## 4 Conclusions  
Monitoring of color changes during the cleaning process of a metal surface by digital images allowed not only qualitative but also quantitative evaluation of the homogeneity and kinetics of the cleaning process. The use of spatiotemporal data analysis for this purpose has a great advantage over other forms of online monitoring of the cleaning process because it allowed the homogeneity of the entire surface and the final quality of the process to be evaluated. The characteristic times defined from the curves of color intensities and variance evolution versus time were excellent indicators not only of the rate of the process, but also of the final homogeneity of the cleaning process. The analysis of these parameters showed how the kinetics of the cleaning process were quantitatively affected by the concentration of the cleaning product, the temperature and the mechanical action exerted, even estimating an activation energy for the cleaning process. Finally, this type of analysis allowed us to obtain an initial estimation of the kinetics of the cleaning process, which were used to estimate the time needed to finish the cleaning process and, based on this, to optimize the experimental conditions. The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app15073745/s1](https://www.mdpi.com/article/10.3390/app15073745/s1)]([https://www.mdpi.com/article/10.3390/app15073745/s1](https://www.mdpi.com/article/10.3390/app15073745/s1)), Figure S1: EDX Microanalysis at different points on the sample surface; Video S1: Accelerated video of the cleaning process by a dissolution mechanism. Video S2: Accelerated video of the cleaning process of a steel sample covered by peanut butter without mechanical vibration. Video S3: Accelerated video of the cleaning process of a steel sample covered by peanut butter with mechanical vibration. C.L., F.L., J.A., J.J.G.-J. and F.V. : Conceptualization, methodology, validation, formal analysis, resources, data curation, writing--original draft preparation, writing--review and editing, visualization, project administration, funding acquisition. All authors have read and agreed to the published version of the manuscript. This research was funded by AVI, Agencia Valenciana de la Innovacion (Valenciana Innovation Agency) in the program for the promotion of talent in line 3 of action, for the support of research personnel in companies for the completion of doctoral theses with the European regional development fund in the INNTA3/2021/24 \"Research into corrosive processes and the accumulation of residues on metal surfaces and the development of preventive hygienic designs for cleaning and \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{3}{c}{**Conditions**} & \multicolumn{3}{c}{**1 st Process**} & \multicolumn{3}{c}{**2 nd Process**} \\ \multicolumn{3}{c}{**for the Cleaning Process**} & \multicolumn{3}{c}{**(Whitening)**} & \multicolumn{3}{c}{**(Peeling off)**} \\ \hline
**T/K** & **Vibration** & **Conc. (\%)** & **f\({}_{0}\)/s** & **t\({}_{1/2}\)/s** & **t\({}_{end}\)/s** & **t\({}_{0}\)/s** & **t\({}_{1/2}\)/s** & **t\({}_{end}\)/s** \\ \hline
293 & NO & 1\% & 160 & 2255 & & & & \\ \hline
293 & NO & 3\% & 20 & 1280 & & & & \\ \hline
293 & YES & 1\% & & & 810 & 1240 & 2030 \\ \hline
293 & YES & 3\% & & & 0 & 500 & 1270 \\ \hline
313 & NO & 1\% & 0 & 4000 & & & \\ \hline
313 & NO & 3\% & & & 902 & 2058 & 2556 \\ \hline
313 & YES & 1\% & & & 460 & 750 & 1040 \\ \hline
313 & YES & 3\% & & & 0 & 177 & 414 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Characteristic times for the process of cleaning peanut butter from steel with the product MF174 UW in concentrations of 1% and 3%, at a temperature of 20 \({}^{\circ}\)C and 40 \({}^{\circ}\)C, and without mechanical action and with mechanical action (vibration). Gray shaded cells indicate that this process was not observed.