Drycleaning chemicals

We take a look at the chemicals that are among the most important for running a successful drycleaning business. The drycleaning industry has at its disposal a multitude of chemical products ranging from those designed to prevent stills foaming and boiling over, through to spotting chemicals and flame retardants. While the majority of cleaners use a range of products to improve soil removal, stain removal and quality, there are still others who perhaps use nothing more than a three-bottle spotting kit, and surprisingly there is a groundswell of cleaners who (in an effort to reduce their costs to a minimum) refuse to use detergent in their drycleaning machine.

While there may be economies to be made, machine detergent should never be one of them. It is also not uncommon to see cleaners who have a huge range of spotting chemicals from several manufacturers, most of which can be found gathering dust on a shelf or in the storeroom.

Low-cost solvent

Following the devastating effects of the pandemic, there is likely to be a lot of used solvent in the marketplace, particularly perchloroethylene, available at rock bottom prices from businesses that have not survived. We recommend that you resist the temptation. Buying used solvent can be a very costly mistake which can result in distillation problems and major corrosion issues in your drycleaning machine.

Good quality new solvent contains corrosion inhibitors and stabilisers, which control and help neutralise the acid soils released during cleaning. These are replaced when the machine is topped up with new solvent. Using old or recovered solvent in which the stabilisers will be depleted or non-existent will lead to a build-up of acidity and a high risk of corrosion in tanks and the distillation system. We strongly recommend that solvent levels in the machine are frequently topped up to the maximum level with new solvent (say once a week) to ensure that stabiliser concentrations are consistently maintained.

Machine detergent

Machine detergents, when added to drycleaning solvent, produce what is known as a synergistic effect (each enhances the properties of the other). Using detergent in the machine promotes the following:

• Removal and suspension of soil, dirt and stains, preventing greying
• Control of free moisture within the System
• Reduction of static electricity.

Some of today’s drycleaning detergents contain small amounts of water and some also contain a retexturing agent. The water assists with the removal of water-based stains, and detergents also have the ability to take into solution a certain amount of free moisture from spotting products and from the garments. Controlling water in solution in the solvent is a fundamental property of machine detergents and is critical for the safe processing of moisture-sensitive items such as animal hair fabrics. Controlled moisture in the system also helps to prevent the build-up of static electrical charges on the finished garment.

Once removed, the suspension of soil in the solvent is vital. If particulate soils are re-deposited onto fabrics, they may cause discolouration (greying) which can be very difficult or impossible to remove. Over a period of time, in normal use, the build-up of dirt and soil has a stiffening effect on fabrics, leaving some with a limp handle when this is removed in cleaning. Retexturing agents help counteract this by improving the body and handle.

It will be seen from the above that good solvent management, together with a good quality machine detergent, are highly critical factors, contributing to the overall quality of cleaning. These two chemicals are without doubt the two most important products that we use.

Spotting chemicals

Stain removal chemicals are extensively discussed in a series of LCN articles (Lets Talk Stains) which started in June 2022, so we will not repeat this here.

Anti-foam agents

During normal distillation, a layer of foam a few centimetres deep develops on top of the boiling solvent. Provided that the still is not overfilled, this layer of foam is easily accommodated in the free space above the boiling solvent. However, if the foam layer expands to fill the available free space, it will then flash up the still vapour pipe, causing what is commonly known as a ‘blackover’, accompanied by severe contamination of the water separator and distilled solvent tank. Blackovers seriously interrupt production, and usually lead to the loss of four or more hours of machine time. They result from instability in the boiling process, often caused by contamination with silicones. Serious instability can also arise from corrosion and a perforated still steam jacket, leading to free moisture, which lowers the boiling point of perc and destabilises the boiling process.

Foaming in the still can be difficult to resolve, often involving much time spent in monitoring the machine or, in the worst-case scenario, having to remove some or all of the contaminated solvent from the still. Anti-foam agents are available from suppliers, to help stabilise distillation, and in the majority of cases, these products offer a complete solution to a foaming problem. Some cleaners have to use anti-foam agents on a regular basis, if foaming is an ongoing issue.

Top tip - check your steam pressure, because excessive foaming can be a result of high steam pressure. The maximum for perc is 70psi (4.8bar).

Alkali/acid stabilisers

Typical soiling matter found on garments contains free fatty acids from body soiling, perspiration, staining, and general soiling. In some cases, these may build up in the machine ( very often because of inadequate distillation ) leading to unpleasant odours in the cleaned garments and corrosion problems in the distillation system. There are several types of product available, which can be used on a regular basis, to ensure the machine and solvent are protected against corrosion and odour problems. It is prudent to keep a product in stock in case a problem develops.

Depending on the product used, stabilisers can be in powder form, which can be added to the still after still rake-out and cleaning, or they can be added to the filter system. Liquid products are also available, for application during the cleaning cycle.

Water repellent agents

These are products designed to impart a good degree of water repellency to special classifications, such as raincoats, and to impart resistance to water-based stains. This is essential to maintain the functional properties of cotton raincoats (in particular) which may readily absorb water following drycleaning. It is important to understand that these shower-proofing agents do not waterproof fabrics. To ensure the maximum benefit from these products it is essential that that the cleaning cycle ends with a distilled rinse to remove residual detergent.

The best products of this type have to be applied by spray injection in the machine which does of course require fitting a spray injection system. At the other end of the spectrum, some cleaners simply use a silicone spray from an aerosol can following drycleaning.

Conclusion

Using your drycleaning chemicals correctly and learning how to use them effectively often enables significant improvement in drycleaning quality, which in today’s difficult marketplace can be vital in promoting higher volumes and raising turnover.

• If you have problems you would like the authors to examine please send with a good quality, high resolution (300dpi/1MB at least) pic of the item to
  kathy.bowry@laundryandcleaningnews.com

Case study

Item: this wool coat suffered serious felting shrinkage when cleaned in perc. The coat was one of several animal hair items in the same load all of which had suffered various de grees of felting shrinkage and greying, leading to some expensive claims.

Technical cause: This happened on a damp November day; the cle aner was not using machine detergent and several items in the load had been pre-spotted with water-based chemicals. In damp, wet weather textiles are likely to be carrying far more than their normal textile regain moisture. In the absence of machine detergent to absorb any excess moisture, animal hair fabrics are exposed to a high risk of felting in the presence of free water and mechanical action in the machine.

Responsibility: the responsibility here lies entirely with the cleaner. All cleaners should be using detergent in their machine and should be aware of the risk to animal hair fabrics in damp weather. They need to be hung in a warm place for at least two hours before drycleaning, to allow their moisture regains to stabilise at a low level. Leave high value items to hang overnight.