Inkjet printers work great for making transparencies used in photoresist methods for PCB's. Unfortunately, I made transparencies less frequently than needed to keep my inkjet cartridges from drying out and decided to develop a method that would work as well with my laser printer. My printer is an HPLaserJet 4101mfp. It cannot be adjusted to make dense transparencies.

The method I developed uses a black dry erase marker to make the image on the transparency more opaque. It does not smudge any of the lines or other details. It simply fills in the grain on the transparency. Dry erase markers are most commonly used on white boards when making an oral presentations. That is, they substitute for chalk used on black boards. I use Expo brand. I have not tried other brands. Expo was the cheapest at my office supply store. Permanent markers will not work. The procedure is simple. Just paint over the entire laser transparency on the toner side, let it dry, and wipe off with ...