Agar gel loaded with micro-emulsion could be used to extract lipophilic materials from porous surfaces. The physical properties of the gels are good enough for a conservation work. They allow the micro-emulsion to flow on the porous surface and to wet it but maintain the micro-emulsion in its structure and prevent the formation of rings. https://safeersappliancers.shop/product-category/neff-d94qfm1n0b-n50-built-in-90cm-3-speeds-a-chimney-cooker-hood-stainless-touch/