Direct to plate polymer photogravure - any step by step guides?

I came across a cheap copy of "Polymer Photogravure" by Clay Harmon (Focal Press 2019) in a charity shop and it has got me thinking about having a go. Other than the press and the consumables I have all the bits and pieces to hand.

Clay Harmon's book is based on making an inkjet acetate positive and using an aquatint screen to make the plate but I've noticed that since the book was published most people (including Clay) seem to be using a direct to plate method, that is inkjet printing onto the polymer plate rather than making a separate positive. I have an Epson R3000 that should be capable of doing this.

When I look for the approach to take to create and print the positive file I'm coming up against a wall. There are plenty of videos on YouTube of people doing this process and a few blog posts but they all jump over the most tricky bit of creating the positive. I need to know how to include the aquatint element in the image. I'm presuming this is because many of the people who do this technique earn a living from workshops. But I'm not a workshop type person and even if I was to do a workshop I'd want to work through the whole process before I took it. I see workshops as for the intangible/ineffable part of the process not the mechanics.

I may be totally missing something but can anyone point me in the direction of a guide to producing digital positives to be printed direct to photopolymer plates? I'm looking for the principles involved as much as the "slide this slider in photoshop" type instruction.

(Of course this is creating a digital positive so may not belong in this forum! I can't put it in the alternate techniques because it contains digital. Maybe it is homeless...)

I'm glad to hear you're still alive and exploring!

I've done only a brief foray into photopolymer intaglio printing and I didn't do DTP (direct-to-plate), but perhaps I can be of help nonetheless. One 'trick' of using inkjet for the halftone pattern instead of a separate screen is to simply use a single channel on the print head - typically black, which generally has good UV coverage. This way, you use the inkjet's halftone patterning as your 'aquatint'. I did it this way with inkjet positives and it should work just the same for DTP.

The Epson print driver has an option to use 'black only', or you could use QuadTone Rip to accomplish the same (and with somewhat more control over what happens).

There may be alternatives, but when I meddled in this process, this is how I did it and the principle worked.

koraks said:

I'm glad to hear you're still alive and exploring!

I've done only a brief foray into photopolymer intaglio printing and I didn't do DTP (direct-to-plate), but perhaps I can be of help nonetheless. One 'trick' of using inkjet for the halftone pattern instead of a separate screen is to simply use a single channel on the print head - typically black, which generally has good UV coverage. This way, you use the inkjet's halftone patterning as your 'aquatint'. I did it this way with inkjet positives and it should work just the same for DTP.

The Epson print driver has an option to use 'black only', or you could use QuadTone Rip to accomplish the same (and with somewhat more control over what happens).

There may be alternatives, but when I meddled in this process, this is how I did it and the principle worked.

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Thanks. That makes sense and would be quite simple.

The requirement of a press is a killer :-/

Richard Man said:

The requirement of a press is a killer :-/

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We have a community printmakers workshop in town and I'm investigating access to the presses there. They don't seem to offer photogravure courses at the moment though.

A fascinating branch of printing.
At one time there was a large community of photogravure practitioners workshopping here in Australia. I am probably going back 20 or so years, remembering their many beautiful works produced in Hobart, Tasmania and exhibited in bespoke Salamanca Place galleries. Fragments of memory seem to recall a few of those works being in colour, but that would be quite the challenge for PG when darkroom printing in colour was still very much in vogue at that time. .

RogerHyam said:

Thanks. That makes sense and would be quite simple.

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Yeah, just give it a try. One thing you may want to look into as well is the collimation of your light source. I ran into this issue when I was doing this process, but I wasn't in a position back then to solve it. It would have been different today with high-power COB UV Leds easily available. A key issue you may run into with photopolymer is that of dot gain, which essentially means that light bleeds around the inkjet dots, creating cone-shaped light bundles within the photopolymer substrate. This results in problems like false biting when developing the plate, but also gross non-linearities in the transfer curve, requiring a very strong adjustment curve. To make matters worse, the effect can be variable across the plate esp. if you print using a film-based positive, as the contact between the plate and the film varies. This should be no problem of course if you do DTP.

The problem can be avoided/reduced by using a collimated light source. The sun is a good one, but point sources like old-fashioned plate burners will also work. Modern COB LED sources will work if you put the printing frame at some distance to the light source. I expect that if you use a more diffuse or multi-point light source, i.e. UV tubes or strips of UV LEDs, you will run into this problem. However, having said that, I think that several contemporary photopolymer printers are using UV LED strips for their light sources, so apparently the effect can be sufficiently consistent to still allow good linearization. Personally I'd still strive for a collimated/point-source light source to avoid the problem as much as possible.

Btw, there are some active photopolymer people on the forum; I think e.g. @KYsailor and @Graham06 fall into this category. Perhaps they can share their experiences here.