Imbibition and Evaporation of Water Droplets on Paper and Solid Substrates

Abstract

Imbibition and evaporation of picoliter (pL) sized water droplets on paper media commonly used for inkjet printing is measured using high speed imaging system. Three types of uncoated and coated paper samples were chosen: multipurpose uncoated paper (80 g/m2), matte coated paper (230 g/m2, and gloss coated paper (240 g/m2. As a reference, the rate of the evaporation process was quantified by using three impermeable solid substrates with different wetting characteristics, i.e., silicon, glass, and hydrophobized glass. It is shown that for water droplets of about 60 pL, imbibition is the dominant phenomenon on the matte and gloss coated paper leading to a total drying time (imbibition plus evaporation) of 10–15 ms for gloss coated paper and 30–150 ms on the matte coated paper. In the latter sample, different regimes in the imbibition process were correlated with the layered structure of the sample. The drying process on the multipurpose paper is dominated by evaporation, with initial drying rate of 0.4–0.6 pL/ms.