Effective maintenance of firefighter’s uniforms5 September 2018
Richard Neale of LCT Worldwide explores the most efficient methods to effectively remove soot and other carcinogens and other contaminants from firefighters uniforms
A recent newspaper article in The Sunday Times* last month highlighted the apparent high incidence of cancer among firefighters up to the age of 75, which was attributed to carcinogens from fires left in the textiles after cleaning. This month, following a report in May LCNi,** we look at ways in which the launderer or garment rental operator can minimise those risks which might be affected by inadequate cleansing, before re-use of protective garments worn by firefighters.
Firefighters’ kit can be effectively cleansed to the required very high standard by routine application of the best principles of professional textile cleansing, but this does require knowledge of the correct techniques and chemistry to address the different soiling and staining types which are picked up by the modern firefighter.
A professionally cleansed garment should be free of particulates and fibrous matter, with particular reference to carbon particles and the occasional asbestos fibre. It should be free from the proteins found in sweat, blood and many foodstuffs. There should be no trace of any vegetable dyes or other stains and the garment will smell sweet and fresh to the human nose.
It is now possible to rate a firefighters’ laundry with a simple technical audit, to assess processes for adequacy and to monitor the laundered results for acceptability and safety. This month we pinpoint the knowledge, systems and equipment to reach the required standard, to demonstrate and justify that the essential duty of care has been discharged.
Types of contamination to be removed
Particulate and fibrous matter gets onto all parts of modern fire-wear. This includes very fine carbon particles from smoke and soot, mixed in with all types of short fibres from damaged insulation (including glass fibre and even asbestos). These all require enhanced chemistry in the detergent system to wrap around every individual particle and fibre, to lift these off the fabric and to suspend them in the wash liquor until they can be flushed to drain. The group of chemical compounds needed are referred to as suspending agents, the most common of which is carboxy-methyl-cellulose (CMC). Most leading commercial detergent suppliers have premium products with the correct degree of suspending power for this critical duty.
Proteinic soiling includes blood and perspiration and many types of foodstuffs (including milk and butter). This needs conditions in the pre-wash to soften each type of protein, followed by an alkaline main wash at higher temperature (to open out any cotton yarns and mechanically release the soiling).
Oily soiling and staining needs chemistry to help to emulsify the different oils (both mineral and vegetable) and fats (including the food fats in butter and margarine). The emulsifiers needed for firefighters’ staining must cover a broad range of HLB (hydrophilic-lipophilic balance) ratios, to cater for the different chemical characteristics of spa oils, food fats, mineral oils and engineering greases. The more common high-range emulsifiers will not perform adequately on food fats and spa oils.
Vegetable dyes from tannin and other colourings, found in blackcurrant, beetroot and orange juices, for example, require chemical oxidation to de-colour them.
Basic wash processes for successful removal of most contamination
If there is a heavy load of loose debris on the uniform, it is usually best to get rid of this in an initial sluice stage, with a high water-level (a dip of 250 – 375mm in a 100kg washer extractor), which runs for 3 – 4 minutes before a 1-minute drain. If in doubt, it’s usually advisable to include the sluice stage rather than risk omitting it.
The pre-wash operates with a medium water level (a dip of 125mm in a 100kg machine) to assist in the final removal of any loose lint and minor debris.
Addition of one third of the detergent mix will assist with this and with wetting out the main protein stains. These require softening for 4 – 5 minutes in the pre-wash to ensure complete and easy removal in the main wash and this essential softening is best carried out at around 38C – any lower and the stage time may need to be increased, any higher and the risk of ‘cooking’ the stains onto the fabric rises markedly, making protein stains impossible to wash off in the next stage.
The main wash should run for 10 – 15 minutes at a temperature sufficient to remove the softened proteins. This should be at a temperature sufficient to achieve implied thermal disinfection (71C for cotton, 65C for polyester and nylon maintained for a minimum of three minutes plus mixing time), unless chemical disinfection is being employed. The water level should be at the low setting (meaning 75mm in a 100kg machine).
The emulsifier addition to improve removal of fatty or oily soiling should be to the pre-wash, because this should cling to the textiles and be carried forward to work also in the main wash.
The wash process should conclude with three rinses rather than two rinses with inter-spin, to minimise the risk of soiling being forced back into the clean fabrics during the inter-spin. More emulsifier will be needed if any of the garment components include nylon or polyester fibres, because these are oleophilic - they attract and hold the fats and oils in the contamination onto the fibre surface. Emulsifier costs can be minimised by choosing the correct emulsifier, appropriate to the type of fat or oil on the garments. For example, a fire in a spa oil factory will call for an HLB value that covers the range HLB7 to HLB9, to pull off the highly refined essential oils successfully. Oxidation of vegetable dyes on fire-wear is often best achieved in the main wash using either liquid hydrogen peroxide or a powder compound designed to generate this in the wash.
Many garment assemblies are unable to withstand the temperatures needed for implied thermal disinfection, but they can usually be disinfected chemically. There are modern disinfectant additives now coming to market which are much more powerful and some of these are substantive, that is they bond to the textile to give a degree of continuing protection against infections. If the garments are able to withstand implied thermal disinfection, then the higher temperatures employed usually improve the speed of soil and stain removal and of oil emulsification.
It is not reasonable to expect fire and rescue workers to put on ‘clean’ kit which is smelly, and which is demonstrably not clean, when they set off to tackle an incident. This month we have looked at the key features to build into a professional cleansing process which should ensure that this never happens. The washing machine itself is not critical – any fully programmable washer extractor with an inverter drive should be capable of doing the job. The skill comes in the programming and in selecting the correct chemistry:
to deal with removal of soot and the occasional asbestos fibre;
to emulsify oils, fats and greases; and
to de-colour vegetable dye stains.
You will need help with this from your chemicals supplier, to get the best out of their particular products and formulations for fire-wear. It is also wise to consider the advantages of regular (annual) monitoring of your systems and performance, so that in the event of an infection or injury that can be tracked back to incorrect cleansing, there is an independent assessment report available to demonstrate that your essential duty of care has been discharged.
It is possible to assess the residual level of bacterial contamination on a washed fabric, using inexpensive dip-slides, which give an indication which is quite adequate for this purpose. The power of the wash process with respect to removal of proteinic soiling or vegetable dye staining can be gauged using calibrated, pre-stained EMPA swatches. The power of the process, with respect to re-deposition of particulate and fibrous matter, is more difficult to measure, but can be achieved with a multi-wash swatch and a laundry reflectometer. The use of these tools is well-merited where fire-wear is concerned.
* Sunday Times, 25 February 2018
**See Protection through decontamination, LCNi, May 2018, page 20-22.