I have a brother HL-L2320D printer, and I was working on a circuit board mask with Eagle PCB.

In the program options I chose to print a solid black PCB artwork. When I use a regular blank sheet of 8.5x11 inch paper in the automatic front feeder, the printout appears fine except a few spots were white when they should be black.

I then rocked the toner cartridge a few times and cleaned the drum unit as per operating instructions. I tried again with another sheet of regular paper but the sheet felt like it was somewhat damp, but not damp enough to crinkle. Anyway, with that somewhat damp paper as my only test paper at the time, I then used it and the printout came out as expected.

Now I proceed to use a sheet of staples transparency and I removed the white tab off of it before putting it into the printer. I put the coating side up so that the toner goes on the smooth side. Once I printed it out, the design came out fine, however the coloring was inconsistent. I expected a straight black image, but instead of straight black, it seems that the black portions are replaced with a darker shade of the same design shifted down the page. It's as if the printer was trying to print the same thing twice in two different formats.

Why would a printer do this when I configured my software and printer to make the output only black? I tried to use the thin paper setting and the thick paper setting for the transparencies and the results actually were worse (and the printer took longer to print the page) on the thick paper setting.

What can I do to fix this?


Getting multiple instances of the image on the page means that the fuser is not applying enough heat to fuse the toner correctly on the paper.

You say you used a transparency. Transparencies require significantly more heat to fuse properly, so it is vital you tell the printer what you are doing. The best way to do that is in the driver. I don't know just how your driver is set up, but, instead of selecting Plain Paper or something similar, set the pap;er type to Transparency. If that selection is not available, try something like Heavy Card.

As for your other problem, most lasers are incapable of printing large solid black areas. You will nearly always find lighter and darker areas in the image. The only way to fix that is to buy a better printer; there are some that will do a near-perfect black. On the other hand, for PCB work you don't normally need a perfect black, and laser prints are usually good enough.

If you do want perfect black, this is the type of work where inkjets produce a better result.

  • My driver gives me the following choices for paper: Plain, Thin, Thick, Thicker, Bond, Recycled, then Envelope Thick, Envelope Thin, and Envelopes. I tried Thin and Thick. – Mike Jul 18 '17 at 2:58
  • You can try "Thicker", but if transparency is not listed, then it's possible the printer does not support it, i.e. it is unable to apply enough heat. – hdhondt Jul 18 '17 at 2:59
  • Wow. So I guess I wasted about $200 for nothing... I can't see thicker working if I tried thin then thick and thick produced worse results. – Mike Jul 18 '17 at 3:27
  • but wait.... wouldn't the ink reach the transparency faster than paper? transparency is thicker. or would I be better off getting special kind of transparencies? I don't want to throw $200 in the garbage – Mike Jul 18 '17 at 3:43
  • I would try all the settings, and use the best one. For inkjets you need special inkjet transparencies. For lasers you must ensure the transparency is laser-rated - inkjet transparencies can damage the fuser. – hdhondt Jul 18 '17 at 3:52

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