If you noticed the watercolor on the wall between the two windows in the lounge then we have a bit more information for you. The blue is cobalt, the light brown is saffron and the dark brown in burnt sugar. This video is how the sugar is burnt onto the paper. First it is painted as a sugar water and allowed to dry so it appears invisible. Then a flame is carefully applied and you can watch the image gradually appear.
Burning sugar water onto paper
