Window perf is a calendared adhesive-backed PVC vinyl that is perforated with a pattern of round, evenly spaced holes. The advantage of window perf is that it allows graphics printed on a glass surface, such as windows, to be seen from the outside, but appear invisible to the people inside looking out. Window perf is sometimes called “see-through vinyl,” or “one-way vision film,” but the basic concept is the same.
In most cases the actual size of the holes are uniform (usually about 1.5mm). It’s the distance between the holes that determines the print coverage vs. visibility. For example, 50/50 window perf film means that 50 percent of the material is printable area and 50 percent is perforation. Window perf comes in a number of different hole configurations; 50/50, 60/40 and 70/30 are the most common. The first number in this designation represents the amount of printable area and the second number represents the amount of open (see-through) area. Therefore, a 70/30 window perf has a larger printable area, but less see-through area, than a 50/50 window perf.