Capillary bonding of wet surfaces - the effects of contact angle and surface roughness

Capillary bonding of wet solids through a water film is common and important for a variety of problems. An existing experimental technique for the measurement of capillary bonding forces was improved and used to show how fractional wetted area and capillary bonding force vary with water 'tension' for glass, polyethylene, and aluminum on porous ceramic. The effects of contact angle and roughness were explored. The results show that increasing the contact angle clearly reduces the capillary bonding, but the effects of surface roughness were much more complicated. Roughness can increase or decrease capillary bonding, depending on the exact conditions.