Stability. Despite the absence of added stabilizers, the Au NPs colloids are stable for weeks as detailed in Figures , where the UV-vis spectra of the as-prepared NPs and the UV-vis of the same batch after 7 months of storage at RT in a drawer are almost the same (the measurements were performed without active homogenization of the sample prior to the measurement). This is line with the stability of SF NPs prepared with 20-30 v.% stable for years . While the stabilization mechanism(s) of the Au NPs is still to be fully established, electrostatic interactions seem key and the contribution of species such as acetaldehyde (oxidation product of ethanol) cannot be ruled out .