Water wicking material sugestion needed

[rbarata]

I'm thinking about ways to keep a wood mount permanently damp. I'm tempted to put on its backside a layer of a water wicking material to absorb water from a small container under the mount (with its lower part submerged in it). The idea is the wood to absorb water from this material.

What kind of material do you think woud work? Preferably a neutral and not easily degradable.