Adding drops of humble old water into solid materials can actually increase their strength and changes their other properties in interesting and useful ways. Researchers from Yale have discovered that adding droplets of water into some solids can strengthen and stiffen them, by virtue of their surface tension.
The force is often observed in fluids, and its role is typically to reduce the surfaces area of the material. Embedding small droplets of water, each around a micron in size, into solids means they can make use of this force. It's a kind of restoring force, always attempting to keep the droplets as small as possible so in turn resisting extension, and stiffening the lump of water-infused material.