Jiri Borsky wrote:
The explanation: Water and other liquids conduct light in a different way
to air. When the wood (soil, fabric, etc) is wet, it reflects light
differently from when dry. Usually it appears darker, as more light rays
penetrate deeper via the liquid filling the spaces and get absorbed there.
When the liquid evaporates it is again replaced by air (with smaller
refraction coefficient) and the surface appears lighter.
To retain the darker "wet" appearance you would have to fill the pores
of dry wood with some non-evaporating substance, such as wax.

Fantastic. So you'd apply wax once it's dry?

I'm off to view your paintings in Didsbury on Monday .... )