Highpoint Center for Printmaking – Polymergravure Workshop 2016

Over the past however-many-years I’ve been giving these workshops at Highpoint, they have always been 2 or 2.5 days long. This length of time is certainly enough to learn the process, but many of the participants wanted to continue and experiment and take the process further. This 8 week long workshop will give you more of an opportunity to work with the plates, discover the changes that can be made by using different inks, modifiers, papers etc. and to really discover the process.

 

The course is structured so the first four sessions will be devoted to learning the process and its many variables. The remaining sessions will give us time to work on the plates in depth, producing print editions and to work with new images, if you wish. It will also allow everyone to continue working at a pace that they’re comfortable with.

 

This is a beautiful, completely hands-on process and capable of giving results that can be so rewarding.

Session 1 – Tuesday October 27th

Introductions.
General overview of the process.
Look at and discuss polymergravure prints.
Familiarization of the Highpoint darkroom, studio and equipment.
Start making the digital film positives.

Session 2 – Tuesday October 4th

Continue making film positives, if necessary.
Outline of the platemaking process.
Finding the optimum screen and image exposures via separate step tests.
Start exposing and processing plates.

Session 3 – Saturday October 8th

Continue platemaking, if necessary.
Discuss how to control contrast by varying the screen and image exposures.

Session 4 – Tuesday October 11th

Modifying inks, paper preparation, inking and wiping the plates.
Start proofing the plates.

Session 5 – Tuesday October 18th

Studio time.
Platemaking and printing as necessary.

Session 6 – Saturday October 22nd

Studio time.
Platemaking and printing as necessary.

Session 7 – Tuesday October 25th

Studio time.
Platemaking and printing as necessary.

Session 8 – Tuesday November 1st

Studio time.
Platemaking and printing as necessary.

PLATEMAKING WORKFLOW

The polymer photogravure process has gained popularity over the past few years with photographers as a more affordable and environmentally-friendly process compared to the traditional copperplate intaglio method. No toxic chemistry, less space required and speed are some of the many advantages.

 

It’s a contact process requiring a film positive the same size as the final print. In the past this meant having access to a darkroom and working with large format film and chemistry, but now this step is easily accomplished using an inkjet printer.

 

The polymer plates are very slow in speed and only sensitive to ultraviolet and fluorescent light, so the work can be carried out in low level tungsten or incandescent lighting. Another advantage – yellow or red safe lighting is unnecessary.

 

The plate is exposed twice to UV light, once in contact with an aquatint screen and then again with the image film positive. Afterwards it’s processed in water for several minutes, dried and hardened by exposing it once more to UV light. The plate can then be inked, wiped and printed as with any intaglio plate.

 

One of the most important requirements of this process is complete contact between film and plate, as any uneven contact will result in problematic plates. This is usually the biggest hurdle for anyone working with this process. The only way that complete contact can be made, especially for larger plates, is with a vacuum frame and replacing the glass with a plastic material called Kreene. This material is a soft, semi-opaque plastic that is used in making polymer plates for letterpress printing.

 

 

MATERIALS

Pictorico TPU100 film. This is the substrate used for making the film positives.

Polymer plates. Toyobo Printight KM73.

Aquatint screen. Film with a stochastic, or random patterned screen. This replaces the dust grain step in intaglio and breaks the image into minuscule ‘dots’.

Paint pad. Used to gently washout the polymer plate.

Kutrimmer – or a utility knife, a straight edge and LOTS of care.

 

 

PLATES

There are many different brands of polymer plate with a wide variety of polymer thickness, hardness etc. The one that I’ve settled on and that has given me consistent results over the past 16+ years has been the Toyobo Printight KM73 plate. It has a resolution and hardness that’s perfectly suited for intaglio and photographs.

 

The nicest and easiest company to order these from online is Boxcar Press, a company that started in south Minneapolis but who are now based in Syracuse, NY. They omit the Toyobo Printight name on their website but they are the same steel-backed KM73 plates.

 

 

CUTTING THE PLATE TO SIZE

The plates consist of a UV light sensitive polymer layer bonded to a metal base with a protective Mylar cover sheet covering the polymer.

 

Although the metal base is fairly thin, cutting the plates cleanly is one of the most important steps in the process. Any rough edges or bending of the plate during this step will affect the contact between the film and plate and will show in the final print. It will also affect the exposure, which in turn will lead to inconsistent results between tests. The perfect plate has a clean cut edge and is perfectly flat.

 

The easiest method is with a Kutrimmer. This guillotine ensure the edges are cut clean and without burrs. It is possible to use a utility knife and a metal straight edge and repeatedly score the plate until it snaps easily, but care has to be taken to ensure a clean break and to avoid any bending of the plate.

 

If the image is to have a border and a plate mark, then the plate can be cut once, approximately 1/8” – 1/4” larger than the image size. If no border is required and the image is to bleed to the edges of the plate then it’s best to work with a plate size slightly larger than the film to ensure good contact and then cut the plate with a Kutrimmer to the final size AFTER processing but before hardening.

 

 

EXPOSING THE PLATE

Remove the protective plastic sheet slowly and carefully. At this stage the polymer is soft and easily damaged. The smallest of marks WILL show.

 

Carefully brush the aquatint screen free of dust and place emulsion side down (dull side in contact with the polymer) onto the plate. Place this sandwich into the frame being careful not to move the screen and close the frame. Expose for the pre-determined screen exposure.

 

Remove the aquatint screen and repeat these steps using the image positive and make the second exposure.

Remove the plate from the frame and carefully put aside the film. The steel back of the plate can be marked with a Sharpie indicating exposure and processing time.

 

 

PLATE WASHOUT

Fill a tray with approximately 2 litres of water at 70 o – the exact amount isn’t critical but the temperature is.

 

Place the plate polymer side up into the water and gently brush with a paint pad or sponge for 2-3 minutes over the entire area of the tray. The aim is to gently wash away the soluble polymer – no great force is needed to achieve this.

 

The area ‘scrubbed’ during washout is always the full size of the tray, even though there may just be a small plate in the middle. This way, it doesn’t matter what size the plate, it always has the same amount of agitation per square inch.

 

When the time is up, remove the plate and immediately dry it by placing several sheets of dry newsprint on the surface of the plate and gently wiping a hand over the paper. Be careful not to move the paper which can damage the soft polymer. This step should only take about 10 seconds.

 

Quickly and carefully remove the paper and start drying with a hairdryer set on low heat. A film drying cabinet is perfect too, if available. Dry the plate for a further 5-10 minutes.

 

If no border or plate mark is required and the image is to cover the entire plate, now is the time to carefully cut it to size. The polymer is still quite fragile and soft and care is needed not to pick up dust and scratches.

 

 

POST-EXPOSURE HARDENING

Once the plate is completely dry it has to be hardened and cured to withstand the pressure of the press. This is done by re-exposing the plate to UV light without the contact frame, film or screen. This exposure time is not critical, but should at least be as long as the original screen and image positive exposures combined.

 

 

DETERMINING THE SCREEN EXPOSURE

The first step is to determine the amount of exposure necessary to give a good black without resulting in areas of open bite or becoming too light and grey.

 

Simply expose and process a small plate in contact with just the aquatint screen. During washout some areas will wash away completely (resulting in open bite) while others will be overexposed and produce lifeless grey areas. Somewhere between these two extremes will be a series of steps that, when printed, will give a good black. Choose the step just beyond the area of open bite – this is the screen exposure that will safely produce deep blacks without being washed away. This screen exposure will remain constant between plates regardless of the image and need only be retested when using a new batch of plates.

 

It’s also possible to control the overall look of an image by varying the two exposures. Screen exposure controls the blacks and the shadows, while the image positive controls the whites and the lighter tones.

 

 

DETERMINING THE IMAGE EXPOSURE

Expose a plate to the screen using the exposure time determined above.

 

Remove the screen and place the image positive on the plate. Expose the plate in a series of steps of varying exposures.

 

Remove the film from the plate, process and harden as normal.

 

Print this plate and determine the best exposure for the image. If the shadow areas are too dense and too black, the screen exposure can be increased slightly and the image exposure reduced to soften the shadows.

 

 

FINISHING

At this point the corners can be rounded using a file and the edges made smooth with a sanding block. The aim is to obtain smooth edges that are not only safer to work with but won’t hold ink. The edges of polymer plates can be a lot harder to keep clean and wipe free of ink than copper plates and ink can sometimes creep between the polymer and the steel and only become noticeable in the final print.