I built a frame out of 1/2" x 1 1/2" material I ripped from 2 x 6 lumber. I added shrink window film to a frame I build and then installed the frame with the shrink window film approximately 4 inches from the glass in 6' x 5' windows. What is the best distance to install the film that is attached to the frame from the glass? If the film is to close to the glass, the R-value will be small. If the distance is to far from the glass, eddy currents will form and decrease the R-value. I call the manufacturer but received no useful information.