Backlit film is a special print medium designed to be used in lit signs and other backlit applications. It is typically glossy on one side with a matt finish on the other. The matt side is designed for reverse printing so the mirror image is transferred to the back side of the film and then the front of the film shows the normal image when lit from behind. Printing on the glossy side should be done with normal settings. The matt finish on the back will still diffuse the light from behind to create a white background for the colour image to show against.
Put on the cotton gloves to avoid fingerprints or finger oil on the film. Take out one sheet of the film. If you are using a laser printer, load the film so the matt side will be printed; if you are using an inkjet printer load the glossy side to be printed.
Set up the image you wish to print. If you are using the reverse printing method you will need to create a mirror image. In your image-editing program, select the option to flip the image horizontally.
Select "File" then "Print" to open the print dialogue box for your printer. Use the highest photo settings available, selecting either glossy or matt paper settings depending on the side you are using.
Allow the film to dry completely before handling it.