From Paris comes news of a new class of surfaces that (among other things) offer better control of coffee stains. Details are in the study:
“Slippery pre-suffused surfaces,” A. Lafuma and David Quéré [pictured here], EPL (Europhysics Letters), vol. 96, no. 5, 2011. The authors, at Laboratoire de Physique et Mécanique des Milieux Hétérogènes, CNRS, Paris, France, report: “We describe the slippery behaviour of textured solids filled with oil, on which other liquids are found to slip and be removed easily. We describe the criteria for achieving this slippery behaviour, and illustrate the concept by two examples, namely the lotus effect (removal of dust by mobile drops) and the coffee stain effect.”
This detail from the study shows how a coffee stain on a traditional surface (left) differs from a coffee stain on one the new surfaces (right):
(Thanks to investigator Tom Gill for bringing this to our attention.)