Fine Pore Structure Characterization in Two Gessoes Using Focused Ion Bean Scanning

Abstract

The movement of fluids through a porous medium is a function of the material type and the size and morphology of the voids. In the conservation of painted artworks, the movement of materials (for example, cleaning solutions) is a major factor in how a work reacts to treatments and a large influence on how the work will change with time. Of particular importance in the conservation of painted surfaces is the preparatory layer. This is a highly active transport medium because it is generally highly porous and a comparatively large and uniform component of a painted surface. In this work, a gesso film of calcium carbonate and rabbit skin glue, typical of the preparatory layer of many painted works, and an acrylic-based gesso film were imaged by focused ion beam (FIB) scanning. The gessoes were milled and scanned with gallium ions serially, in sequential planes orthogonal to the plane of the film. This yielded quantifiable measurements of the fine internal structures at a resolution far higher than previously reported for this type of material. This enabled a greater understanding of the geometry of the internal surfaces, increasing the understanding of the mechanics of capillary flow and diffusive behavior in this extremely common and significant material.

Far‐reaching geometrical artefacts due to thermal decomposition of polymeric coatings around focused ion beam milled pigment particles

“…In the past, FIB-SEM has been used for site specific cross sectioning and/or lamella extraction for transmission electron microscope imaging (White et al, 2001;Lins et al, 2002;Loos et al, 2002;Beach et al, 2005;Brunner et al, 2006Brunner et al, , 2008Brostow et al, 2007;Kawahara et al, 2008;Martínez et al, 2008;Wong et al, 2010;Firpo et al, 2015;Qin et al, 2015), destructive tomography (Kato et al, 2007;Lin et al, 2012;Olea-Mejía et al, 2012) and nanofabrication (Aubry et al, 2002;Niihara et al, 2005;Lee et al, 2012;Schmied et al, 2012;Orthacker et al, 2014;Schmied et al, 2014) of polymers and polymeric composites. Out of these examples, only a few studies have been dedicated to characterization of pristine organic coatings and paints (Lins et al, 2002;Brunner et al, 2006Brunner et al, , 2008Brostow et al, 2007;Lin et al, 2012;Chen et al, 2013;Doutre et al, 2014). With respect to corrosion barrier coatings, FIB-SEM characterization can provide quantitative nanoscale information about three dimensional distributions of pigment particles and pores in both pristine as well as corroded samples.…”