Quantifying the ‘press and peel’ removal of particulates using elastomers and gels

Elastomers and gels have been proposed for the gentle 'press and peel' cleaning of soil or grime from substrates of cultural and/or historic significance. However, there has been limited understanding that connects the physical and chemical properties of these soft materials to the required physical properties for removing adhered particles from surfaces. In this work, we quantified the cleaning efficacy for a range of elastomers and hydrogels in order to probe the effects of material chemistry, elastic modulus, thickness, and the number of repeated cleaning treatments on the removal of artificial soil from a substrate. We developed a quantitative measure of cleaning efficacy via a simple experimental method that relies on image processing of the interface prior to and after cleaning to measure the removal of soil particulates. The results suggest there are two material requirements that must be satisfied for a successful cleaning: 1) efficient contact with soil particulates on the substrate and 2) favorable chemical interactions with soil particulates to facilitate their removal. Cleaning efficacy is enhanced by decreasing the effective stiffness of the material. Repeated cleaning treatments on the same spot with pristine material can also further remove artificial soil with each subsequent application. In order to highlight the applicability of soft, solvent-free elastomers for cleaning applications, a commercially available silicone elastomer was used to remove particulate contaminants from a historic wax cylinder.