Biopolymer Gels as a Cleaning System for Differently Featured Wooden Surfaces

Abstract

The cleaning of some wooden artefacts can be challenging due to peculiar surface roughness and/or particular finishing treatments that favour the deposition of dirt and contaminants. The most common cleaning system used by conservators is agar gel, characterized by its rigidity and brittleness, which challenges the cleaning of rough and irregular surfaces typical of most wooden artefacts. In this work, alginate crosslinked with calcium (CA) and konjac glucomannan crosslinked with borax (KGB) gels were proposed to solve this issue. They were prepared and applied to smooth- and rough-surfaced mock-ups replicating wooden musical instruments’ surfaces that had been subsequently covered by artificial soiling and sweat contaminants. The mechanical properties of CA and KGB gels, including their stability over a 60-day storage time, were evaluated by a texture analyzer, while cleaning efficacy was analytically evaluated by non-invasive X-ray fluorescence mapping and profilometric investigation. CA gel appeared to have a higher tensile strength and elongation at break. KGB gel was shown to be soft and resilient, indicating its suitability for cleaning rough surfaces. After repeating the cleaning application three times on the rough-surfaced mock-ups, both the CA and KGB gels were shown to have cleaning efficacy. The results obtained with CA and KGB were compared with those from the Agar application.

Removing Aged Polymer Coatings from Porous Stone Surfaces Using the Gel Cleaning Method

“…In Figure 1b, the compressive strength vs. strain profiles of the two specimens are reported. It can be observed that the agar gels and HEMA-MBA/PVP hydrogel were characterized by completely different mechanical behaviors when they were subjected to a uniaxial compressive force: the former showed a fracture zone (peak stress) at low strain values [59], while the latter exhibited a delayed fracture only at the higher level of the considered strain range. Therefore, the agar gel appeared to be more brittle, quickly breaking down, with respect to the HEMA-MBA/PVP hydrogel, which instead showed a longer duration without easy de-structuring [6,[59][60][61].…”

“…It can be observed that the agar gels and HEMA-MBA/PVP hydrogel were characterized by completely different mechanical behaviors when they were subjected to a uniaxial compressive force: the former showed a fracture zone (peak stress) at low strain values [59], while the latter exhibited a delayed fracture only at the higher level of the considered strain range. Therefore, the agar gel appeared to be more brittle, quickly breaking down, with respect to the HEMA-MBA/PVP hydrogel, which instead showed a longer duration without easy de-structuring [6,[59][60][61]. Based on these experimental data as well as the literature data, agar was not considered for the preparation of the emulsion-loaded hydrogels to be applied to the removal of the aged coatings on the stone substrates.…”

Looking for Novel Natural Gels to Improve Cleaning Methods for Bronze Leachates on Marble

“…Our group is also studying the use of konjac, which is also traditionally used in food and cosmetics and can be used for the production of semi-rigid gels. It has already been used to absorb Cu(II) in waste waters in combination with other chemicals [20] and its use in restoration is beginning to be investigated [21]. Therefore, these natural materials can be effective alternatives to agar to improve the cleaning methodologies.…”

Heritage Conservation and Restoration: Surface Characterization, Cleaning and Treatments

“…Therefore, there is high demand to develop smart cleaning tools that can overcome all these limitations. In recent decades, conservation scientists have investigated alternative products such as physical and chemical gel materials based on natural (e.g., xanthan gum, gellan gum, agar, chitosan, sodium alginate, and glucomannan-borax) and artificial polymers (e.g., polyacrylamide and p(HEMA)/PVP)), as well as conducted research into modifying them to act as a transporting medium for different aqueous cleaning systems (micro-emulsions, mixed solvent systems, micellar solutions, and nanoemulsions), which could be correctly used to clean heritage items and overcome the above-mentioned limitations [16,[23][24][25][26].…”