A litany of woes – digital inkjet negatives and a note on dot gain mottling

I’ve sworn many times to myself that I’d steer clear of digital negatives if at all possible. Really. It’s not out of a lack of familiarity with them. Quite the opposite. I must have printed hundreds upon hundreds of them. They gave me maybe a handful decent prints, virtually all of them cyanotypes. But sometimes, there is virtually no choice but to go there…

Many moons ago I bought a second-hand Epson 3880. It made its way neatly through all the nozzle checks, the price was right, I felt at the time, so I made it mine. Amazingly, it still works. Alright, it has become a lot more challenging to ace a nozzle check, but mostly, regular prints still come out fine. That’s what I initially got it for as well. I felt the need to print, and shooting mostly digital at the time, inkjet was the logical choice. Everything changed soon after; I got (back) into analog/film photography and I got into alternative process printing. The Epson was a convenient tool (so I thought) to make digital negatives on transparency material to print my cyanotypes, Van Dyke Browns, and later carbon transfers and even photopolymer intaglio’s.

But boy, did I thoroughly dislike the whole digital negative thing. In principle, the flexibility of digital image manipulation is just great. Most of the things I envision I pull off a whole lot quicker in Photoshop or even GIMP (despite its thoroughly *annoying* user interface!!) than in the actual darkroom. There’s just so many layers (literally!) of control you have over the end result. To merely press a button, feed a sheet of plastic through the printer and get a perfect negative handed to you in return is pure magic. Well, it really is, because that’s not really how it works, at least not for me.

Let’s see what kind of issues a digital negative maker without infinitely deep pockets (no LVT film recorded or imagesetter here in this house…) like me runs into on a typical day when making digital negatives:

  • Your usual ink-wasting black ink changes (resolved in newer printers, I understand).
  • Empty ink cartridges and full maintenance cartridges. Yes, I switched over to Job Cone refillable carts and their inks years ago, otherwise I’d have been bankrupt by now.
  • Print job settings strewn across many screens and resetting to an unidentified default at random, making it necessary to triple-check on each print job if Epson and me are still on the same page (hah!)
  • GIMP not being able to print properly to begin with, at least not from Windows 10. Lack of support for custom paper sizes, limiting to a ridiculously short and useless list.
  • (Notice we’re actually getting the printing part now after getting all the equipment to get ready and actually operational.)
  • All manner of printing issues, either minor or a little less minor:
    • Clogged nozzles, whether temporary or permanently. Run many sheets of paper through the machine and have it flush another hectoliter of ink down the drain to try and resolve the issue.
    • Head alignment issues. Too bad, this one’s permanent. Requires a $1k head replacement using a print head that hasn’t been manufactured anymore for years. Alright, we’ll live with the minor defects inherent to every print.
    • Oops, out of ink on one channel. Order some new ink from the US. Does arrive pretty quickly from inkjetmall.com these days, I must say. Which of course is another way of noting that apparently still nobody offers a decent 3rd party ink set for these printers in mainland Europe.
    • Pizza wheels marks. In a stroke of genius, Epson engineers decided it would be nice to scale down the Wartenberg wheel so popular in BDSM dungeons for use inside an inkjet printer. Yes, they systematically torture every sheet of paper you feed through the printer with them. Leaves particularly nasty trails on glossy papers and in particular transparency materials. You’d say that after about 15 years of complaints about the issue, Epson would have woken up to it and thought of a different solution, but as I understand, the little torture wheels are still a ‘feature’ of Epson’s desktop printers offered today.
  • Specifically on transparency sheets:
    • Ink never quite drying out on transparencies. It always remains slightly tacky and tends to stick to carbon tissue. From there, it transfers neatly to the actual print if you’re ‘lucky’, creating nasty spots.
    • Density being rather limited to begin with, in comparison with silver negatives. I’m using ConeColor’s K3 set because I also want to be able to print regular color prints with this machine and their (as well as Epson’s original ink set’s) UV density is borderline sufficient for carbon transfer. If all else works out A-OK, it’s sufficient, but that’s all.
    • Reticulation! For digital negatives and in particular for carbon transfer, you want to lay down a lot of ink to have some decent UV opacity. It so happens with the transparency materials I’ve used so far, it doesn’t really matter how far you turn down the ink density dial, the ink will always reticulate horribly during drying. Great, so instead of printing a solid black (well, more of a dark grey in the best case scenario), I get a micro-scaled mudflat pattern.

Now, the latter issue, that of reticulation, I hope to be able to solve by using a proper transparency material. I’ve read good things about both Pictorico OHP and Fixxon’s. Pictorico can be had around here, but it’s even more pricey than it is in the US – and it’s not exactly cheap there either. Fixxon’s is unobtanium here in Europe, but there’s still eBay, so I ordered some and hope to get it later this month. If that doesn’t work, let’s see if I can get some screen printing transparency stuff to work. I need to be able to print an uninterrupted patch of black (with acceptable density) to create pure whites in a print. If this fails, I’ll throw in the towel, like I did a few years ago. Back then, I got into large format and very quickly found out that a real negative just leaves any inkjet printed piece of *** biting the dust.

So my position is fairly clear, I’d say. Yes, the critic would say that much of this is due to compromises in materials. There are better printers out there than my (t)rusty 3880. Although many of the fundamental problems remain. Yes, I could decide to convert from K3 color to one of the several monochrome ink sets for better UV blockage. I’d have to get another printer to do normal work. Great, now I’ve got two ink-slurpers occupying space I don’t want to spare. Did I mention that even at the budget approach I’m taking, the Epson has already drunk about three times the money in ink that I spent on the initial purchase? No, one printer is enough, thank you very much. Yes, I could have just splurged on a decent transparency material. Well, no contest here; I’m trying. Let’s hope the Fixxon’s makes a difference. I tried several materials a few years ago and they all performed poorly (to say the least; basically, there was virtually no difference between them and they were all utter cr&p); let’s hope Fixxon’s really is something special.

And then of course there’s the oddball issues. Such as this one (but this I think I can handle):

Carbon transfer test chart. With many issues, indeed, but let’s focus on the mottled vertical bar marked ‘0’ on the right side for a bit now. Image size is around 4×5″

Now, this if you ask me is a classic example of what is called ‘dot gain mottling’. The thing is, inkjet is still as a friend of mine calls it, ‘splatter printing’. It’s tiny droplets of ink being splattered onto a surface in a very tightly controlled way. So my digital negatives are made up of all these tiny little dots, which in fact is the main fundamental problem to begin with in terms of image quality in several ways, but let’s set that aside for a minute.

If you then expose those dots with a diffuse light source, as for instance a bank of UV tubes at close distance to the contact printing frame, you sometimes get these interesting interference patterns, caused by some of the inkjet dots being imaged larger than others in the final print. It has to do (probably) with some of the light ‘seeping’ past the ink dots in varying angles, and the intensity of that effect apparently varies across a surface. If this happens, a little more gelatin gets exposed than should be, making the dot larger in the print than it should be. The problem generally stands out the worst at a certain dot frequency or size, which is why it tends to show up in some tonal values quite strongly, and less so or not at all in others. Let’s zoom in on that print for a bit:

Close up of dot gain mottled area

Here we see the problem in its full glory. Well, in fact, it’s multiple problems. First and foremost, this issue wouldn’t even have existed if this part of the digital negative had been a contiguous black patch as it’s intended to be. But due to the limitations of the combination of this ink (both photo black and matte black do this, in various degrees of severity) and this particular transparency material, there’s a reticulation pattern going on, which creates the black channels between the white patches. The contrast is also too low, despite using a very low concentration dichromate sensitizer, and exposure was aimed at making a good black, so the reticulation problem stands out exceptionally well here.

If you look closely, you can see that the lighter and the darker areas are really made up of dots being imaged fairly reliably (the lighter areas), and places where there’s a lot of light leaking past and underneath the dots, making the canals between them merge into one another. This is the actual dot gain: it’s the dark ‘dots’ (so more of a striped pattern here, which has to do with the direction of travel of the print head; another annoyance that this kind of mechanical artifact shows up in a print) being larger and even merging together in some places.

As I said, it’s mostly due to the light source I used, and it’s also (not) helped by the ample exposure. The print above was done with my back of UV tubes, which I already knew would be problematic in this regard with inkjet negatives. I had run into this issue in a very, very bad way with the inkjet positives I used back in the time for photopolymer intaglio. So I switched over to the cheap UV LED light source, dialed in the exposure a bit better, and the problem was gone. Just like that!

So in the hopes of eliminating the deal-breaking problems one by one this time, I’m giving inkjet negatives one more try. Just once. And let’s pray that it works out and they fulfill their promise. Fingers crossed…

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