I am not happy ( before Zak makes the comment - I don't know which of the other dwarfs I am ) the sails have now been soaked in tea and have a good colour BUT they are very even, with no colour difference.
The photo of the square sail has had coffee granuals soaked onto it - the triangular one has been painted with very small drops of vallejo paint onto the material and then lots of water added to wash it into the sail.
I think the coffee one looks more natural !!!!!!!!