A method and apparatus are provided for implementing non-destructive quality control of substrates and printed biological microarrays. A method and apparatus are provided for implementing quality control of gel-based microarrays prepared by dispensing a gel-forming composition on a solid substrate. The method utilizes the difference between the wettability properties of a supporting substrate and a gel, where the gel is hydrophilic. Condensation of vapor of a chemically inert water-soluble liquid, such as water or glycerol, on the surface of a substrate under inspection creates a layer of tiny droplets that affect both transmission and scattering of light on the surface. A pattern of condensation, characterized by spatial distribution, average size of the droplets and spacing between the droplets, reflects variation in wetting properties of the substrate. The pattern of condensation circumscribes printed microarray features to be non-destructively imaged and analyzed.