(texture idea for walls/art work) texture- this shows texture by making the sand in big bulges. it also could be seen as ripples through water flowing into the middle of the artwork. it also gives a bit of movement into the center.
Not my memory : When I was a kid and a store went out of business, it's windows were whitewashed like this for privacy of the empty space. Even though this pin is a painting, it immediately brought to mind this memory.