"Printmaker's friend": New emulsion from Calvin Grier to replace gum bichromate

[nmp]

Speaking of Stouffer, is there a similar entity in the form of a half-tone negative that one can use for something like gum.

:Niranjan

 

[TheYoungPretender]

There are some very nice examples of Chiba/Fish glue on flickr by Charles Guerin for those who have not seen those yet
https://www.flickr.com/photos/charlesguerin/albums/72157606697095843 (towards the end).
I believe he has also shared his process instructions.

 

[Ethan Brossard]

I don't have enough knowledge of the chemistry to know if this might be possible, but the way he simply washed the prints to remove the unexposed pigment made me think of photopolymer gravure. Gum printing already uses a polymer to hold the pigment (gum arabic), might he have figured out a way to use a photoinitiator with gum arabic or another polymer? This would also fit with the eco friendly aspect he talks about, and the very short exposure times.

 

[PGum]

Speaking of Stouffer, is there a similar entity in the form of a half-tone negative that one can use for something like gum.

:Niranjan

I suspect that the half-toning of a negative would be highly dependant on the system used to make it: dot size, order and dot gain, so a one size fits all half tone negative would not serve well.

 

[PGum]

There are some very nice examples of Chiba/Fish glue on flickr by Charles Guerin for those who have not seen those yet
https://www.flickr.com/photos/charlesguerin/albums/72157606697095843 (towards the end).
I believe he has also shared his process instructions.

Glad to see someone making it work quite well. Thanks for the link!
Peter

 

[koraks]

Speaking of Stouffer, is there a similar entity in the form of a half-tone negative that one can use for something like gum.

:Niranjan

Calvin sells them from his website. It's a basic 21-step wedge design output onto imagesetter film. You'd have to look up on his webshop which screening option(s) he offers for it. As @PGum indicates there's a lot of variables involved. As I recall Calvin tends to mostly use an amplitude modulated 20um to 40um pitch screen - and different screen angles for different layers obviously, although I do recall having read him using frequency modulation for certain layers. It's all explained in his Gum printing manual why he does it this way.

the way he simply washed the prints to remove the unexposed pigment made me think of photopolymer gravure.

Well, photopolymer at least requires an alkaline wash for 'development', but perhaps this is indeed some kind of photopolymer with some relation chemically to the kind of polymers used for gravure, offset plates and PCB making. However, what would be surprising about this is that those polymers generally (AFAIK) are not water-soluble. I often use photopolymers for PCB etching (as far as I can tell they're very closely related, if not the same as the ones used for photogravure, which I also did some time ago) and they definitely aren't water-soluble. They will dissolve in alkaline water, but I don't think they can be exposed once that's been done - although I could give it a try. Interesting line of thought though! And it indeed would match the short exposures/high sensitivity as you noted.

might he have figured out a way to use a photoinitiator with gum arabic or another polymer?

I have a feeling, given the workflow he presented and the way he formulates its properties, that no gum is involved in this new product. I suspect it's a synthetic polymer alright.

 

[nmp]

Thanks @koraks and @PGum for the info on half tone negs. I was just thinking to use one to test various processes at the development stage. All the nuances may not be that important for that purpose. If any one of them ever got out of testing, then for real pictures those specs can be revisited. I might just look into using Photoshop to "simulate" a half-tone negative and see if that suffices for testing.

:Niranjan.

 

[koraks]

I was just thinking to use one to test various processes at the development stage.

I think the main issue with the kind of screens Calvin sells is that they are pretty high resolution. Printing a coarse screen isn't difficult; printing a 20um one with little to no dot gain is quite challenging. For that reason alone, I'd recommend going with a much coarser screen. I've made some with Accurip Emerald that worked really well at around 88lpi - quite coarse, but at this resolution it's easy to get a decent print even if you don't have full control (yet) over the process. Blocking power with just black on my Epson 3880 pigment printer was/is also more than sufficient for virtually all processes.

 

[PGum]

Thanks @koraks and @PGum for the info on half tone negs. I was just thinking to use one to test various processes at the development stage. All the nuances may not be that important for that purpose. If any one of them ever got out of testing, then for real pictures those specs can be revisited. I might just look into using Photoshop to "simulate" a half-tone negative and see if that suffices for testing.

:Niranjan.

Niranjan,

Attempting to half-tone directly in the image via photoshop will lead to artifacts, as it will compete with the printer’s own half-toning algorithm. You would need dedicated software to take control of the printer, even then there are limitations as koraks points out. If you find a work around I would be interested to know.

 

[koraks]

If you find a work around I would be interested to know.

Yah, me too. You bet. I've spent quite some time researching the issue and all I can come up with is an actual imagesetter. There just doesn't seem to be a good substitute for it.

The closest is actually this:

the printer’s own half-toning algorithm.

Exploit it! I did that (as many other people; I didn't come up with the idea) for photopolymer, just using the black channel of the inkjet and let the dither algorithm of the printer and its driver handle the rest. It results in a quasi-random frequency-modulated screen of in principle good resolution, but with two big drawbacks:
* Dot shape is awful on an inkjet printer. Like, really, really awful.
* Dot gain is awful with an inkjet printer. Like, really, really awful.
They're related, of course, but distinct problems. And significant ones at that.

Oh, and there's the inherent problem with stuff like banding that comes with the territory of using a single channel.

 

[nmp]

Nothing's simple...is there...

 

[koraks]

Well, the whole color carbon adventure has made me somewhat more appreciative of the relative facility of inkjet printing, that's a bonus

 

[PGum]

Niranjan,

Attempting to half-tone directly in the image via photoshop will lead to artifacts, as it will compete with the printer’s own half-toning algorithm. You would need dedicated software to take control of the printer, even then there are limitations as koraks points out. If you find a work around I would be interested to know.

I noticed that Accurip has an 8 day (credit card-free) free trial. Maybe that would be enough for you to run off some test strips.

 

[koraks]

I noticed that Accurip has an 8 day (credit card-free) free trial.

Yeah, that's what I did to try it out.

Btw, there's another option, called Printfab: https://www.printfab.com/en/
It looks promising, and I think they have a 1-month trial period. It does appear that the screening options are all in the most expensive version and I'm not sure if that's part of the trial.

 

[DREW WILEY]

Hide glues have been around long time, and were used for wooden furniture in Colonial times, well before modern glues. Traditionally, they have been based on rabbit skin, but possibly other animal hides. In commercial mixed fashion, they don't keep well for long periods on the shelf, but once used and dry, remain relatively pliable, and hence are still sometimes preferred by traditional woodworkers for flexible veneers. I don't know anything otherwise technical about how they differ from gum arabic or the various gelatins in potential print applications.

Halftone color carbon imaging is nothing new, and there have even been various commercial versions of it, some involving major investments in custom materials and specialized prepress equipment. About all I can say, is that they all ended up looking halftone too, which I personally found to be visually disappointing.

 

[koraks]

About all I can say, is that they all ended up looking halftone too

I don't think a 20um screen pitch will look very bad, really. In fact, it'll be hard to see the dots even with a decent loupe.

 

[DREW WILEY]

Gum or casein printing is a little different because it's so multi-layered and not very overall crisp. But with respect to past commercial halftone ventures involving carbon printing per se, those required a relatively coarse screen to prevent blistering of the layers over time. The halftone pattern was quite evident. In one case, the expensive result was often mocked as "having the beauty of a plastic place mat" - quite unlike the lovely continuous tone handmade prints I've seen. The antique Fresson technique has its own look, which involves a blatant horizontal-vertical screen pattern, rather than dots, along with rather coarse pigments - a look which can be stunning, but not precise.

There have been just so many variations of this theme over the decades. But at least with the older methods, we have the benefit of learning their weak points. Having the most permanent lightfast pigments conceivable doesn't mean a thing if the print cracks and blisters apart after a couple decades.

 

[nmp]

Saidane's on a roll - his Chiba adaptation to Carbon looks pretty good (for my eyes and I am no expert):





Intriguing to me what is he doing (or not doing) that is different from prior efforts by Sandy King and others that did not give good (at least good enough to wean away from dichromate) prints from the ferric carbon process. I have not followed pigment processes with any depth to be able to say.


:Niranjan

 

[koraks]

Intriguing to me what is he doing (or not doing) that is different from prior efforts by Sandy King and others that did not give good (at least good enough to wean away from dichromate) prints from the ferric carbon process.

Well, I'm not entirely sure, because the one thing I'd imagine he should have had a problem with is the lack of an anaerobic surface. This is the issue that I ran into when I tested ferric carbon; the print just won't transfer to the final support if you do it the classic way. Sandy has had good luck exposing the tissue through a transparent support. While Saidane does use a transparent carrier for the tissue, he seems to expose from the top in the regular way - although the video is kind of sketchy on this crucial point.

The one that does stand out in his workflow, in any case, is his use of laserprinter transparencies for negatives. This means he's essentially using a frequency modulated halftone screen, and not a true continuous tone negative. This greatly simplifies the process as highlight retention isn't an issue anymore. As long as you can image discrete dots with good fidelity, all is good. The one caveat here is that Saidane uses black light tubes. If that's true (again, the video isn't specific - perhaps he's using LED strips but calls them 'tubes', which is already a different story), then the diffuse nature of the light would prevent a halftone process from working, and it would sort of revert back to a con-tone process due to diffusion.

So in short it's all rather inconclusive, but very, very interesting for sure - I mean, there's no arguing with the end result which at least in the video looks promising, even though crucial aspects such as rendering of fine detail and tonal smoothness cannot be judged very well.

 

[nmp]

Good points.

Well, I'm not entirely sure, because the one thing I'd imagine he should have had a problem with is the lack of an anaerobic surface. This is the issue that I ran into when I tested ferric carbon; the print just won't transfer to the final support if you do it the classic way. Sandy has had good luck exposing the tissue through a transparent support. While Saidane does use a transparent carrier for the tissue, he seems to expose from the top in the regular way - although the video is kind of sketchy on this crucial point.

If he was exposing from the side of the support, there wouldn't be a need for transfer, right? I think he is doing the traditional way.

If you don't use the barrier, is there like a layer of unhardened tissue at the top - can you not just wash it out before transfer? Would peroxide development itself take care of that?

The one that does stand out in his workflow, in any case, is his use of laserprinter transparencies for negatives. This means he's essentially using a frequency modulated halftone screen, and not a true continuous tone negative. This greatly simplifies the process as highlight retention isn't an issue anymore. As long as you can image discrete dots with good fidelity, all is good. The one caveat here is that Saidane uses black light tubes. If that's true (again, the video isn't specific - perhaps he's using LED strips but calls them 'tubes', which is already a different story), then the diffuse nature of the light would prevent a halftone process from working, and it would sort of revert back to a con-tone process due to diffusion.

I thought Calvin Grier also uses halftone negative. Is he also not reducing the burden on the process that way? I always wondered what was the advantage of using a halftone in a process that is basically continuous.

So in short it's all rather inconclusive, but very, very interesting for sure - I mean, there's no arguing with the end result which at least in the video looks promising, even though crucial aspects such as rendering of fine detail and tonal smoothness cannot be judged very well.

Yeah, things look good on the video. When you try to do it yourself, there might be some show-stopper that might not be obvious from the videos. I am playing around with his hide glue chiba process lately and I am struggling with the quantities he uses and being able to get a good coating - partly because I am a complete newbie when it comes to brushing emulsions (I wonder how the coatings on the videos look so smooth and flawless - Grier doesn't even brush it no more than a few seconds - magic of video?) These gelatin/gum/glue based concoctions don't flow like regular sensitizers we are used to in other non-colloid processes. However, I was able to harden the emulsion - didn't get any steps yet.

:Niranjan.

 

[Andrew O'Neill]

I think I'll stick with traditional gum... I love the smell of Gum Arabic too much!

 

[koraks]

If he was exposing from the side of the support, there wouldn't be a need for transfer, right?

Exactly, and the relief image after soaking wouldn't be visible on the bare surface. So I agree that he must be exposing from the front.

I thought Calvin Grier also uses halftone negative. Is he also not reducing the burden on the process that way?

Correct. It's what he does to manage the problem of what he calls the 'tonal threshold'. These colloid-pigment processes are inherently limited in the faintest highlights they can (not) reproduce. At some point, the exposed colloid layer becomes too thin to survive processing. There's a couple ways to work around this, but the only thing that really helps is halftone screens. Not that continuous tone prints can't be good. Obviously, the can. But if you are really critical when it comes to delicate highlight rendering, they are very, very tricky to get right. Very tricky indeed. Very. (Very!) Halftone screens make the process more robust, but they require very fine screens and excellent printing resolution. So the approach comes with its own challanges.

When you try to do it yourself, there might be some show-stopper that might not be obvious from the videos.

Well, I did, some time ago, and I couldn't get the images to transfer at all. They just wouldn't adhere to the final support. But I have to admit I'm not sure if I actually tried gelatin sized paper for a final support. I mostly tested Yupo and albumen subbed transparencies because my interest in this was/is mostly in the context of a color workflow. If this only works when transferred to gelatin sized paper, the process will only work for single layer monochrome prints. Also nice, btw.

I hear you on the challenges of brushing a colloid emulsion. I tried it on several occasions with gum, and frankly didn't get all that far with it. I did it just enough to determine it takes lots of practice and that special kind of feeling to get the consistency/viscosity of the emulsion juuuust right. Calvin describes this in some detail in his gum printing manual, and it boils down to that he doesn't use any kind of very fancy/expensive brushing. It's basically all technique. He applies with one brush, and then evens out with another one. One of the (few ) benefits of carbon is that it doesn't take this kind of special motor skill.

 

[nmp]

I think I'll stick with traditional gum... I love the smell of Gum Arabic too much!

That's probably the gold standard. I just can't get over having any dichromate around, though. Plus these things are just curiosities for me so I try with most benign systems to start with.


:Niranjan.

 

[nmp]

I hear you on the challenges of brushing a colloid emulsion. I tried it on several occasions with gum, and frankly didn't get all that far with it. I did it just enough to determine it takes lots of practice and that special kind of feeling to get the consistency/viscosity of the emulsion juuuust right. Calvin describes this in some detail in his gum printing manual, and it boils down to that he doesn't use any kind of very fancy/expensive brushing. It's basically all technique. He applies with one brush, and then evens out with another one. One of the (few ) benefits of carbon is that it doesn't take this kind of special motor skill.

Carbon was probably invented by an engineer and gum by a painter....

Oh, by the way, I did get a silk creen emulsion/sensitizer combo and played with a little bit - it's a no go getting any image out of that emulsion. Looks like it is not really soluble in water, more like miscible. I suspect the development in a silk creen is more mechanical than chemical usually requiring high pressure spray of water to dislodge the emulsion where it's not exposed. It's also more PVAc than PVOH and contains an organic solvent to put it all together. I do have 89% hydrolyzed PVOH which I might try. But now I am more intrigued by the Chiba process so that will take precedence if I do any more tinkering in this direction.


:Niranjan.

 

[koraks]

Ah, that's interesting. I also received a screen printing kit which I mostly bought because of the azo sensitizer that came in a separate bottle. It's kind of expensive for how little of the sensitizer you get, but for an experiment it's OK.
I emailed a bit with Kees Brandenburg and he mentioned the screen printing azo sensitizer basically sucks. It leaves a stain that can't be cleared, in contrast to DAS. It's not very high at the top of my list trying it. Let's hope I get there before the stuff expires.
I did notice that the actual emulsion is indeed a PVOH/PVAc mixture. Given this I'm not surprised it doesn't melt nicely since PVAc isn't water-soluble to begin with. Let me know how it goes with the PVOH!