POSSIBILITIES OF
POLYMER PHOTOGRAVURE

by KARI HOLOPAINEN

PREFACE

Polymer photogravure is a method based on the innovation of Danish printmaker and artist Eli Ponsaing, 1989. Ponsaing's main innovation was to understand that polymer plates produced for letterpress printing could successfully be used in intaglio.

In polymer photogravure traditional pigment paper and copper is replaced by light-sensitive photopolymer resin plates (Toyobo printight KM). The polymer plates are printed in the same manner as traditional etching plates. The process requires a darkroom, a high quality etching press and a good UV vacuum frame. If darkroom conditions are not available, it is possible to make positive originals on plastic foils or on glass surfaces.

In my own work I have concentrated on developing the qualitative possibilities of the method when photographical images are used. In many countries, polymer photogravure is still a new method and rarely used although it can give brilliant printing quality with a full range of tones from white to velvety black. Compared with traditional photogravure (heliogravure), the new method is much faster and more secure. This is because there are much less variables in the new polymer photogravure method.

THE POLYMER PROCESS

exposition

1. The original negative is placed in the enlarger with the emulsion side down An easel is used to hold the image positive film flat and in the focal plane of the projected image.

development

2. The image positive film is exposed and developed in a traditional paper developer; then taken to spottable and fix. After fixing the film is washed for 5 minutes. It is then taken to a Kodak-fotoflo solution and dried.

Several types of continuous-tone films can be used successfully. We have been using e.g. Bergger, Agfa Gevarex and Arista films. For very soft images we recommend using litofilms developed in a very diluted developer, e.g. Neutol 1:50.

3. The density range is measured in the densitometer. In this process, images should have a density range of 1,2. The density range is measured from the lightest areas to the darkest greytones that should be visible in the print. If the density range is larger than 1,2, tones will vanish either from the light or the dark areas of the picture, depending on the kind of an exposure given for the image at the UV exposure stage.

4. The polymer plate is cut to the right size. If a suitable cutter is not available, the plate can be cut with a sharp blade and a steel ruler.

5. The protective film is removed from the polymer plate.

6. The image positive is placed on the emulsion side of the plate.

7. The polymer plate with the image positive film is exposed in the UV vacuum frame. There are very many types of UV vacuum frames and contrast results vary a lot depending on the kind of frame you use. UV tubes often produce quite contrasty results and powerful UV halogen frames softer results. All work with continuos-tone film is affected by the machinery you use!

8. The positive film is removed.

9. A screen exposure is given with an aquatint or stochastic screen in the UV vacuum frame in perfect contact with the polymer plate. Good contact is essential at this stage, if you want to avoid problems later. (For line drawings screen exposure is not needed if the lines are not too thick).

10. The exposed plate is placed in water of 24°C for one minute.

11. The plate is developed gently with a sponge or the hand in warm water for another minute. The unexposed parts will dissolve in the water, producing pits and hollows in the plate. The UV light has hardened the highlights, making them insoluble.

12. The plate is rinsed carefully in cold water to get rid of leftover polymer.

13. The plate is dried carefully between several sheets of clean paper. All water drops left on the plate will be visible later in the print!

14. The printing plate is hardened under ultraviolet light approximately 5 minutes.

15. The consistency of the printing ink is measured with a palette knife. When the consistency is right the ink normally drops slowly from the knife.

16. The plate is inked. The ink is carefully worked into the hollows.

17. Excess ink is wiped from the plate using soft paper or tarlatan cloth. The plate is finished with the palm of the hand.

.

18. The plate is printed in a copperplate etching press. Dampened paper is placed on the wiped printing plate. Under hard pressure ink is transferred to the paper. For excellent results a high quality press with hard pressure and good blankets are needed
The final print

The finished print.