*2.4. SEM and EDX Characterization*

The morphology and elemental distribution of the plate before and after the cleaning were examined with SEM and EDX, respectively [14]. A Hitachi SU3900 Large Chamber Variable Pressure SEM combined with an Oxford ULTIM MAX 65 SDD X-ray analyzer was used. High resolution (up to 100 k X magnification) [15] FE-SEM imaging was performed using a Hitachi SU8230 Regulus Ultra High-Resolution Field Emission SEM. Selected areas on the daguerreotype were imaged using FESEM (image resolution of 0.6 nm at 15 kV acceleration or 0.8 nm at 1 kV acceleration).
