watercolours bought by wife
Take care: the most expensive they are, the longest they last. ( I paint with watercolours for twenty years)
And about printing, I had an experience with postcards a shopseller complained to me about : so I decide to hide half the surface of my postcards and let them exposed to the sun. Afte only two weeks, some of them, all offset-printed, had already faded and turned out to blue, on the contrary others, offset printed too, but elsewhere, are just as they were in the beginning, and it is now one month since I let them under sunrays! Although I am sure about the result, which seems definitive to me, I go on and my best postcards will still remain under the sun until they begin, in turn, to fade out.
Before I did this experiment, I believed that the lasting of the colours only depended upon the printing method. I did not suspected anything about the quality of the inks.