Redo with Aquatint

This evening, I made a second plate using an aquatint screen. The second plate has more subtle texture and variation in the line widths and does not produce lines with open bite.

Here’s the second plate. This plate was exposed first with an aquatint screen and then a second time with the artwork. In this plate, the lines are made up of microscopic pits, instead of open grooves.

The plate with aquatint shows more subtle variation in the line widths.

For comparision, here is the original artwork, the print from the aquatint plate, and the print from the first plate.

This is the artwork that I used for the plate exposure. My goal is for the prints to match the original artwork as closely as possible.

The second plate makes use of aquatint. Here there is a greater variation in line width and all lines print without open bite.

This print is from the first plate. That plate didn’t use aquatint and may have been over-etched, resulting in open bite and thicker lines.

Starting a New Print

I just made an intaglio print based on one of my favorite line drawings. The original charcoal drawing is from my time in Geoff Flack’s Foundation Figure Drawing course back in 2010. I made the plate last night from a piece of SolarPlate. The results were decent for a first attempt, but I think in the end I failed to capture the subtlety of the line drawing. My next attempt will be an aquatint, which hopefully will more accurately reproduce the softness in the charcoal lines.

This photopolymer plate works like a classical etching in copper, where the grooves hold the ink and the smooth surface is wiped clean. I’m concerned that I will get open bite in the shoulder area because the lines are too wide. Open bite happens when the groove is so wide that the capillary forces in the ink are unable to hold the ink in place as the plate is wiped. I’m still investigating why the lines in the shoulder are so thick. It could be the original artwork, or I may have over developed the plate.

The first step in printing intaglio is to apply ink to the plate. I like to use a scrap of cardstock to help push the ink into all of the grooves.

Here I’m starting to wipe the plate with a piece of tarlatan (basically a piece of cheesecloth that has been heavily starched). The goal for this pass is to remove the heaviest ink deposits while grinding the ink into the lines.

After removing the bulk of the ink with the tarlatan, I switch to newsprint which removes surface ink while leaving the lines. The newsprint also tends to polish the smoother parts of the plate.

At this point, I’ve wiped with tarlatan, then newsprint. All that remains is to clean up any ink that has stuck to the edges of the plate.

Here’s a close up of the plate immediately before printing. I’m a bit concerned that the fingernails are holding too much ink.

Here’s the first print, on a scrap of damp Rising Stonehenge. As I suspected, there is some open bite in the lines of the shoulder, and the lines in the fingers are not as subtle as the original artwork. The grey rectangle is called plate tone and is created by the residual ink on the plate. Plate tone is one of the hallmarks of the intaglio process. In this test print, I over-wiped the bottom of the plate, leading to uneven plate tone.

Why ImagOn?

I am sometimes asked why I put so much time and effort into learning to make plates from ImagOn when I could be using high-quality, ready-made photopolymer plates like SolarPlate or Toyobo KM plates. The reason has to do with my artistic vision which involves large, two, three, and four foot intaglio prints made from multiple plate impressions using image decompositions similar to those found in reduction linocuts and Moku Hanga. I chose intaglio over relief methods because I wanted to create tonal gradients unavailable in linocuts and textures unavailable in woodcuts. I also wanted the ability to incorporate very small details that are hard to obtain with hand-cut relief plates. Seriography and lithography were also options, but intaglio felt like the most promising technique for the images I have in mind. Also I love the embossing.

ImagOn is a challenging material to master but it has two huge advantages which are potentially unlimited plate size and lower cost. Ready-made plates are simply not available in the sizes I need and those sizes that are available run about $0.20 per square inch, compared with ImagOn which costs $0.02 per square inch. ImagOn is currently available in 24″ wide rolls and if I can tolerate a seam, I can butt together two pieces of ImagOn to create a plate almost 4′ wide.

My vision involves large prints, but I make lots of smaller prints along the way and for these I still prefer ImagOn because of its lower cost. My rationale is not as simple as merely saving money – one could argue that the time I spend designing and executing a print is worth more than I would would ever spend on plates and paper and ink.

The real reason is psychological and it has to do with creativity. Because ImagOn is inexpensive and I make the plates myself, nothing is precious and I am free to experiment to my heart’s content. I know that I am more careful when using a large piece of SolarPlate or painting on an expensive canvas. With ImagOn, I don’t even think about ruining the material and this leads to greater output and more paths followed.

I have been using Mark Nelson‘s Precision Digital Negatives process to calibrate my ImagOn plate making process. Most PDN users are from the alternative photographic process world and those that work with photopolymer are typically trying to achieve a “printerly” effect in a piece that is essentially a photograph. My use of ImagOn and digital stochastic screens is unusual for this community. For the most part, their goals are to reduce grain in the image and render very subtle tonal changes across the entire range. I want this, too, but my images aren’t photographic in nature so I am much more willing to sacrifice grain and tonal subtleties for the ability to print large. Also in many cases, I deliberately incorporate coarse aquatint texture into my designs.

I do require absolute control over my processes because I am making a huge investment in time and money to put together a large print from multiple plates. In order to remain creative, I need high confidence that my 4′ plate will work as planned. PDN gives me this confidence.


Imagon Improving

Tonight I tried printing my ImagOn test plates on damp Rising Stonehenge and found that I was able to get full ink density in my prints. I am still somewhat puzzled as to why I can get full density on dry paper using SolarPlate, but not ImagOn. In addition to this difference, I found that ImagOn has much higher contrast when compared to SolarPlate. ImagOn seems to do a great job reproducing the aquatint structure in the matrix and it seems capable of producing very fine detail. The ImagOn emulsion does seem more delicate than SolarPlate, and it is very easy to accidentally scrape off some of the texture. It is also easy to chip the edges of the plate. Photos below document my observations.

This ImagOn film is laminated onto a piece of transparent PETG plastic. The transparent plate has a number of advantages – you can easily see inking problems and it offers opportunities for easy, but precise registration when printing with the plate on top of the paper.

For this session, I made exposures of a Stouffer step wedge after first exposing the aquatint screen.

This plate used my best aquatint exposure, followed by an exposure of the Stouffer step wedge. A decent aquatint pattern has developed in the matrix.

Another closeup of the aquatint pattern.

I am puzzled by the blue globs of emulsion sitting on top of the aquatint matrix on the left side of the image in steps 7 and 8. I could try rubbing them off during development, but am worried that I might damage the matrix.

The test strip on the left is printed on the smooth side of dry Masa paper. The strip on the right is printed on damp Stonehenge. Clearly it is possible to print a maximum density black using ImagOn and damp paper. I am puzzled as to why I can get maximum density from SolarPlate on dry paper.

The test strip on the left is SolarPlate on the smooth side of dry Masa. The strip on the right is ImagOn printed on damp Stonehenge. The ImagOn seems to hold a finer grain in the aquatint, but it is very contrasty, compared to the SolarPlate. This is a case where the Precision Digital Negatives approach should really shine. My guess is that it will recommend a really low UV density ink like red in order to control the contrast.

This closeup shows the fine detail that is possible with ImagOn. This is as good or better than prints I have made with SolarPlate.

More Imagon Tests

I’ve been trying to establish a baseline exposure for the aquatint screen. In my earlier session I had a lot of trouble getting consistent results and good ink transfer. After considering a long list of hypotheses, my conclusion is that my almost empty jar of ink was too old and its gummy consistency was playing havoc with my plate wiping.

For this evening’s session, I decided to eliminate as many variables as possible. By the end of the evening, I got some good plates that printed pretty well, but I was still not able to get the density of blacks that I can reliably attain with SolarPlate.

One top theory is that the Akua Mars Black which I used for the SolarPlate tests has greater optical density or better wiping characteristics than the Akua Carbon Black that I have been using with the ImagOn. This will be easy to investigate once I get another jar of Mars Black.

The other theory is that the ImagOn emulsion simply cannot hold as much ink as SolarPlate because it is only 50 microns thick, versus SolarPlate which is almost a millimeter. The main evidence supporting this hypothesis is that I get my greatest density when the channels in the plate go all the way to the plastic.

I am printing on the smooth side of dry Masa paper, so I’m pretty sure that the Imagon will give adequate blacks on wet Rising Stonehenge, but I would still like the ability to get fully saturated transfers on dry paper if possible as using dry paper will help me with multi-plate registration by eliminating paper expansion and contraction due to moisture levels.

My next experiment will be to determine the proper baseline exposure for the second exposure. Once I nail that exposure I can proceed with a standard PDN calibration.

I has having a lot of problems with my previous test strips that used a single exposure, simultaneously through the Stouffer wedge and the aquatint screen. For this evening’s experiments I eliminated some variables. Instead of using the Stouffer wedge, I went old school and used a strip of cardboard to create a sequence of exposure times. I also increased the size of the exposed blocks to 1″ square and I added a fully exposed margin to simplify the plate wiping.

In this closeup of the two test strips side by side you can see the overexposed margins that I added to simplify wiping. I found it was really helpful to make bigger plates with one inch square steps. My Stouffer wedge has 1/4″ x 3/4″ steps which are sometimes hard to evaluate.

This is a closeup of a dual exposure plate from my last session. I exposed once with the aquatint screen and then a second time with the Stouffer wedge. In this example, the aquatint is underexposed. You can see this in the region around the numbers which is solid black on the Stouffer wedge. For this area to print black, it will need a more robust dot structure to avoid an open bite. It is interesting that an underexposed aquatint screen can still make fairly dense halftones as you can see on the right. Also, note that the underexposed aquatint has led to an uneven dot pattern on the right.

This step is underexposed to the point of open bit. Here the aquatint screen has produced a field of isolated islands. With more exposure, the islands will merge and make a field of holes and channels. Another indication that this plate is underexposed is the bare plate on the left. At this level of exposure it is very easy to lose the emulsion entirely.

This step is overexposed. The channels appear blue because they no longer go the full depth of the emulsion.

This step is about right. The islands have merged and there are lots of channels to hold the ink. The damage to the dot field indicates that it still may be slightly underexposed. In general, I want to get a really sturdy matrix without exposing to the point that the channels start to lose depth.

Experimenting with ImagOn Film

Recently I have been experimenting with ImagOn Film for intaglio plate making. ImagOn plate making is tough process to master, but it has some advantages over SolarPlate, including cost (about $0.02 per square inch vs $0.20 per square inch for SolarPlate) and the possibility of making really large plates. ImagOn is less forgiving than SolarPlate, so I am ramping up slowly.

As with SolarPlate, my first goal was to come up with a repeatable process from exposure to development to printing. This post shows my progress in determining the correct exposure.

My main challenge so far has been to get an adequate black from just the aquatint screen. The blacks that I have been able to achieve so far are not nearly as saturated as those from my SolarPlate tests. My general impression is that my ImagOn plates have less etching than my SolarPlates. This may be because of a problem in my process or it may just be an inherent property of ImagOn to which I will have to adapt. More experiments will give me clues.

ImagOn is a a film consisting of a 0.002″ thick layer of photopolymer emulsion sandwiched between two protective layers of plastic. The first step in making an a plate with ImagOn is to laminate the emulsion to a metal or plastic plate. The process is easy, involving water and a squeegee, but it must be carried out away from any sources of ultraviolet light.

One of the differences between ImagOn and SolarPlate is the color of the emulsion. This plate uses ImagOn Ultra which is a blue like French Ultramarine. ImagOn HD is green. The emulsion for this plate is laminated to a piece of clear acrylic, giving it a very different appearance from SolarPlate which sits on a an opaque steel plate.

The transparent blue ImagOn Ultra plates are quite striking.

This plate is underexposed, but it gives a good idea of the layout of the step wedge.

Here you can see four test strips with different exposures. The second from the bottom has the most exposure, giving it a saturated blue color due to the thicker emulsion. The top plate is underexposed and consequently has a very thin layer of emulsion.

Intaglio printing is always a slow, messy business. This disaster is my studio after an evening of test strips. I will get the process dialed in and it will get better, but for now I need to plod along with the calibration.

Color Gradient Experiments

I’ve been working on some new print designs that use atmospheric effects and interesting skies. To make these prints, I need to be able to make smooth color gradients where I can change hue, saturation, and value across the page. Today I did some experiments with two-color gradients.

Each of these two-color gradients was made by printing a single gradient plate two times in with different colors and orientations. The effect works pretty well with lighter colors, but I notice that the gradient does not appear as smooth with the darker colors.

The experiment involved a 4″ x 5″ photopolymer plate with a linear gradient running from full ink at the top to clean plate at the bottom. My process was to print the plate in a light color, then rotate the plate 180 degrees and print it again in a dark color. The goal was to get a smooth transition from the dark color to the light color.

After printing so much black and white, it was refreshing to see all the colors. The prints were attractive and I was pleased to see that I could make a blue to yellow gradient without getting green in the middle.

My main problem was that my gradients weren’t very smooth. They look as if the plate is somehow mottled or even scratched. I have a number of theories but it will take some experiments to sort things out.

Here are the leading contenders

  • Over-wiping the plate
  • Non-uniform wiping
  • Color inks require a different wiping technique than black ink
  • Ink consistency
  • Not enough printing pressure
  • Plate got damaged during development
  • Poor contact between plate and aquatint screen during exposure
  • Poor contact between plate and positive during exposure

My plans are to print the plate with a known good black ink, on the small press where I am more familiar. I will use a lot of printing pressure. If I still see the problem, I will print a known good plate to verify that the problem isn’t with the press and ink.

Then, depending on the results, I may make a second gradient plate and see whether it shows the same problems.

First Photopolymer Gravure Plates

After completing the Precision Digital Negatives process calibration, I was finally ready to make my first photopolymer gravure prints! For this initial round, I chose two designs – one using solid black and solid white and the other using the full value scale. The plates were 4″ x 5″ SolarPlate, exposed first with an aquatint screen and then again with a positive which was printed onto Pictorico OHP.

This photopolymer gravure plate contains no gray scales – it only has solid black and solid white.

I liked this design a lot, but was a bit underwhelmed by the print. It doesn’t know whether it wants to be photograph or a graphic. The idea still has potential so I’ll take it back to the drawing board. I think I will go with simplification over photo realism.

This plate is from a photograph of an ice covered pond in Boston. The plate uses the full range of gray values, calibrated with Precision Digital Negatives.

The print came out really well, especially given that it is from my first round of photopolymer gravure prints, using Precision Digital Negatives for the first time, and using the Glen Alps press for the first time.

David and Goliath

I finally got a chance to use the Glen Alps Press for the first time. It has been over a month since the press arrived, but before I could make prints I needed to get new felt blankets and level and adjust the press. Today I made my first print on the press – it was a 3″ x 5″ photopolymer gravure plate.

I chose this photopolymer gravure plate for the press inaguration.

The giant press makes the 4″ x 5″ plate look miniscule.

Here’s the big reveal of my first print on the Glen Alps press.

Precision Digital Negatives

Musicians practice scales before concertos. As an art student I practiced value scales in vine charcoal before attempting to render a sphere. Now in the printmaking domain, I am doing the same thing, only this time I am working with Mark Nelson‘s Precision Digital Negative (PDN) process to calibrate my photopolymer platemaking and printing process.

No matter how you do it, process calibration involves lots of test strips.

The goal is to develop a repeatable, end-to-end process starting from the creation of the original artwork, to exposing and developing the plate, through the final printing step. There are many variables that impact contrast, texture, the range of values, the richness of the blacks and the purity of the whites. I want to be able to control each of these variables in order to make the print that I see in my mind’s eye.

The PDN system is a general process for calibrating the production of digital negatives and positives for alternative photographic processes that use ultraviolet light to expose the final image. Mark has put a huge amount of effort into developing and refining the PDN system. His e-book is excellent and chock full of details and explanations of the process itself and related topics like image acquisition and preparation and Photoshop tips. The e-book also comes with membership to a PDN discussion forum where you can get answers to most questions. If you are making digital negatives or positives, I highly recommend purchasing the PDN book.

Creating photopolymer plates for intaglio requires exposure to a positive, rather than a negative. I print my positives onto a transparency film called Pictorico OHP, using an Epson Stylus Pro 3880. I use two types of plates – ready-made SolarPlate and plates I make by laminating ImageOn film to sheets of acrylic. I expose the plates using an old Nuarc 26-1K platemaker that I picked up on Craig’s List.

I’m most of the way through calibrating my SolarPlate process. Once I have the SolarPlate process refined and stabilized, I will repeat the calibration for the more complex ImageOn process.

At a high level, the PDN calibration process involves 4 steps:

  1. Determine the correct exposure time for clear film.
  2. Determine the mixture of ink colors in the transparency that yields the ideal density range for exposing the plates.
  3. Generate a gradient scale using the ideal color mixture
  4. Generate a set of Photoshop level adjustment curves that linearize the gradient scale.

The photos below document my journey through the initial SolarPlate calibration.

The first step is to determine the correct exposure for clear Pictorico OHP film. One could do this by experimenting with a bunch of different exposure times, but it is much quicker to make a single exposure through a step wedge that incorporates a variety of calibrated neutral densities which simulate shorter exposure times.

Here’s the step wedge plate, inked, wiped and ready to print. The darker portions of the wedge correspond to darker regions on the plate. Each step in the wedge corresponds to 1/3 f-stop.

When exposing positives for photopolymer plates, it is important to choose an exposure that just hardens the plate so that it prints pure white in areas where the film is clear. The exposure for this test strip is spot on, but it is apparent that I have a contrast problem because the plate goes from white to black in about four f-stops.

It turns out that black inkjet pigment is not well suited to producing fine tonal gradations in most alternative photographic processes. The problem is the black is just too strong and the printer can’t generate enough different gray values in the narrow range required by the photopolymer plates. Imagine trying to render a figure with a Sharpie and you get the idea. Mark’s insight is that one can choose a mixture of much weaker color inks in order to produce a positive with densities that match the response curves of the plates. By using color inks, it is possible to create hundreds of distinct values across the entire range from white to black. This is a huge improvement over black inks which are so dense they can only create a handful of distinct values in the densities useful for plate making. The squares in the test strip above represent about 150 different color mixtures. The goal is to choose the mixture that just barely yields black.

Here’s the color test strip, printed on white paper. Each of the gray boxes corresponds to a different color mixture in the inkjet positive. I chose the forth box from the left in the row labeled B=255 + R=0-255. This box corresponds to a the RGB color R=30, G=0, B=255. This color mixture just barely manages to give me black when it is at maximum intensity. Lighter versions of this color give me lighter shades of gray.

Here’s the plate for the initial gradient scale. This plate was created from a positive that used a mixture of red and blue ink, instead of black. Each square on this plate is a different shade of the RGB color R=30, G=0, B=255.

Here’s the initial gradient scale, inked, wiped, and ready to print. Already it is apparent that the plate has a contrast problem – most of the plate is very close to either black or white – only a tiny portion in the middle shows distinct gray levels.

This is the initial gradient scale, printed on white paper and showing 100 different levels from white to black. This scale is not very linear – it is quite flat in the whites, then shoots up quickly to the dark grays and then flattens out again in the blacks.

This plate was created from a new positive which combined the original gradient with the PDN process adjustment curves. The process adjustment curves should linearize the gradient.

As you can see here, the linearized gradient plate looks much smoother.

This gradient was produced by applying Photoshop process adjustment curves to the original gradient. This curve is much closer to linear.