There are many variations to how artists work with their processes, here Carol Hayman describes her process when working with photo intaglio plates – also called photo etching and photogravure.
My journey with polymer plates is a path along with the evolution of technology – the plates, transparencies, copy machines, PhotoShop, and digital cameras. The process is also called photo etching and photogravure. Real photogravure is a much more detailed and exacting process, which involves putting a photographic image on a copper plate, so I avoid that term.
“Photopolymer plates, associated processes, and materials have changed over the years I’ve been working with them. The basic aspects are the plates, the source of UV light, the transparency, and the image. Also necessary are printing papers and an intaglio or etching press.”
1The photo intaglio image
The first step is the image. Digital photography has changed the technology of photography so quickly in just a few years. Now everyone is a photographer. When I first started making photo intaglio prints, I was using film and slides for the first step. Drawings can work too. So now, I start off with a digital photograph in a computer and use Adobe Photoshop to change the image to black and white, adjust it to make nice contrasts in light and dark, then save the image at 300dpi in greyscale.
2nd step. The image has to be transferred to a transparency. Early on, I would take a photo to a copy machine and print the image onto an overhead projector transparency. Over time, copy machines changed, transparencies changed, manufacturers altered their products and each time this happened the process and timing would have to be altered too. The transparency might be too flimsy or opaque to UV light. The copy machine might not copy photographs well. Many times it is just serendipity as to how the final print will look. Recently, copy machines lost the ability to be able to print on transparencies, so now I send my black and white digital photographs to a commercial graphics company to print the image on a sturdy transparency.
3rd step is the plate. There are basically 2 kinds of polymer plates for sale to artists in the US. Both work well, but differently and come in different sizes and prices. One is available from Dan Welden who popularized solar plates and sells them in different sizes on his website solarplate.com. He also makes and sells UV light boxes for using with the plates, which is what I use. UV light from the sun is a good, but unreliable source of light for exposing polymer plates. You can figure out the timing for exposing a plate by making a timed step test plate. This is helpful in any kind of UV lighting situation. But how do you compensate for the minutes when a cloud floats over your plate during an exposure?
The other kind of polymer plate is made in Japan and sold through Takach Press in different sizes and 2 thicknesses https://shop.takachpress.com/category-s/1835.htm. They work basically the same way with slightly different exposure times. My preference is for their cheaper thinner plates, but they don’t make the nice impression in soft cotton paper that thicker plates make, so it is worth using thicker plates for tiny images.
4th step is the exposure. These polymer plates have to be exposed to Ultraviolet light. UV light can come from the sun or from a lightbox with UV bulbs (like for suntanning beds). Good results are not guaranteed! The time of exposure to the light is the critical element and the way to get a good estimate of timing with your personal setup is to make a test strip, necessary for the different kinds of UV light boxes available. Also critical is to make sure you have a good seal between your transparency and your plate, no air between, the transparency should have to be peeled off the plate afterward. My exposure involves a double exposure with first, a stochastic or aquatint screen, then the transparency. This creates a half-tone effect which allows the dark areas to capture and hold the ink in a print.
My set up is to make a layer cake of
- a nice flat board,
- soft, spongy shelf liner,
- the polymer plate,
- the aqua tint screen or the transparency with the image (doesn’t matter which is exposed first). Be sure the image is placed right side down so it will come out reversed on the plate and the right way around on the print. Next
- is a piece of heavy plate glass to exclude all the air bubbles, then
- the portable lightbox. For extra weight, I sit on the lightbox to make a good seal of the transparency to the plate. For sunlight exposure, use plastic clamps to squeeze the board, the rubber mat, the plate, the transparency or screen, and the plate glass together in a really tight sandwich. The plates cannot be exposed to sunlight, so avoid windows and skylights. For sun exposure, make the board/glass sandwich indoors and cover it with cardboard to protect it from the sun’s UV rays. Make sure there are no flecks of dirt, cat hair, or smudges on the plate or transparency.
Make a timed test strip to figure out exposure time. Set your timer for the maximum time for the sun, for Solar plates, or for Takach plates. Mark a test strip with time increments. Take your board/test plate/transparency/glass sandwich and lay your test strip next to it (or you can mark your test plate). Cover everything. Start your timer and remove your cover to expose the longest timed area of your strip, after the interval, move the cover to the next interval, repeat until the shortest time interval is exposed. (Practice away from your UV light source first!) This will give you a general sense of the correct timing for your plate, transparency, and light source.
Timings. Start with an approximate time range from 30 to 90 seconds for Solar plates, or 60 to 150 seconds for Takach plates, both kinds of plates can be exposed in a Dan Welden lightbox. For exposure in the sun, try 2 to 6 minutes. About 4 minutes works for me, the sun is really bright in Texas, even in winter. Remember to expose your plate twice, once with the aquatint screen, once with the transparency.
After exposure, cover the plate and away from UV light, unclamp it. Then wash it gently in a sink with room temperature tap water, lightly brushing away the unexposed parts of the polymer coating with a mushroom brush. Rinse and dry your plate with a paper towel and a hairdryer, then harden it in UV light (the sun or lightbox) for at least 10 minutes or longer. If it is still sticky, harden it for longer.
Areas that are underexposed because of a dark transparency or less UV light will wash away. Overexposed areas because of a thin transparency or more UV light will be too light. Another occasional problem is that sometimes really fresh plates might show up with tiny white dots of unknown origin on the finished plate, which can be solved on the next plate in the batch by brushing or blowing a very light coat of talc or cornstarch on the plate before exposure. This helps make the tight seal between the plate and the transparency.
5Print the image!
Use basic printing techniques with printing paper and printing ink. My preference was Faust ink, but now I use Charbonnel ink and Arches BFK RIVES French cotton paper. Also, I use chine collé with Japanese washi paper on various kinds of handmade paper. Some kinds of paper stick to polymer plates even after hardening, so use chine collé to prevent bits of paper from peeling off the print. Having tried and true favorites leaves out at least some of the many variables that can affect the end result. The printed image is also affected by the thickness or stickiness of the ink, wiping techniques, and press pressure.
The best way to get good results is to test and practice and not get discouraged by failures. Print several times in different colors and with additives for different textures of ink to see what works best for each plate.