Eva Ekerot Nov 5, ’19 < 5 min

How to reveal the soil removal efficiency already during the cleaning test

One way to assess the soil removal efficiency of a surfactant or formulation is to run a cleaning test of a soiled surface and thereafter run an analysis of the cleaning result. It is however possible to shorten this evaluation process by combining these two steps and run them simultaneously. Here we show you how.

Monitor the soil removal during the cleaning test

Using a time-resolved technology, i.e. a technology that measures at the same time as the process is taking place, it is possible to monitor the soil removal during the cleaning test and get the result directly. Not only will this approach save time, but it will also eliminate the manual handling of the surfaces in between the test and the analysis, and, it will reveal new information on the soil removal process.

Experimental setup and execution of a time-resolved measurement

An example of a method that could be used for this assessment is QSense® technology, which provides information on the soil removal with nanoscale sensitivity.

The soils to be assessed are coated onto sensors and mounted into the measurement equipment together with the cleaning formulations to be analyzed. Next, the setup is programmed with the wash sequence to be executed in the cleaning test. When the wash sequence starts, the soil removal is monitored in real-time, Fig 1. This enables a direct comparison of the soil removal processes and performance of the formulations used.

QSense cleaning efficiency analysis

Figure 1. Using a time-resolved technology, the soil removal process is monitored as it takes place and the result is obtained already during the cleaning test.

Comparing the performance of two different detergents

As an example, let’s have a look at the results from a test where the soil removal by two detergents, A and B, was evaluated. The results are shown in Fig. 2, where the soil thicknesses are plotted as a function of time.

  • Starting at soil thicknesses of 100%, the introduced detergents will wet the soils and result in thickness increase (~15 min).
  • The subsequent thickness decrease reflects soil removal
  • The water rinse (~40 min) reveals the amount of soil remaining at the surface after the cleaning.

Comparing the behavior and performance of the two detergents, the soil thicknesses reveal that detergent B acts faster than detergent A, but that it has a lower overall cleaning efficiency. It is also noted that detergent A causes more initial soil wetting, than does detergent B.

Q-Sense_Detergent A and B for blog

Figure 2. The graph shows the soil removal by two different detergents, A and B, which is monitored as it takes place during the cleaning test. The plot, which shows the soil thickness as a function of time, reveals both the soil removal process and the cleaning effectiveness of the two detergents. Water was used as a negative control.

Concluding remarks

Using a time-resolved technology to analyze the soil removal, the information on the cleaning efficiency will be obtained already during the cleaning test. Not only will this method offer additional information in terms of detergent behavior and soil removal dynamics, but it will also save time and eliminate a manual handling step potentially interfering with the tested sample.

Read more about the soil removal evaluation and comparison in the case study 

Case study  Analyzing cleaning of hard surfaces with QSense  Download

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