Zaffron experimented with the use of Riston as an etching resist, (this use mirrors its intended industrial application for etching circuits into copper), but Howard went down a completely new route.
He realized that the film itself could provide a new kind of printmaking medium, if sandwiched onto a hard substrate.
'Non-etch' etching was born!
Traditional intaglio printmaking cannot produce the kind of full photographic color achieved in other print media. In the year 2000 Keith Howard and his colleague David Jay Reed set out to change that fact.
Through a new collaboration at the RIT printmaking lab, a number of Intaglio Type techniques were developed that bring photographic realism to the intaglio medium - in full, glorious color.
In a similar manner to screenprinting or offset, a set of primary colored plates is made from color separations and then overprinted, on the same sheet of paper, to produce the full spectrum of colors. The fact that these prints are made in the intaglio manner gives a tremendous richness and saturation to the resulting image.
The Decisive MomentThe Photopolymer Gravure Art and Photography of Henrik Bøegh
by Friedhard Kiekeben, 2018
The Danish artist Henrik Bøegh is known as one of the most prolific advocates for safer printmaking.
Susan Groce 'Invasive Species', Intaglio Type Assemblage, click to enlarge
A ground breaking new Printmaking Medium
adapted for artists from uses in
the Printed Circuit Board
and Electronics Industry.
note: some kinds of film may currently be unavailable (Howard/Zaffron films), but there are plenty of alternative sources | some of the industrial suppliers/manufatcurers include (PCB / electronics industry):
FULL LIST OF CURRENT SUPPLIERS OF
"...Photoresists are photosensitive materials which after photoimaging and subsequent processing, resist action of certain chemicals in desired areas. They are basically of two types. In negative photoresists, light-exposed areas become less soluble as a result of crosslinking or photopolymerization, leaving behind, after etching and stripping of the resist, opaque features on a clear background. On the other hand, in positive photoresists, the light-exposed areas become more soluble. The photoresists are available in liquid as well as dry film form. They may be solvent or aqueous developing types."
"Historically asphalt was used as a photosensitive resist material. In time, it was replaced by dichromated colloids including gelatin, casein etc. The first photoresist based on a photopolymer was invented by Eastman Kodak in late 1940s. This negative photoresist was based on a synthetic photopolymer, polyvinyl cinnamate, in a solvent solution. Crosslinked polymer was insoluble in solvents such as xylene and chlorohydrocarbons which were used as developers after UV exposure. Need for lower viscosity products led to development of negative resists based on cyclized polyisoprene. These photoresists were instrumental in the incredible growth of printed circuit industry and subsequently integrated circuits used in semiconductors."
"Pollution concerns led to development of dry film photoresists which grew out of DuPont’s work on photopolymer printing plates. Dry film photoresists are supplied as a sandwich of a photopolymer layer between a polyethylene film and a polyester film. Initially dry film types were solvent-developing but aqueous-processed film resists soon followed and are widely used today for manufacture of printed circuit boards. They are essentially based on acrylic chemistry. In secondary imaging of printed circuit boards, liquid photoimageable products based on epoxy chalcone or acrylated epoxy novolac are employed as solder resists. Cationic polymerized epoxies are employed in thick film resists especially for fabrication of microelectromechanical (MEMS) devices."
As already mentioned, there various kinds of dry Photopolymer film that also work for Photopolymer Printmaking; often these are adapted from their original use in the printed circuit board industry as etching resists. All film are sandwiched between two layers of clear mylar and expose with UV light, and all films develop in a soda ash developing solution. Developing times, exposure times, film thickness and contrast / tonal range may vary from product to product. The thick variants of film are ideal for non-etch printing, while the thin varieties are best suited as a photo etching resist (such as Puretch).
some product samples:
Photopolymerfilm, UK (Photec)
CapefearPress, US (Skylight)
Photopolymer Film vs Solarplate
Some print studios and artists prefer the use of ready made photopolymer plates from the printing industry over the use of dry film. The process is very straightforward as the user does not have to go through the plate making steps. The quality of the photo-reprographic intaglio prints made by these plates can be outstanding. This is due to the thickness of the polymer emulsion and the high tonal range and fine detail facilitated by these ready made plates, especially if used with a good aquatint screen or a high quality halftone. However, plates tend to be expensive, and creatively the process is somewhat more limited than dry film photopolymer printmaking. First pioneered by Eli Poinsang in Denmark, the method was popularized by Dan Welden with his Solarplate process. Click here for details. There are additional safety considerations that are advisable.
PHOTO POLYMER FILM, SOLARPLATE and SAFETY
Both processes are based on a fundamentally different polymer chemistry!
There are a number of factors and reasons
that suggest that dry photo polymer films from the electronics
industry may be a significantly safer product and process than
some of the ready-made flexography plates ('Solarplate' type plates).
Caution is advised.
Safety Aspects of Photopolymer Films and Plates
Handling Procedures for DuPont Photopolymer Films TB-9944
Handling Procedures for Photopolymer Films
(quotations from DuPont published information)
"Incidence of Health Effects: ‘Numerous operators worldwide have handled DuPont photopolymer films daily for forty years, but DuPont has received only a few enquiries per year on health effects. Although not every instance of related health effects is reported, the records show that few cases occur.'
Health effects of Acrylates. DuPont as well as other manufacturers formulate photopolymer films with multifunctional acrylate monomers. Historical and toxicological information has shown that that multifunctional acrylate monomers can produce potential health effects…Overexposure to the acrylates in the films can have these known effects: Respiratory irritation / Skin Irritation / Skin sensitization
‘Casual contact does not appear to cause monomers to be transferred to the skin and absorbed in sufficient quantities to cause skin irritation...’
Heating of photopolymer films generates vapors, and the condensate resulting from these vapors, is responsible for virtually all reported health effects. To prevent exposure, equipment that heats the film must have an exhaust system that will remove vapors from the workplace and avoid the formulation of vapor condensate. Inhaling vapors from heated film may result in dryness and irritation of the respiratory tract. This is especially true if films are heated above their normal use temperature. More harmful effects are possible if normal safety precautions (e.g. laminator ventilation) are totally disregarded."
ImagOn (HD) TM, DuPont - Special Instructions for Keith Howard's last generation of film;
many printmakers are still using this product, but suppliers are nearly out of stock
A Note about using ImagOnHD
ImagOnHD represents the latest generation of photopolymer film designed to yield higher definition due to its transparent green emulsion.
ImagOnHD functions a little differently to other, older ImagOn films. The instructions for using other ImagOn films outlined in "Non-Toxic Intaglio Printmaking" will not work properly for this new film. The most essential element for successful use of ImagOnHD is to follow the instructions in Keith Howard's manual, The Contemporary Printmaker. This new film has basically the same instructions as for ImagOn ULTRA rapid. Before commencing, it is very important to test your soda ash developer, as outlined in Keith's book. | With ImagOnHD the emulsion is no longer blue but transparent green. Always make an exposure test. To lighten an image INCREASE exposure. To darken DECREASE exposure. On industrial exposure units always choose the lowest intensity lamp setting or filter the lamp with neutral density filters (#210) from www.leefilters.com. Ideally the Aquatint Screen exposure should be around 20 seconds. This is extremely important for achieving optimum results. | ImagOnHD can also be dry laminated by removing the peel-back film layer: place the emulsion face up on to a sheet of pristine Plexiglas, then lay a plate on top and run through the press. Heat cure the plate as normal. ALWAYS mix ImagOn developer and LAMINATE the ImagOn to the plate the day before exposing and leave covered. | ImagOnHD has a transparent green color making it easy to register 4 color Inversion Intaglio-Type plates. This transparent quality of the plate makes upside down plate sequence printing easier. | ImagOnHD has the same developing process with a 9 minute still development in a 10gm soda ash to 1 liter of water solution BUT your image may benefit by an additional 1 minute gloved hand agitation using a soft dish-washing sponge. | The ImagOnHD plate is fixed with white vinegar and washed with water as with the old film. | Do not store the film in temperatures over 75 degrees F.
Click for the 'Grabado y Edicion' article Keith Howard: Llego la revolucion (2008)
Or visit the publication website: www.grabadoyedicion.com
Click for the 'Grabado y Edicion' article fotograbado con film fotopolimero (2008)
Or visit the publication website: www.grabadoyedicion.com