I’ve had the samples sitting for about six months, just to make sure the paints were really dry. They were dusted off and given a light coat of beeswax to finish sealing them, as I do with the painted drinkware. So far, they’ve had an easy life.
As expected, the acrylic stuck to both samples. What I wasn’t ready for was the way the oil paint seemed to be just sitting on the surface on the modern dyed piece. It smudged when I hit it with the wax. The gouache is having some problems the other way around. In that case, the modern one is fine but the iron black sample seems to have thinned the coating somehow. Possibly it’s reacting with the paint.
I’ll keep on with the tests as planned. Tomorrow might be a good time to leave them out in the rain.