Wet Wipes Testing Laboratory | Sigma Test and Research Centre



Wet Wipes Testing Laboratory

Wet Wipes Testing


Wet Wipes, also known as moist towelettes, are little wet paper towels that are used to clean the hands, refresh the face, and most often to clean up the diaper region while changing a baby’s diaper.

Wet Wipes the initial versions were sold in little individual packages and were frequently saturated with scented water to give them a pleasant aroma.  Although the rubbing movement did assist in getting the hands or face a bit cleaner, many individuals found that they were more useful for refreshing than for cleansing.

Wet wipes testing – are a developing business with new uses being developed all the time. They are becoming widespread in our daily lives.

Wet wipes:- We clean with them, apply solutions with them and use them to disinfect surfaces. We use them on ourselves, in our homes, in hospitals, and in many other businesses.

And notably, during the Covid Times, they have become more than common and undoubtedly the need of the hour for many houses in terms of cleaning and sanitation with wet wipes.

Two international test standards have been created to assess prostrated wet wipes. ASTM E2362 – 15 Standard Practice for the Evaluation of Pre-saturated or Impregnated Towelettes for Hard Surface Disinfection, which is employed by the EPA to validate disinfectant wipe claims through the utilization of contaminated test surfaces and prostrated wipes.

Wet Wipes Testing:

The wipe is applied to ten or sixty contaminated test surfaces. Following incubation, the number of test tubes harboring the target microorganism is calculated. At least 59 of 60 surfaces washed with the towelettes must demonstrate thorough disinfection to pass the 60-carrier test (no visible growth of the target microorganism in the tubes containing neutralizing growth media) (no detectable growth of the target microorganism in the tubes containing neutralizing growth medium). To pass a ten-carrier test, all wiped test surfaces must be fully cleaned.

Wet Wipes test, like the AOAC spray test, has substantial flaws; comparable to the AOAC spray test, there is variability based on statistical analysis alone, and key test parameters are not standardized (e.g. humidity levels during drying, the concentration of bacteria on the test surface) (e.g. humidity levels during drying, the concentration of bacteria on the test surface).

While the wet wipes test contains mechanical action, which is more indicative of in-use settings, cleaning several surfaces with a single wipe until the disinfectant is depleted does not duplicate the wiping routine in a cleanroom.

Additionally, the test does not account for differences in the amount of pressure and technique applied to wipe the test surface.

ASTM E2967-15 – Standard Test Method for Evaluating the Ability of Pre-Wet Towelettes to Remove and Transfer Bacterial Contamination on Hard, Non-Porous Environmental Surfaces It is hoped that the use of the Imperator, a more recently invented prostrated wet wipe test, may help to reduce some of this variability by employing a repeatable mechanical action for wiping created by the “Imperator.”

Falafel and Ottawa University’s Centre for Research on Environmental Microbiology created the Imperator, which they claim improves consistency as compared to manual test approaches by accurately regulating the applied force, rubbing speed, and wiping duration throughout the test.

During the test, the wet wipe testing revolves at 1 revolution per second in an orbit with a 10 mm diameter and oscillates over a 6-degree arc.

The wet wiping continues in 5-second intervals up to a total of 45 seconds. It is assumed that there is a default contact force of 150 g between the wipe sample and the wiper, which corresponds to a rubbing force of 800 g or more in a real-world wiping situation (an accessory 150 g weight permits testing 300 g forces).

It is arguable whether or not this adequately simulates the force and method with which a wet wipe is used in a cleanroom environment.

Three independent laboratories tested five different types of commercially marketed prostrated wet wipes, each of which was shown to be effective. All five wet wipes (four detergent and one disinfectant) decreased germs by more than log 4, but only the disinfectant wet wipe prevented bacteria from being transferred to another surface after contact with the wet wipe.

They discovered that by using this standard approach while testing prostrated wipes with mechanical action, they were able to attain greater precision and reproducibility. Although the test is frequently used in the United States, it is not commonly utilized in Europe to assess cleanroom prostrated wipes.

Until recently, there was no EN standard for measuring the efficacy of disinfection wet wipes. However, in 2015, EN1661513 was published as a carrier test for detecting if a wipe is bactericidal or pesticide, and it is already in use.

Despite the fact that it is meant for prostrated wipes, it is possible that the wet wipes will get saturated with the chemical under test at the time of application.

There are a variety of approaches of including an interfering chemical to replicate both clean and dirty conditions. In addition, the contact time may be modified between 1 and 60 minutes depending on the situation.

The wet wipe is wrapped around a 2.3–2.5 kilograms granite block in order to standardize the wiping technique and to simulate the average pressure produced while cleaning.

On a PVC sheet, the block is wiped over four predetermined fields to create a pattern. The organism has been dried in field number one.

In a single, seamless motion that takes two seconds, the granite block is pushed through all of the fields and returned to the starting point. It is required that a log 5 reduction in the number of bacteria or a log 4 reduction in the number of yeasts be achieved during the testing on field 1. In fields 2–4, each organism must have an average carry-over of fewer than 50 cuffs on a given day.

A large number of laboratories in the United Kingdom have now verified this test process, contributed more data and gained a better understanding of the test.

Pre-drying specified test organisms on a test surface and wiping the product onto the test surface with a wet wipe testing were the goals of the test technique, which was developed with the goal of accurately simulating practical application conditions, such as contact time, temperature, and interfering chemicals. A major aspect impacting wiping efficacy, according to the laboratory that created the test method, was determined to include wet wipe material testing, wet wipe quality testing, impregnation volume, application pressure, and application technique, among other things. The technique had to be adequate for differentiating between wipes, and that was the goal of the project.

Disinfectant manufacturers hoped that the test method would demonstrate that there is no risk of cross-contamination when using a disinfectant wipe, as well as that it would establish compatibility between the wipe substrate and the disinfectant active, which we previously identified as a particular issue with the previous test work.

Disadvantages that might arise:

Some unexpected results were discovered during the first testing, demanding a further in-depth investigation. In addition, significant discussions on the exam were held with the test house that was hired to complete the work in question (MGS Laboratories, Gasport, UK). When submitting a product for testing against EN16615, keep the following points in mind:

If the manufacturer or facility does not specify a special wet wipe to be used with the fluid under test, a typical industrial wet wipe will be used, which may or may not behave as a cleanroom wipe. The standard calls for a wipe that is made of 55 percent pulp and 45 percent polyethylene (PET).

The wipe will be wrapped around the granite block in a single layer if no specifications are provided; however, this may not correspond to how the wipe is used in your cleanroom.

The wipe will be saturated with a 16 ml solution if neither the size nor the substrate is given. This has the potential to have a significant influence on the result. In the laboratory, some of the early failures were caused by a lack of fluid being released from the wipe, either because the wipe was not properly saturated or because the wipe failed to release the active fluid. In fact, even numerous wipes soaked in cleaning solution will only release a trace amount of fluid to the surface, because a wipe optimized for particle pick up is saturated just enough to break the binding layer of fluid between a particle and the surface, but not so much that it causes the particle to return to the surface.

In order to avoid becoming unmanageable with drips, wipes suited for surface disinfection must be adequately saturated to be able to deposit a visible layer of disinfectant during the requisite contact duration. The substrate of the wet wipe testing has an impact on the quantity of fluid that is absorbed and released to the surface as well.

Unlike organic materials, which may absorb liquids into the hydrophilic fibre itself, synthetic materials such as polyester can absorb liquids into the interstitial spaces between the fibres.  As the fibre size of synthetic wipes (polyester and polypropylene) is reduced, they become more absorbent in general, with microfiber items being the most absorbent of the lot.

Synthetic fibres such as polypropylene, for example, are ideal for achieving a regulated discharge of a solvent. The amount of fluid that is discharged onto the surface by the wipes is not measured in this experiment. A simple solution to this problem would be to weigh the wetted wipes before and after the testing session.

In addition, the test method does not include a detailed description or confirmation of the swabbing approach that will be used to collect bacteria and viruses from the test squares.

As specified in the standard, the whole surface of each test field must be rubbed with two swabs, one dry and one wet, and then rubbed again with a dry swab until the test field appears to be clearly dry after each rub.

A maximum of one minute per test field should be allowed for the complete operation. Performing swab recovery differently amongst laboratories would most likely result in the greatest disparity in results between labs in this area.

A feasible improvement would be to use contact plates to check that the swab recovery phase was successful.

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