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Butterfly Wing
made with a Solar plate
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| Photopolymer
plates, or Solar plates as they are also known, are
used in the Flexographic printing industry. They have
also been used by Artist Printmakers for many years.
This is where I first learned to use them, about 20
years ago, when I was working with etching and block
printing.
Making the plates is easy
and can be done in the home, no harmful or dangerous
chemicals are needed and the equipment used is easily
and cheaply obtained.
Plates are available on steel,
or plastic backing material and in different thicknesses,
making them suitable for a number of processes, such
as Keum-Boo, Enamelling and general textures & designs.
I like to use steel
plates for anything that needs fine, clean lines, and
plastic plates where the design is less demanding, such
as master plates for carving, where a lot of work is
done to the clay after impressing, or some of my enamel
designs, where the lines are thick and bold.
And, sometimes, where very sharp, clean lines, would
not be appropriate for the design.
So here's a description of the process, the way I’ve
been doing it, I hope it'll be helpful.
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Solar plates are made up of 3 layers:
1- A steel or plastic backing plate.
- The light sensitive polymer layer that will form the
impression. This is the layer that hardens where it
is exposed to UV light.
- A cover film. This protects the plate and is removed
before exposure.
Here's a brief overview of the process:
1. Remove the cover film.
2. The artwork, on overhead transparency film, is placed
on top of the plate. During exposure, the black areas
in the artwork block out the UV light and the plate
underneath will remain soft, the clear areas will let
U.V. light through and will harden the plate below.
3. Scrub the plate in warm water washes away the soft
parts of the plate.
4. Dry the plate and post-expose.
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Drawing
If you have the ability to draw, use pen & ink for
your designs.
Strong black & white is required, this is known
as 'line art' in the printing industry. You can also
draw in pencil and have the resulting drawing photocopied
to make a high contrast drawing.
Computer:
If you are proficient on the computer, using a graphics
program, you could scan a drawing and convert to a
high contrast drawing. Or if you want to do the complete
artwork in a drawing program like Adobe Illustrator
or Corel Draw, make sure the line width you use is
no thinner than 1 pt (= 0.5mm - 0.02") or 2 pt
(= 1 mm - 0.04")for deeper impressions.
Other design sources:
- Any picture has potential; try playing around with
a photo on a photocopier, changing contrast settings,
multiple passes through the machine will give different
results.
- Look at found textures, which could include maps
& charts, newspapers, letters, wing dings.
- There is also a lot of copyright free art available
for artists, look at 'Dover' books and crafter's motif
sheets.
All these methods are indirect; they
have to be transferred to an overhead transparency
(OH) before they can be used to make a plate.
You can do this by printing your design onto OH Transparency
material using a laser printer through your computer,
or get a copy centre to make a laser copy for you.
Check that the image on the OH transparency is nice
and black, not grey and partially see-through. You
can also draw onto the OH Transparency directly, using
permanent markers, or pen & film ink. Make sure
the markers are for use on film and very black so
no light can seep through.
Another possibility is direct exposing
materials onto the plates, with no artwork being done.
As long as the materials do not damage the light sensitive
layer of the plate and are sufficiently solid to block
out the light, they should work fine. Think of paper
cut-outs, maybe skeletonised leaves etc.
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Light Sources
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Sunlight:
Not easily controlled, even half an hour from the time
you started you could need a different exposure time.
Test strips are vital here, at least to start, you develop
a sense of timing after doing this a while.
Halogen desk lamp (50 watt);
Long (and hot) exposure, the light I've used takes 7
minutes and gets very warm in that time. Heat is a problem
with Photopolymer plates, I don’t reccommend them.
UV Fluorescent tubes;
These are the best exposure lights and in my opinion
the only ones to use. They are available from most lighting
shops. Use as many tubes together to suit the work you
do. With multiple tubes, space them as close as possible,
for even light, and to avoid 'hot spots'.
Have your light source about 4" (10 cm) above the
plate's surface, keep this as a constant.
The tubes I use are the white ones, not the black, white
tubes still produce 'black light'.
Black tubes produce heat and are
also a different UV rating. They work okay for PPPs
though, just not the best choice.
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UV lights can be bought (or ordered) at
any good electrical store. Check out lapidary supplies
too, they use UV lights and have a range of models available.
Some of the PMC suppliers have very nice exposure units
for sale, check them out, I’ve included some addresses
at the end.
Here is the one I use when traveling. It is a plastic
light fixture that is sold for use in caravans &
trailers. I replaced the tube that came with the light
with a UV tube.
The plywood sides lift the light 10 cm (4") from
the plate surface, it attaches with Velcro and is easily
dismantled.
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Cutting the plates
A plastic backed
plate can be cut with heavy duty household scissors.
Steel plates can be cut with metal shears.
Invest in a good pair of shears, they'll save you a
lot of trouble when you use them, as well as saving
your hands.
I bought some cheap Bench Shears,
they make very light work of cutting the plates, and,
they also cut my copper and silver sheet.
The draw knife. Make many cuts along a steel ruler,
the plate will then just snap off. This method is much
harder to use than the metal shears, but will work in
a pinch.
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The Exposure frame
A
simple piece of thin MDF board for the backing, a piece
of foam or bubble wrap to even out the pressure, and
a piece of glass the same size as your backing board,
make up the frame.
Buying a small, inexpensive photo frame
will give you the glass and backing board, check that
the backing is wood board, a lot of photoframes are
backed with stiff cardboard theses days.
You'll also need 4 bulldog clips.
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The Test Strip
This is the test strip I use now,
it has numbers to allow me to see where
the 1st, 2nd, 3rd etc. exposures were.
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Plates
can be handled safely in any non-UV light, fluorescent
tubes are fine. Just keep them out of sunlight
or have them near any UV light source.
Please note the exposure times mentioned are a
guide only, you might have to do the test strip
2 - 3 times to get the optimum exposure for your
light source. The times given, are for UV Tubes,
if you are using a 50W Halogen light, use 1 minute
increments ISO 20 seconds per exposure.
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Determining exposure
times by making a test strip
1. Cut a strip off the plate to the size of
your test strip. Remove the cover film from
the plate and position your artwork on the
plate, with the printed side touching the
plate. Position the plate in the centre of
your exposure frame, cover with the glass
sheet and position the bulldog clips so they
keep away from the design itself.
2. Cover the plate with some heavy card for
all of its length except the number 1's on
the artwork.
3. Set your timer for 20 seconds, switch on
your UV light source and expose for that length
of time.
4. Switch off the light, reset the timer for
another 20 seconds, move the cardboard to
uncover the number 2's and expose again.
Keep on doing
this until the whole strip has been exposed.
The very last exposure will have only received
20 seconds of light, the next 40 seconds etc.
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MAKING
THE PLATE
- Prepare your artwork
on Overhead projection film.
- Cut the Photopolymer
plate.
- Remove the cover film
from the plate surface. These cover films could contain
small amounts of polymer residue and should be discarded.
- Place the OH transparency
artwork on the plate and into the exposure frame,
clamped securely with bulldog clips. You are now ready
to expose the plate, using the time determined from
the test strip exposure.
- Wash out the plate
in hand-warm water, gently scrubbing with a natural
bristle brush, in a circular motion. If you want a
shallow depth wash out, like for Keum- boo, use a
natural sponge and keep checking your plate for depth.
For a deep washout, keep brushing until you can feel
clean base material, any photopolymer left on the
base will feel a bit slippery. If you are using very
thin lines it might be better to wash out leaving
a little bit of material on the base to reinforce
the line. Thin lines have a tendency to lift off.
- Wipe excess water
off the plate with the natural sponge and dry the
plate surface in front of a fan heater set on medium,
with the plate on its edge about 30cm (1') away from
the heater for about 5 minutes. The plate should feel
totally dry with no stickiness.
- Post expose the plate
for the same amount of time you used for the initial
exposure. This will harden the plate all the way through.
Brush a little vegetable oil over the whole plate,
this stops it from drying out and cracking. Store
finished plates in a plastic bag, to exclude moisture.
- To use with metal
clay: brush on vegetable oil, with very fine, or deep
detail, a smear of Badger Balm on the rolled out clay
helps releasing the clay from the plate.
- For use with polymer
clay: use corn flour (cornstarch) or just plain water.
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Finished plate ready for use
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Washing - out
Use lukewarm water and a soft bristle
brush for washing out the plates. A foaming action will
be apparent where the polymer washes out. Don't wash
out too long, 2-3 minutes should be enough, to avoid
the risk of the polymer lifting off the background material.
Take care not to scrub the plate too hard. Wipe excess
water off the plate and dry with a lint free paper towel
or chamois.
Dry the plate completely with a hairdryer
or fan heater, do not allow the plate to get too hot
while doing this, the polymer layer could crack or lift
off the backing material. |
Lack of detail
in the image:
Contact between transparency & plate not
tight enough.
Make sure to use an exposure frame to keep
the film tight on the plate during exposure.
Washed
out line is too wide:
Image was under-exposed, not enough material
is hardened and washes away.
Expose a test strip to determine the correct
exposure time.
Lines
will not wash out deep enough:
Image is over exposed, or the transparency was
not black enough to block out all the UV light.
If the image looks black when held up to
the light it should be fine, otherwise double
it up. If image was okay, do a test strip exposure
to determine the correct exposure time
Polymer layer is
cracking or lifting off:
The plate has been exposed to too much heat,
- At exposure - raise the light, keep exposure
time as short as possible under a hot lamp.
- When drying after wash-out - Keep the dryer
on medium or low, or keep a close eye on the
plate when drying in the sun.
Plastic Plates
are curling:
The plate has dried out too much.
A quick dip in warm water, then let the plate
absorb it for a minute, dry and post expose
for the same length of time as when you first
made the plate.
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A
guide to sizes of plates
These are the four main sizes I use:
Medium Plastic Based
Plates 1.14 mm ( 0.04")
This is a useful size to have, it works well for low
relief text & patterns and all general texture plate
making. It can be washed out to a shallow depth only
and used for Keum-boo. Cut with heavy duty household
scissors.
Thin Steel Backed Plate 0.8 mm (0.03")
This very thin plate is great for Keum-boo textures,
where you don't want a lot of depth to the texture.
Medium Steel Backed Plate
1.5 mm ( 0.06")
The emulsion of these plates is a little harder, they
make a crisper image than the plastic backed plates,
making it especially suitable for lettering and images
that must have very sharp detail. Cut with metal shears,
bench shears or guillotine.
Thick Plastic or Steel Based
Plate 1.75 mm ( 0.07")
Available in plastic or steel base, these make a very
deep impression, but it can be a little harder to get
PMC out of small details. This plate is very useful
for Champlevé enamelling and lettering where
a higher relief is required.
My
thanks to South Australian, Dianne Longley. Her
book Printmaking with Photopolymer Plates was
invaluable to me when I initially learned about
the plates, and again while preparing this presentation.
This book is still available. To order, go to
Dianne's
web site: and download the PDF order form |
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Suppliers
This is just a starting point, there are many suppliers
to the printing trade,
check your local Yellow Pages.
Most PMC suppliers are now also stocking plates, here
are a few of them:
Whole
lot of Whimsy
http://www.wholelottawhimsy.com/
Cool Tools
http://www.cooltools.us/
Artclay World
http://www.artclayworld.com
Box Car Press
http://www.boxcarpress.com/
Photopolymer Plates by Gene Becker
http://www.photopolymerplates.com./
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