If you find a solution to your proplem, please post it here. We also have mysterous brown spots accumulating on our night shades. We tried to clean one of the spots with a damp rag and light pressure, but, the shade started to come of in layers. Our shades appear to be made out of some kind of paper product.
We are now afraid to use any cleaning product for fear that the shade will fall apart or melt.
Dale & Betty
04 Lapalma 33'