There are special transparency films you need to use to print your image on: a drafting film for use with a laser printer, or a specially coated transparency film for inkjet printers. The setting you should select is not “transparencies” but “glossy photo paper,” or whichever is the highest quality your printer permits. We have found that an inkjet printer gives the best results in terms of crispness and denseness of the print. If you already have a printer, use it to print a sample and hold it up to the light – the black areas should not let light through.
-Ruth Dobbins, Professional Glass Consultants