by Friedhard Kiekeben 1994 – 2025
- Material, equipment and facilities
- Laminating photopolymer plates
- Troubleshooting in the lamination process
- Material, equipment and facilities
- Laminating photopolymer plates
- Troubleshooting in the lamination process
Intaglio Type is the name given to film-based photopolymer processes developed by Keith Howard. It encompasses any intaglio technique that utilise dry photopolymer film. There are also other photopolymer intaglio methods using ready-made industrial flexographic plates: solar plates etc. These have different –sometimes more toxic– chemistry and processing.
Photo-etching reinvented
Intaglio printmaking is not so readily associated with the use of photographic materials and processes as is lithography or screenprinting. This is somewhat surprising considering that photogravure, the earliest method established to reproduce and print the photographic image, was invented in 1879. This process which is essentially a photographic aquatinting technique, was to have a huge influence on industrial printing but like other photo-etching techniques since then, it failed to become a major means of artistic expression in intaglio printmaking. The reason for this is twofold. Firstly, the love of tradition has sometimes prevented etchers from assimilating reprographic materials and methods; something that screenprinting, unburdened by historic precedents, embraced wholeheartedly. Secondly, photo-etching processes used to be very technically demanding, time consuming, expensive and often involved the use of a number of hazardous materials.
As a result of the innovative etching methods spearheaded by Keith Howard and others, a range of entirely new reprographic intaglio techniques are now available to artists. These represent not only a straightforward way of transferring photographic material or other prefabricated imagery into etching but they also form the basis of an entirely new intaglio medium. The new techniques are extremely versatile and enable the artist to use any kind of reprographic mark, image or stencil in etching. The high sensitivity of the new processes ensures that every detail and tone registers truthfully on the resulting print.
The photopolymer medium offers great benefits both to etchers who wish to combine the more conventional intaglio techniques with photographic elements as well as to those artists who favour a modern graphic style but were previously
deterred from intaglio printmaking because of its somewhat laborious technicality. The basic materials of this medium are photopolymer films which have been developed by several large chemical companies for use in the circuit board industry. In their original context, these films are laminated onto copper plates and etched to produce circuit boards and microchips. In accordance with the very exacting standards of the electronics industry, the films are extremely corrosion resistant, hard wearing and most importantly, able to reproduce any matrix exposed to it with incredible accuracy. The new materials commend themselves to printmakers for just these reasons and also because they are:
- inexpensive
- easy to use
- extremely versatile and art medium
- and have a well documented industrial record of safety when used correctly
The photopolymer films are acrylic polymers, which makes them fully compatible with other aspects of acrylic based etching. Acrylic stop-out varnish and aquatint can easily be used in conjunction with them. Plate preparation and stripping processes are also similar to those used in intaglio printmaking. The photopolymer methodology has similarities with the reprographic transfer techniques used in screenprinting.
METHOD
The basic photopolymer method is as follows:
1. Firstly, the chosen image is generated or transferred onto acetate, tracing paper or another translucent material as a positive. As with other reprographic processes, the quality of the positive is absolutely crucial to give the best result on the plate and ultimately in the finished print.
2. Next, the positive is exposed to a plate laminated with photopolymer film by means of ultra violet light. This usually requires a vacuum bed and a UV light source, but for less technically demanding projects even sunlight can be used. The UV exposure hardens all those areas of the photopolymer film that are translucent and not covered by the opaque marks on the positive. At the same time, all those areas that are protected from the UV by those marks remain in the unhardened state of the film.
3. When exposure at a predetermined length of time is complete and any protective layers have been removed from the film, the plate is immersed in a mildly alkaline developing solution. Developing in this instance is very different from ordinary photographic developing processes – it is, in fact, more akin to the eroding etching process. All the marks hardened by the UV light are resistant to the dissolving action of the developer and remain proud on the surface of the plate. All the unhardened areas are simply washed away by the alkaline solution, revealing the surface underneath onto which the film is laminated. Due to the thickness of the film, the plate has now acquired a raised surface of marks and corresponding intaglio recesses.*
4. After drying, follow the usual procedures of using mordant resists as on any other etch ground. Those areas where metal is exposed will be eroded into deep intaglio grooves while areas covered by photopolymer marks will remain as an untouched metal surface.
5. After etching, the film can be either be stripped off and the plate to be printed as an etching, OR the film can be left on the plate thus becoming the intaglio printing surface (see the Non-Etch process).
*A photopolymer plate already resembles an etched plate after developing and can even be used for printing at this stage. In order to do this, the plate may be further hardened by being exposed to UV light once more. This can be done simply be laying the plate in sunlight for 15 minutes or more. During this exposure period the acrylic polymer chains of the film become more complex, creating a surface that is even more durable and mordant resistant. After light hardening, the plate can be inked up as an ordinary etching plate and printed in the usual way. With experimentation, the variables of this non-etch process (i.e. the kind of positive used and the exposure time) can be controlled to produce linear and especially halftone intaglio prints of the most astounding quality.
To anyone used to the physically demanding and time consuming nature of conventional etching, the ease and speed with which intaglio images can now be produced is astonishing. A positive made by using a photocopier, for example, can be processed and turned into an accurately reproduced intaglio print in less than an hour.
A single non-etch plate can print an edition of about 40 to 70 prints, but because of the speed and simplicity of the process, plates can easily be remade to extend the size of an edition. Non-etch plates are also ideal for color printing for this reason, and because they are inert and do not interfere with any colored inks.
Material, equipment and facilities
The films
Photopolymer film is widely used in the computer and electronics industry but has only fairly recently been picked up by the suppliers of art materials as a specialised printmaking product. Commonly, the film is manufactured for industry in large rolls. The two main producers used to be DuPont and Omi/Hitachi but today many more films are available for printmakers. Keith Howard’s photopolymer films have undergone about 15 years of research and development especially for their use in printmaking.
Keith began using a DuPont film called Riston in the mid 90s. It was a superb materialfor all of the new photopolymer techniques. Today, his latest ImagOn comes in various thicknesses and sizes.
The Omi/Hitachi manufactured film is known as Photec but is only available in Europe. Other brands specially designed for printmaking include Puretch, the Z-Acryl photopolymer films, and the Grafisk Eksperimentarium films from Denmark. (2025 update:).
The film can be ordered directly from the manufacturers but minimum orders can be relatively large in quantity and expensive. Orders are often placed by workshops or college departments which can sell on smaller quantities to participating artists or students. The film is suitable for line and tone work and can be laminated onto any number of hard materials that can be run through an etching press.
Most types of photopolymer film come in three layers; the actual bluish coloured photopolymer emulsion is sandwiched between two layers of clear Mylar film to aid storage, handling and lamination of the material. Both layers of Mylar are removed during the processing stage. Supplies of film should arrive and be kept in a lightproof cardboard tube, and ideally rolled around an inner tube to prevent creasing.
Photopolymer film is mainly sensitive to the UV part of the spectrum and so its light sensitivity is very different to photographic film. It can be handled in subdued daylight or artificial light so long as no direct sunlight or other source of UV is present. The ideal set up facility is a separate room with yellow lighting of normal brightness. Windows or other sources of stray UV light can be temporarily blocked out with transparent red or yellow PVC sheeting.
UV Exposure Unit
This piece of equipment is often shared with screenprinting. Extra precautions should be taken to protect the glass top of the unit from photo etching plates by covering it with clear acetate. Also the rubber cover of the vacuum bed needs to be protected from sharp metal plate edges by laying a felt blanket on top of the plate. In larger workshops it makes sense to provide a custom made facility for photopolymer work. Ideally this should be incorporated in an enclosed yellow room (which can also be combined with a conventional dark room) and contain a tabletop vacuum frame with a UV light source suspended from above.
MATERIALS
Products and equipment needed for photopolymer printmaking:
supplies of photopolymer film
crushed soda crystals (household washing soda) to make up the developer
high quality positives on transparent base (line, halftone or continuous tone depending on
requirements)
goggles
photographic developing trays and rinsing facilities with hot and cold water supply
tank or container for storing ready-made developer (a plastic keg with tap is ideal)
blade cutter
scissors
masking tape
tubes for storing photopolymer film
simple hinged folders, slightly larger than the plates, for transfer of undeveloped
photopolymer plates to and from the press
etching press with foam blanket for laminating
enclosed room with yellow or subdued lighting (often a darkroom space can be used or adapted)
Laminating photopolymer plates
Before any work can be exposed a sheet of photopolymer film has to be laminated onto the chosen base material. In the case of etch techniques the base, for obvious reasons, has to be a metal plate which is prepared in the usual way.
METHOD
The BASIC method for laminating photo-polymer plates as follows:
1. As in the hard ground technique it is crucial to give a tooth to the acrylic resist by roughening the plate surface with sandpaper – ideally using a sander. Use about 350 gritfor copper, zinc and aluminum and about 200 grit wet and dry paper for steel.
2. A thorough degreasing is equally important and a 45 degree bevel can also be given to the photo etching plate at this stage, or prior to printing. It is, however, strongly advised to also apply a slightly shallower bevel to the back of the plate so that no blankets will be cut when the plate is being laminated.
3. The plate surface should now be treated with a mildly acidic degreaser such as CPS degreaser, (or similar), applied with a clean paper towel, or with a mild solution of acetic acid or similar, to create the right surface climate for good adhesion of the acrylic polymer film.
4. The prepared plate is now transferred to the room/area with subdued or yellow light conditions. Here, cut a piece of photopolymer film that is slightly larger than the plate – an overlap of about half an inch is sufficient.
5. Now the first layer of clear Mylar film has to be removed. With Riston and ImageOn film,
stick a piece of masking tape on the inside curling edge of the film. Carefully pull and peal away the soft top layer of Mylar and discard.
6. Once the soft Mylar film is removed, place the sheet of photopolymer film onto the prepared metal surface with its matt side facing down.
7. Carefully smooth down the film and transfer the plate into a light fast folder.
8. Turn the folder upside down so that the plate now rests on top of the film.
9. Carry the folder to the etching press.
10. Open the folder and lift out the plate by holding the overlap of film. Carefully slide the plate onto the sheet of acetate that has been placed on the bed of the press. This acetate sheet ensures that a smooth surface will imprint on the polymer film during lamination. Since the film is protected by the metal plate, no light is likely to touch the UV sensitive surface.
11. Now place another sheet of sturdy acetate (or the discarded Mylar) on top of the plate and lower the press blankets. This acetate will ensure an even transfer of pressure and safeguards against cutting the blankets.
12. The plate can now be run through the press twice or even three times under firm pressure to ensure a firm bond between plate and photopolymer film. Bear in mind that these materials are pressure sensitive so insufficient pressure may result in a badly laminated plate.
13. Slide the plate back into its folder and carry it back to the safe light area.
14. Trim off the excess film with a sharp blade and then heat the plate with a hairdryer or in a drying cabinet. The plate is now ready for exposure.
Troubleshooting in the lamination process
Most film should laminate without any problems if the above instructions are followed. On occasion, however, it may be necessary to modify this routine in order to resolve certain problems. If you find that areas of your plate are badly laminated – patches of film coming off/ creases/ bubbles – first check that these symptoms are not the result of insufficient sanding, degreasing or pressure. The manufacturers of photopolymer film also emphasise the importance of creating a slightly acidic surface on the substrate before laminating, so an acidic degreaser should always be used. In industry, photopolymer films are laminated wet under pressure and heat, so you can achieve good adhesion if these conditions are replicated. You may, for example, place the plate and film on a hot plate or in a hot cabinet before laminating them together. The film can also be softened by spraying it with warm de-ionised water before bringing it into contact with the prepared plate. To increase contact of film and plate it is also possible to run a roller over the surface before lamination.
The lamination method first recommended by Keith Howard involves spraying a water-alcohol mist onto the film before bringing it into contact with the plate. This mix can be made from two parts water + one part 70% isopropanol alcohol (ethanol alcohol would also work).
If your laminating is unsuccessful; check:
Have you sanded the plate sufficiently?
Have you degreased the plate sufficiently?
Did you use a slightly acidic degreaser?
Have you applied enough pressure?
Still having problems; then try the following:
Place the plate and film on a hot plate/ in a hot cabinet before lamination.
Spray the film with warm de-ionised water before contact with the plate.
Run a roller over the plate surface before lamination.
It also includes advice on testing the developer strength, making digital
With the latest generation of ImagOn, Keith Howard recommends a wet lamination process to give the best results. This method guarantees a smooth plate surface and prevents small imperfectionsthat can occur during dry lamination. Details are given in his comprehensive manual, The Contemporary Printmaker, including halftones for Intaglio Type and many more well researched pieces of technical advice.
For more information on equipment and facilities, go to The Acrylic Resist Etching Workshop.