For the first time, a high quality positive photo emulsion coating on a conventional deep etch ball grained plate is being produced specifically for printmakers using direct litho presses. Posi-Grain plates are manufactured by Precision Ballgraining Corporation and were developed in collaboration with Dwight Pogue and Mark Zunino, printmakers at Smith College, Northampton, Massachusetts.
- Uses:
- To expose graphite and wash drawings made on mylar as well as halftone films and computer-generated "dither" random dot patterns on clear films.
- To add hand drawn imagery to a photo plate that has already been exposed and developed. The plate is then processed and rolled up like a regular ball-grained plate. The process is capable of retaining minute detail.
- To produce reduction exposures. A single Posi-Grain plate can easily be exposed and printed multiple times in a reduction manner, permitting two or more images/colors to be printed from one plate.
- To transfer a 'key' outline or ghost drawing/image to multiple plates - one for each color - which can then be hand-drawn using traditional lithographic drawing materials.
History of Posi-Grain Plates
Dwight Pogue © December 30, 2000
I first began making lithographs using photo plates (wipe-on negative emulsion on ball grained plates) in 1970. I was encouraged when one of the prints was accepted to Graphics 71, a national print exhibition in Silver City, New Mexico. By 1974, I was making four-color separation prints, one of which was in the l976 Fifth British International Print Biennale. At that time I was using Hawson Algraphy "Olympic Gold" positive working plates. However, by the late seventies, I was back to hand drawing on uncoated deep etch ball grained plates, using an average of eight or more plates for an edition of lithographs. Occasionally, I included one or two positive plates for quick areas of color.
I always felt the ideal plate for artists/printmakers would be a positive coated deep etch ball grained plate because hand drawing could be added after development and it would be easier to print using a direct lithographic press. In 1994, I introduced a two-week computer component to my traditional lithography courses. Students were exposing random dither dot images onto smooth, commercial positive photo plates. I was not happy with the results and soon became interested in finding a way to combine hand drawing with computer images on the same plate. Since it is easy to add new hand drawing to deep etch ball grained plates and to print them on direct litho presses, the solution was to develop a high quality positive photo emulsion coating that could be applied to a conventional deep etch ball grained plate. When the opportunity to develop such a plate finally arrived, thanks to Jim and Michael Hogan of Precision Ballgraining Corporation, I asked my colleague, Mark Zunino, and Jim and Michael to join me in conducting research to perfect it. What I guessed might take three months to accomplish took almost three years. In the spring of 1997, Michael produced several six-inch square samples for trial. Mark and I began making tests. Then the four of us experimented with different emulsions and different methods of coating plates to achieve optimum exposure times for delicate washes and drawings. Refinements were made over a period of months, and further trials eventually led to better-than-expected results.
Together with Precision Ball Graining Corporation, we introduced Posi-Grain plates for the first time at the March 1999 Southern Graphics Council Conference in Tempe, Arizona. After researching Posi-Grain's capability for multiple reduction exposures/printing, Mark and I conducted a demonstration at Tamarind Institute, Albuquerque, New Mexico, in April 2000.
How to Use Posi-Grain Plates
Dwight Pogue, ©March 2000
HANDLING: Prior to and during exposure and development, handle
the plates in yellow light. A yellow incandescent 'bug' light or yellow
plastic sleeves that slip over fluorescent tubes will protect the plates
from being exposed.
EXPOSURE UNIT: Although it is possible to construct a workable plate
exposure unit with a light source, sheet of glass and a pad of foam
rubber, it is not recommended if you want to achieve high quality results.
It is often possible to locate a good used plate-maker such as a flip
top Nu-Arc brand. Plate-makers should have a suitable light source and
tight vacuum glass frame capable of producing approximately 20 pounds
(sq. inch) or more of pressure. The "sensitizers" used in positive photo
emulsion coatings have a range of 350-420 NanoMeters. Therefore, the
ideal light source is a metal halide diazo bulb. Another bulb that will
work is a pulse zenon diazo bulb. The zenon however, does not produce
as even a light as does the metal halide bulb. Check the plate-maker
to determine the type of bulb it uses.
EXPOSING THE IMAGE:
To determine the optimum exposure for your unit, use either the free
test strip provided in each package of plates, or cut several two-by-ten-inch
test strips of plate from a full Posi-Grain plate and expose them for
different lengths of time. During the early stages of researching these
plates, one of our criteria was to provide an emulsion which would allow
a wider range of acceptable exposure times than most commercial photo
plates. Posi-Grain plates are therefore able to hold a wider range of
delicate articulated washes and generally require longer exposures than
commercial positive plates.
Unless bleeding the image off the plate, I always "double burn" plates
in order to obtain perfectly clean border/non-image areas. This is particularly
desirable when exposing images on multiple plates such as four-color
separations. The double burn will create a perfect image edge regardless
of how many colors are printed because the same single border mask is
used for all the exposures. The key to successful double burns is to
align everything to the same two pins on your registration system.
Once you have multiple images perfectly registered on each plate, it
is easier to set up a "T" registration system on your direct press.
DEVELOPING:
To develop the strips and, ultimately, the full-sized plates, use a
soft (photo type) sponge and rubber gloves, moving the PG-Developer
rapidly in a circular motion (light pressure) repeatedly over the entire
plate. Add fresh developer if necessary. (I prefer putting developer
on twice - each time thoroughly rubbing it lightly but rapidly). Rinse
plate thoroughly with cool water. The plate may then be rolled up in
ink and printed, rolled up in ink and counteretched for adding new drawing,
or it may be simply gummed and stored without rolling up. If for any
reason the plate image should not receive ink readily, simply pour a
small pool of PG-Cleaner on it and rub with cotton until dry. Wash off
with water and roll up. For storage after developing, we recommend that
you remove the excess water from the plate with a gum sponge, then gum
the plate with regular 14 degree baum gum arabic (we recommend GA-100).
Buff lightly with cheesecloth - not a tight buff as for non-photo plates.
Store the plate in a dark, cool area. Remember to keep the plate covered
with black paper when in the open (I place a sheet of black paper over
the plate even at the press when I'm not actually printing).
PRINTING THE IMAGE:
Rinse plate with clean water, remove excess and roll up. If the image
should not receive ink readily, simply clean it with PG-Cleaner. As
a matter of course, I prefer pouring a small pool of PG-C on the image
and rubbing it with cotton to remove the old gum and thus clean the
plate. Buff lightly with fresh cotton and fan with a hand fan. The plate
is now ready to be washed with fresh, cool water, rolled up and printed.
ADDING NEW DRAWING: If you want to add new drawing to the developed
image, roll the image up using black ink such as Daniel Smith Velvet,
Classic Black, or Senefelder's Crayon Black. Use either a leather or
composition roller. When fully inked, remove any roller marks, tint
or scum using a Scrunge sponge (foam rubber). Apply a counteretch solution,
wiping it with cotton carefully and lightly. Immediately rinse with
water, remove the excess with a sponge, apply more counteretch and repeat
the process. After two or three counteretch applications, rinse the
plate with water and blot carefully, then fan dry immediately.
The plate is now ready for new work. Although all litho pencils work
well, we prefer Stones Crayons. Counter Etch Solutions: (either works
well) (1). One gallon of water, one ounce of Phosphoric Acid and one
ounce of Hydrochloric Acid. (2). One quarter teaspoon of Anhydrous Citric
Acid crystals to ten ounces of water.
ADDING WASHES TO A ROLLED UP IMAGE:
Tusche washes made with water rather than solvent-based washes are recommended
since some solvents can alter or dissolve the photo emulsion. Toner
washes may be used if made with distilled water and small amounts of
Photo-Flo or liquid soap.
The Art Department at Arizona State University (Tempe) uses a Ricoh
Toner type recipe which works very well:
1 teaspoon of Ricoh Toner type 6080,
2 ounces of distilled water and 10 drops of Photo-Flo.
Once dry, toner washes must be 'set' or attached to the plate prior
to applying the first gum etch. One ideal method for setting the toner
wash is to allow only the vapors of the naptha to reach the plate. Construct
a simple lightweight plywood lid and place several inches of cotton
in it. Fit a wire screen over the cotton to secure it to the inside
of the lid or box.
To avoid breathing toxic fumes, do the following process outdoors
or use a ventilated hood.
Using rubber gloves, pour naptha (white gas) onto the cotton. Immediately
place the plate face down (with the image directly over the cotton)
on the lid and allow the vapor to 'set' the toner washes. If preferred,
the lid may be placed over the plate as the vapors will still set the
toner. Test to ensure that the toner wash is attached to the plate by
lightly touching a small area of the wash. If the toner comes off, it
needs another application of naptha fumes.
After new work is added, process the plate as you would any regular
ball grained litho plate: talc, gum and buff tightly.
Take plate to a well ventilated hood area and wash out the image thoroughly
with lithotine and then lacquer thinner (wearing gloves of course).
Glaze cleaner may be used as a final wipe to super clean the plate,
however it is not necessary in most instances. Apply red lacquer V with
cotton and then buff rapidly with a fresh, dry cotton pad. Dry with
a hair dryer on hot heat for 3 minutes. Apply asphaltum and store or
roll up and second etch.
To roll up, wash the plate with water and roll up with black ink and
a leather roller. Once fully inked, clean any roller marks and tints
with a scrunge sponge or foam rubber and dry the plate. Any small, isolated
unwanted spots in the borders may be removed with lacquer thinner and
cotton in a well-ventilated area, or with Image Remover and a brush.
Talc, gum and buff. Generally, I prefer straight gum for the first etch
(after adding the new drawing) and tannic gum for the second etch (after
rolling up in ink).
PRINTING:
Printing the Posi-Grain on a direct litho press is the same as printing
any medium ball grained lithography plate. Tamarind Institute recently
published (1999) a manual on printing ball grained plates on direct
presses. It may be ordered from their web site, www.unm.edu/~tamarind.
Emulsion Reduction Process
During October of 1999, Mark Zunino and I discovered that
a Posi-Grain plate could easily be exposed and printed multiple times
in a reduction manner. This opens up new ways of working for the artist-printmaker
by allowing two or more images to be printed in different colors from
the same plate. The only condition is that exposure of the plate to
bright light during handling and printing must be limited. We keep the
plate covered with a black sheet of opaque paper until washing out and
rolling up in ink. When rolling up and printing, it is advisable to
work in somewhat subdued light. The plates are not sensitive to yellow
light, therefore yellow ' bug' lights or yellow sleeves placed over
fluorescent lights are ideal when using this plate.
Working Procedure
Mark Zunino, ©March 2001
As long as emulsion is still present on the Posi-Grain plate,
it may be re-exposed and re-printed multiple times. A good analogy is
reduction relief printing, in which the first state involves cutting
out only the whites and printing the rest of the block in a pale/transparent
color. Each successive state is printed gradually darker, and later
cuts reveal the lighter colors that were printed previously. The emulsion
of a Posi-Grain plate acts as the relief surface, and may be gradually
reduced and printed between exposures. New imagery will appear only
where there is still emulsion, so artists must adjust their imagery
accordingly. It is possible to print five colors from one plate, and
registration issues are simplified since the drawings for each state
are registered before exposure.
There are many variations, but the following may be used as a guide
for this process. ·
Make the images on clear acetate, or frosted mylar sheets. Although
any opaque drawing material can be used, we prefer Xerox Toner 6R84
mixed with Ethyl Alcohol, and Future Floor Wax, or Ruby Lith for flats
(more floor wax will result in flatter washes, more alcohol will result
in more reticulated washes). The floor wax serves to fix the toner to
the mylar. Note on exposure times: if the light source on your exposure
unit is strong, it is possible to overexpose the plate during multiple
exposures. Therefore, underexpose the initial states that are printed
in light ink, then expose later states at desired length. It may also
be necessary to cut the developer in half with water in order to avoid
over development.
For the first drawing, make a dense, almost flat black image leaving
the desired white areas open. Using registration pins and a hole punched
plate to line up the image, expose the Posi-Grain plate following the
instructions given, and print the image in light ink. Be sure to keep
the plate covered, or in as dark an environment as possible, until ink
is applied to the plate; otherwise, the emulsion will continue to expose
and the plate will not be able to accept additional exposures. ·
To register the second and subsequent images, hole punch mylars in relation
to the first mylar. Use opaque drawing materials such as graphite, Xerox
toner washes, etc, to create drawings that gradually become lighter
and more open. Print these states in gradually darker values.
Note: new imagery will appear only where emulsion still remains.
An advantage of working with mylar and the hole punch registration system
is that you can use a light table to help register the different states
of the image. · Once the emulsion is completely removed, or at any time
during the production of the print, the Posi-Grain plate can be changed
from an emulsion-based plate to a lacquer-based plate, counteretched,
and drawn into to use for additive, subsequent states.
Duotone Variation on Emulsion Reduction Technique
For a richer single image involving a wide variety of grays and tonal
variations use one plate to create a duo-tone print. For the first state,
underexpose the image and print it in transparent black ink. This will
ensure that all light values will be present. Once printed, put the
positive image on the same plate and overexpose it until only the darkest
values remain; print it in a darker version of the first black. This
process works well with graphite, computer imagery, and washes. It may
be necessary to try several different test strips to achieve the optimum
exposure time for each state.
For further information or technical assistance, contact
Dwight W. Pogue
Art Department, Smith College,
Northampton, Massachusetts, 0l063
or Dpogue@smith.edu
Posi-Grain plates and Developer may be ordered from:
CS Pogue Graphics
215 Linseed Road
Hatfield, Ma. 0l088 Ph: (413) 247-9221
Fax: (413) 247-9899
cspogue@mediaone.net
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Last updated: May 18, 2001.