Still using the same tube of Sennelier ultramarine I bought in Paris in 2003. The crimp at the end is almost completely folded over now, every week I squeeze it a little flatter and think this is the last canvas, and then there's always a little more. I've moved twice with that tube. It survived a marriage and a divorce and a second one. Probably thirty canvases have a bit of it in them somewhere.

I keep meaning to buy a fresh one. And I don't, because somewhere in there I've decided the old one is the better colour, which is nonsense, it's the same pigment, same batch probably. But you know, the tube itself has the right temperature now. A new one would feel cold.

My wife thinks this is sentimentality. It isn't. It's superstition, which is a different thing entirely.