Disinfection in professional textile care

1. Introduction

From early 2020 on, the world is being kept prisoner by the global Covid-pandemic. As a result, the interest of customers of the retail textile care industry in the hygienic quality of professionally cleaned textiles is growing. This document will supply information on hygienic cleaning and disinfection of textiles in relation to laundry and textile care processes.

2. What is disinfective cleaning?

The first step is the definition of disinfective cleaning. There are two ways of defining disinfective or hygienic processes. The first definition focusses on the hygiene demands for the final product and the second one focusses on hygiene performance of the process itself.

2.1 Hygienic demands for cleaned textile products

The demands for a hygienic clean product are based upon the number of bacteria, which can be found at the textile surfaces after cleaning. Worldwide, only demands are set for the limited presence of bacteria, up till now not for viruses, as for example Covid. The number of bacteria is expressed in cfu per surface area, which stands for Colony Forming Unit. The bacterial disinfection is measured using a RODAC-plate. This a plate with a bacterial growing medium, which is pressed at the textile surface. Then the plate incubated at 37°C and the bacteria grow out to colonies, which are visible and can be counted (see figure 1). Every spot in this figure represents a bacterial colony.

Figure 1) Example of bacterial colonies on a RODAC-plate after incubation.
Figure 1) Example of bacterial colonies on a RODAC-plate after incubation.

In table 1, as an example some national hygienic demands related to the presence of bacteria are presented. In some countries a discrimination is made between pathogenic and non-pathogenic bacteria., e.g., Belgium and the Netherlands.

Table 1) Examples of demands for hygienic textile products
Table 1) Examples of demands for hygienic textile products

2.2 Hygienic cleaning process

A hygienically cleaning process is a cleaning process that guarantees that the laundry cleaned according to this process meets with the hygienical demands as stated above in 2.1. Another much used definition is a lethality or log reduction of at least log6. What does that mean? A log reduction of 6 means that 999.999 out of 1.000.000 million bacteria are deactivated in the cleaning process! Again, this demand is focussed on bacteria and not on the deactivation of viruses. The log-reduction of bacteria in a laundry process can relative simply be measured by using a DES-controller

The German Robert Koch Institute additionally has formulated demands for hygienically virucidal processes, which is tested in a laboratory set-up (EN14476). This standard has 2 level for virucidal activity of a laundry process:

  1. Limited virucidal, minimum log 4 reduction for enveloped viruses (as Covis-10) only
  2. Virucidal, minimum log 4 reduction for enveloped and non-enveloped viruses

This testing method is very complex and cannot be performed outside dedicated and sophisticated laboratories.

3 Disinfective cleaning processes

In textile cleaning and laundry, 3 types of cleaning processes are applied, depending on textile type:

  • Laundry
  • Professional wet cleaning
  • Dry cleaning

The choice for a washing/cleaning process depends on the type of textile to be cleaned and equipment installed. If possible, for most common textile products as e.g., cotton, polyester and their blends, a laundry process is applied. Sensitive textiles, e.g., wool or silk, are sensitive to textile damage by a standard laundry process. A professional wet cleaning or dry-cleaning process should be applied for these materials to prevent damage. The textile care label provides information on the cleaning processes allowed for an individual piece of garment. Table 2 provides an overview of the textile care process selection for standard and sensitive textiles

Table 2) Overview textile care processes for standard and sensitive textiles
Table 2) Overview textile care processes for standard and sensitive textiles

3.1 Disinfection in laundry processes

The demands for a hygienic clean product and cleaning process have been defined in paragraph 2, the next step is to define laundry and cleaning process conditions. The COVID 19 virus can be deactivated in laundry processes – like most other enveloped viruses – by thermal disinfection or by chemo-thermal disinfection. The classical option for disinfection is thermal disinfection, meaning that within a laundry process a required temperature is maintained for minimum amount of time. The demands are country specific as shown in table 3. As can be seen from the table, those demands can differ significantly from country to country.

Table 3) Country specific demands for hygienic laundry processes
Table 3) Country specific demands for hygienic laundry processes

The WHO guideline for COVID demands a process of 25 minutes at 70˚ C. Of course, not all textile products can be treated in that type of disinfection processes. Sensitive textiles will be damaged by this type of disinfection at elevated temperatures. The solution here is to add a disinfective agent in combination with lower temperatures, this is called chemo-thermal disinfection. A commonly used disinfective agent in the laundry industry is peracetic acid.
Process parameters of chemo-thermal disinfection processes as supplied by suppliers or following applicable legislation have to be exactly followed to ensure a proper result:

  • Time and temperature
  • The defined temperature to be present during the full main wash time
  • Concentration of the detergent and disinfective agent
  • Bath levels

Not meeting with these prescribed parameters can result in an insufficient level of disinfection. Proper documentation, validation and monitoring of process and product quality are required to enable a guaranteed level of hygiene.

3.2 Disinfection in professional wet cleaning

The remarks made for a hygienical laundry process, also hold for Professional Wet Cleaning. Thermal disinfection is however not possible for this type of process, as this no doubt will damage the sensitive textiles for which this process is meant. Disinfection is therefore only possible by using disinfecting agents at the low temperatures which are characteristic for the professional wet cleaning process. Please be aware, that some disinfective agents can damage the sensitive textiles to be cleaned.
Process parameters of chemo-thermal disinfection processes as supplied by suppliers or following applicable legislation have to be exactly followed to ensure a proper result:

  • Time and temperature
  • The defined temperature to be present during the full main wash time
  • Concentration of the detergent and disinfective agent
  • Bath levels

Not meeting with these prescribed parameters can result in an insufficient level of disinfection. Proper documentation, validation and monitoring of process and product quality are required to enable a guaranteed level of hygiene

3.3 Disinfection in dry cleaning

Disinfection is dry cleaning is different, as in dry cleaning solvents are used instead of water as the cleaning liquid. First important aspect is that the standard dry-cleaning process, e.g., in PERC or HCS, is not a hygienic cleaning process and does not disinfect the cleaned garments to the levels as described in paragraph 2. Thermal disinfection is also not possible, so adding a disinfection agent is required to achieve disinfection. Till recently, the problem was that dedicated disinfective agents for application in dry cleaning of sensitive garment were not available on the market. However, following market demands, in summer 2021, a group of 3 specialized chemical suppliers for the textile care industry introduced disinfective agents to the market specially developed for application in solvent cleaning processes. These disinfective agents have the following characteristics:

  • Applicable in all leading solvents for dry cleaning, apart from siloxanes (GreenEarth)
  • Applicable in distilling dry cleaning machines (to prevent build-up of the disinfective agent)
  • Virucidal, bactericidal and yeasticidal activity tested according to standards (EN1276, EN1650, EN13727, EN 13624 and EN 14476)
  • Gentle to colours and fibres

The forementioned products are: Desolan ViBac (Seitz), Cinta Sept (Kreussler) and DIAS-OL (Büfa).