsify in the solvent. The additive helps remove all the dirt that is not soluble in the solvent but that can only be dissolved in water. After the dry-cleaning process the garments are being spined and successively dried, with further solvent recovery. In many cases, it is important that the airdrying temperature does not exceed 60°C, as higher temperatures can cause fabric defects, such as texture change, colour fading, etc

Dry-cleaning stages

1. Washing

The garments are placed in a densely perforated rotating drum. After the solvent is being introduced inside the drum, the drum starts to rotate alternately for 25–30 minutes (enough for achieving good cleaning results). During the washing phase, the solvent used for cleaning the garments is getting dirty and then filtered in the next stage, through special filters that purify it.

2. Solvent draining and spinning

After the washing phase, the solvent is drained out of the drum in a recovery tank, and the garments are passing through the spinning process. This helps to remove any remaining solvent and moisture excess, preparing the garments for the drying phase.

3. Drying

At this stage, the garments are getting dried with hot air that also removes any trace of remaining solvent. The hot air, introduced in the drum by a fan, contains solvent vapours that are passing through a condenser where the vapours return to a liquid state and sent for recovery.

4. Distillation

The filter only captures suspended particles and not the grease dissolved in the solvent, therefore it is necessary to "regenerate" the solvent. The solvent is sent to a distiller, where it is heated to its boiling point. The solvent vapour passes through a watercooled condenser and returns in a liquid state, becoming as pure as it was originally. In the condenser, the solvent is separated from any water that may be present.

Example

It is strictly forbidden to use a different solvent than the one indicated on the label. An illustrative example: a pair of trousers with a gold surface with the following care symbols.

The garment has been dry-cleaned with perchloroethylene that cancelled the golden effect. For obtaining the gold effect on the fabric, it has been applied a gold foil. The bond between the foil and the fabric base is more physical rather than chemical, making it highly sensitive to friction and moreover to dry- leaning. The only dry-cleaning method allowed is that with hydrocarbons performing a delicate cycle.
Dry-cleaning with perchloroethylene is significantly changing the aspect of the garment, reducing substantially the golden effect. By subjecting the original sample to dry-cleaning with hydrocarbons test and dry-cleaning with perchloroethylene test, we achieved the following results:
• no degradation after cleaning with hydrocarbons
• significant degradation after dry-cleaning with perchloroethylene

A rubbing test with perchloroethylene is completely cancelling the golden effect.
A rubbing test with hydrocarbons, on the other hand, is just slightly reducing the golden effect.

Therefore, the results indicate that the garment was dry-cleaned with perchloroethylene and not with hydrocarbons as specified on the label. In this case, cleaning the garment according to the label's instructions would not have caused the reported defect.

There are fabrics that can only be dry-cleaned with hydrocarbons and cannot be washed with water or with perchloroethylene

Water washing causes shine loss, while washing with perchloroethylene causes the disappearance of the film. Dry-cleaning with hydrocarbons does not cause any degradation of the film. Even the operation of removing the stains with solvents should be performed with maximum care

Other defects resulting from dry-cleaning

the black plastic application has deteriorated and melted

detachment of the outer film with formation of dark spots

depachment of the film due to the effect of the solvent and drying temeprature

elastomer spillage in dry-cleaning

formation of external creases due to detachment of the inner knit caused by the combined action of the solvent and drying temperature

formation of external creases due to the detachment of the internal thermo-adhesive caused by the combined action of the solvent and the drying temperature

detachment of the heat-adhesive covering the zipper due to the effect of the solvent

borders made of a film glued to a textile substrate. The solvent causes the detachment of the covering film.

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