WetWet objects have a significantly different appearance than dry objects: some have more saturated colors, others acquire a specular highlight. The Wet shader facilitates the creation of this effect by swapping textures for surfaces that are "wet".
Apply a dry-looking texture to the object.
Apply a wet-looking texture to the object. (On top of the dry-looking one.)
In the wet-looking texture's dialogue box, select Alpha-Channel Mask as the blending.
In the wet-looking texture's dialogue box, select Wet as the texture shader; this designates this texture as `wet.'
"Wetness" is specified by either the WaterSurface or Stain shaders; when an object with a texture designated as `wet' is seen through the surface of an object which has either Stain or WaterSurface applied, the wet object will display its `wet' texture. (In the case of WaterSurface, the `Stain Underneath' effect must be selected.)
Note that if the camera enters the water, the textures must be reassigned, as objects that are underwater will no longer be seen through the surface of the water - since the camera itself is now underwater as well. In this case, the dry-looking texture must now be placed on top of the wet-looking texture; also, the Wet shader would be removed from the wet-looking texture and applied to the dry-looking one instead, since this is the texture that the submerged camera would be seeing through the surface of the water. (See the LumeWater tutorial for an example of this procedure.)