Optical microscope images of 22 nm silica nanoparticle films formed at a rotational rate of 2000 rpm and deposited on glass substrates: (a) 480 nm single-coated film generated from a nominal suspension concentration of 22.5 wt % silica. This image displays a fully interconnected crack network in the final film; (b) 494 nm multi-coated film consisting of 14 total coatings deposited consecutively from a 2 wt % silica suspension. Each coating has a nominal thickness of 35 nm. Subsequent coatings were performed with about a 20 min time duration between each deposition. The multi-coated film was observed to remain crack-free throughout its fabrication which is confirmed by this image.