Blank Canvasses

I'm keen on right angles and various rectilinear shapes and patterns. I also came across some blank canvasses in some art shops. I had them on a wall for some years interested in what blankness might say. Latterly, they have been stored away somewhere. Over time, they have ceased to be entirely blank - they have changed colour with age. This change in colour through doing nothing and the juxtaposition of the blank canvas within the frame of the photograph (there has been no cropping), I also find interesting.