We have a fence that was built behind our house, which was included in the house purchase/construction. It is built with upright slats with equal spacing between the slats as the slats are wide. A row of slats on both sides of the fence, alternately placed. Now, we would like to make the fence fully opaque even when viewed from the side. Currently, there is full transparency if viewed from the side. In another house we previously lived in, the neighbor had built a similar fence but had some kind of black paper or similar material behind the slats that made the fence fully opaque. Does anyone have an idea of what material that could have been?
Thanks in advance!