We have now constructed some correction curves for polymer gravure. Before calculating the curve shapes we have worked out our standard exposure times for polymer plates. After applying the curves the image files were printed (as positives) on transparency film. Here we were using an Epson 1800 with all inks, there was no need for finding the best UV-blocking colors here, as we don’t need such high densities for polymer.

Our polymer curves: The first one created by ChartThrob, the second one corrected by hand to reduce posterization of print shadow tones.

Our polymer plate is Toyobo Printight, exposed with UV light first through a fine aquatint screen and then through the positive transparency. Both exposures have to be done with perfect contact between the film and plate, we use a vacuum frame for this. We acquire top quality aquatint screens from Kari Holopainen, a pioneer in polymer gravure in Finland.

After the two separate exposures the plate is developed or “etched” by washing in water, dried, and hardened with another exposure to UV light.

A processed polymer plate. (This plate was pulled through a press once – there is still some ink left in the darkest shadows…)

The plate is then inked with intaglio ink, wiped and printed with an etching press just like any other intaglio plate.

The first print from the plate above. The tone correction curve that was applied to the image file is working satisfactorily, and it can be further corrected, as needed, to match better special type of images.

Next some of our students’ work. Their workflow in polymer gravure is mainly based on these excellent sources:

Polymer Photogravure by Taneli Eskola and Kari Holopainen (or actually its Finnish edition).
Jon Lybrook‘s site Polymer Photogravure for More Photographic Intaglio Prints.

Saara Leppäkoski: Polymer Gravure.

Saara Leppäkoski: Polymer Gravure.

Hanna-Kaisa Kuronen: You Keep Me Sane, Polymer Gravure.

Our polymer gravure process outline:

1. A digital grayscale file is created from the original image. In Photoshop, a correction curve (created by ChartThrob script) is applied. The file is then printed on transparency film as a positive.
2. A polymer plate is cut to the film size. The protective film on top of the plate is removed (in dimmed lightning).
3. The plate is exposed to UV light in contact with an aquatint screen, then with the positive transparency. Our exposures are 80 seconds for the screen plus 80 seconds for the film, but these can vary greatly depending on equipment used – testing is recommended.
4. The plate is then developed by immersing in water and gently scrubbing with hand or sponge. More exposed areas of the plate have been hardened, while less exposed parts will be washed away, leaving “holes” to keep printing ink later. We wash the plates for about 2 minutes in cool water (room temperature).
5. The plate is blotted dry, and an extra uv exposure (ca. 5 minutes) is given (without any films) to harden it for printing.
6. We have basically an etching plate now, ready to be intaglio printed. We will now ink the plate, and while we wipe off extra ink to clean the highlights, the ink will remain in the grooves and produce rich deep shadow tones.
7. An etching paper is dampened and pulled in contact with the plate through an etching press. The paper picks up the ink from the plate and forms the gravure print.