Part 1: Friend or foe?12 April 2022
In the first of a two-part report, Brian Pearce make sense of the many solvents available to drycleaners and whether they actually deserve the hype given to some and the demonisation of others, notably Perc
When I first joined the industry, the range of fabrics was limited and consisted of cotton, linen, wool and silk, plus a small amount of the new fibres such as nylon and acetate rayon. The solvents we used were white spirit and Perchloroethylene (Perc). Trichloroethylene had been phased out as it damaged acetate rayon and white spirit was on the verge of being phased out to be replaced with Hydrocarbon. Oddly, during the transition from white spirit to Perc customers would complain that their garments had not been drycleaned as there was no residual odour on their clothes.
Sixty years later, there have been significant changes. How we clean and process our customers garments has always been dictated by the demands of the fashion industry and their use of newly introduced synthetic fibres coupled with their mixtures into fabrics. Polyurethane, PVC, and Elastane/Spandex are not always compatible with some drycleaning solvents, in particular Perc. Particularly problematic are the adornments that designers add to garments without any consideration of how safe they will be to withstand the cleaning process, the number of claims against drycleaners due to incorrect information on care labels emphasises the problem.
For some years, it has been perceived that Perc, like fluorocarbon would be discontinued as it has been deemed a hazardous substance due to suspected links to a danger to marine life, soil and water contamination and as a potential risk of cancer to operators in the industry.
Several alternative new solvents have been developed and introduced namely, Green Earth, Hydrocarbon, K4, Sensene and Hi-Glow all of which require a multi-solvent machine which uses a vacuum for distillation and drying. Wetcleaning, an aqueous process, has also become a major force in garment care.
However, Perc is the still the solvent of choice for most drycleaners. It has been risk assessed under the existing chemicals regime in 2007 and from 2010 under the European legislation on the safe and environmental use of chemicals, called REACH. Numerous epidemiological studies – these study very large numbers of people – in recent years have shown that Perc solvent is safe in drycleaning when properly used in accordance with new regulations and directives.
Perc showed no clear association between its exposure and subsequent cancer morbidity in approximately 10,000 workers in drycleaning and laundry over more than 20 years in a recent study in Sweden. Perc is recognised as a hazardous substance and possibly a carcinogen, but workers’ exposure today to perchloroethylene is much better controlled due to the introduction of closed machine technology and, in the UK, the Solvent Emissions Directive which empowers local Councils to monitor the solvent use, maintenance, and good practice of drycleaners within their borders.
Is Perc banned anywhere? The US (California), France and Denmark are often taken as an examplars of this. The truth is that out of the more than 50 states in the US, California is the only state to have prohibited the use of perc drycleaning machines from 2023 onwards, due to major cases of soil remediation.
However, California has now started as well to look more critically at the alternative solvents and offering $10,000 to drycleaners that switched to alternative system and in particular wetcleaning, environmentalists urged the board to ban the most common alternative to Perc which is Hydrocarbon, critics said it could lead to ozone pollution.
Among the EU countries, a majority have implemented stringent requirements for the use of perchloroethylene in dry-cleaning. No EU country has banned perc for use in drycleaning, as a proper enforcement of existing regulations is seen as sufficient to ensure safe handling and protection of workers and the general public around drycleaning shops. Also, Denmark implemented measures, which are often mentioned as a ban on perchloroethylene, while it moreover implements strict measures for all solvents used in drycleaning. Two thirds of Danish drycleaners are using perchloroethylene according to the Danish Dry-Cleaning Association.
In many EU countries, drycleaning machines older than 15 years are typically prohibited; only 5th generation machines are allowed. However, fourth generation machines may be used if best practices (e.g., good housekeeping, optimal machine operation, and recycling) are implemented and they meet EU emission requirements.
The US EPA’s National Emission Standards for Hazardous Air Pollutants (NESHAPS) regulations stipulate that 2nd generation machines must be upgraded to 4th generation, and 3rd generation machines must be retrofitted or upgraded to 4th generation machines; only 4th generation and later machines can be sold, leased, or installed.
In France there are stringent restrictions on the use or Perchloroethylene. Existing machines that do not bear the French NF quality certificate were banned in 2018. Those with the label will need to be removed by 2022 unless they are a safe distance from local residents.
¦ Perchloroethylene: At a KB value of 90 it is currently the second strongest solvent available after Sensene, it has the shortest process times, plus it has the widest range of additives in terms of detergents and after treatments. However, it is an aggressive solvent when it comes to buttons, trimmings, and fabrics such as Polyurethane, PVC, and Elastane/Spandex, this however can be counterbalanced by its ability to dry at low temperatures making it a safer solvent for heat sensitive fabrics and fibres.
¦ Hydrocarbon: has a lower solvency power, therefore oil based stains will require more pre-treatment, however it is a gentler solvent making it kinder to more delicate fabrics such as silk, because it does not remove the yarn oils and coatings. It is also less likely to dissolve buttons and damage sensitive fabrics. Expect longer drying time and take care when drying heat sensitive fibres.
¦ Green Earth: Has the lowest solvency power of all the solvents, which makes the cleaning of beaded garments much safer, but the removal of oil based staining and ingrained soiling more difficult and will require additional attention and treatment prior to dry cleaning if satisfactory results are to be achieved. Excellent results can be achieved on suede and leather garments in Green Earth but again ingrained soiling and oil based soiling will need detailed and special attention during pre-spotting. Because of the low solvency power of the solvent, it does not remove the natural oils in the skins so little or no oil needs to be added during the cleaning process.
¦ K4, Dibutoxymethane: is an oligoether (more than one -O- grouping) or acetal containing two butyl groups and a methylene grouping. It is used in cosmetics, as a cleansing agent, or solvent. It can be classed as a green solvent, as it contains no halogens, and is not very toxic. With a solvency power of 75°C it is an effective oil and grease remover and leaves a soft handle to the garments after cleaning.
¦ HiGlo: Is a Hydrocarbon to which Glycol Ether has been added, this combination has increased the capacity of the solvent to absorb water enabling more effective pre-spotting with water based chemicals and increased the solvency power to 45 which more of an effective grease and oil based stain remover that Hydrocarbon alone.
¦ Sensene: is a combination of Hydrocarbon and modified alcohol, it has the highest solvency power of all the solvents and will remove oil stains from polyester fabric, however despite the high KB value of 161 it appears to be as safe if not safer than the other Hydrocarbon based solvents and does not damage plastic buttons or trimmings. It has a high water absorbency which makes it safer when water based pre-spotting agents are used and on days of high humidity when damp garments can shrink as a result of the cleaning process. The solvent also has a soft feel after processing which assist the pressers when finishing the garments.
It is an important factor with multi-solvent machines to take into consideration are odours caused by microbial growth in the water separators, this is unlikely with the non-flammable solvents, but a routine of cleaning and treatment is essential with Green Earth and Hydrocarbon machines
It is a concern regarding care labels for the dry cleaners who use alternative solvents, to date I am not aware of any testing on garments to establish if they qualify to be included in the same category as the ? symbol. Unfortunately, until these tests are proven, technically if there is a problem with the cleaning of a garment the drycleaner could be held responsible for not cleaning in accordance with solvent noted on the care label.
In the June UK edition Bryan Pearce investigates wetcleaning chemicals and detergents.