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| Photopolymer
plates, or Solar plates as they are also known, are
used in the Flexographic printing industry and 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 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, Enameling and
general textures & designs.
I use steel plates for anything that needs very clean
lines, and plastic plates where the design is less demanding
of perfection, such as master plates for carving, where
a lot of work is done to the clay after impressing.
And, sometimes, very sharp clean lines are not part
of the design |
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Solar plates are made up of 3 layers:
1. A Steel or Plastic backing plate.
2. The light sensitive polymer layer that will form
the impression. This is the layer that hardens where
it is exposed to UV light.
3. A cover film. This protects the plate and is removed
before exposure.
The overhead transparency artwork
is placed on the plate. The black areas in the artwork
block out the UV light and the plate underneath will
remain soft, they are later washed away. The clear areas
will let U.V. light through and will harden the plate
below. |
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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 you use is no thinner
than 1 pt (= 0.5mm - 0.02") or 2 pt (= 1 mm - 0.04")for
deeper impressions.
- Any picture could have potential; try playing around
with a photocopier, changing contrast settings.
- 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. I have not tried these
myself, so I can't comment on their suitability. Try
it and see! |
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Light
Sources
| Sunlight;
not easily controlled, even an hour from the time you
started, you could need a different exposure time. Test
strips are vital here. |
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Halogen desk lamp
(50 watt);
Long and hot exposure, the
one I've used takes 7 minutes and gets quiet warm in
that time. Heat is a problem with Photopolymer plates,
try to avoid it if you can.
UV Fluorescent tubes;
These are the best exposure
lights, 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. |
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UV lights can be bought at any good electrical
store. Check out lapidary supplies too, they use UV light
and have a range of models available. Here is one I use
when traveling. It is a plastic armature that is sold
for use in caravans & trailers. I have just replaced
the tube that was in it with a UV one. The sides lift
the light 10 cm (4") from the plate surface, it attaches
with Velcro and is easily dismantled. |
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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.
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. You'll also
need 4 bulldog clips. |
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
- 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.
- Cover the plate with some heavy card for all
of its length except the number 1's on the artwork.
Set your timer for 20 seconds, switch on your
UV light source and expose for that length of
time.
- Switch off the light, reset the timer for
another 20 seconds, move the cardboard to 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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Here
are some things to look out for when 'reading'
the test results:
" If the washed out line
looks wider than it should, too much has washed
away,
this means the plate is under exposed. A longer
exposure time is needed.
" No or a shallow image
after washing out; the image is over exposed.
This can happen because:
The exposure was too long. - cut down the exposure
time
Transparency not solid black - double it up
if transparency is not solid black (check by
looking
through to light)
Plate was left out in UV light rendering the
plate fully exposed - keep unexposed plates
wrapped up
in light tight material, such as black plastic,
especially near UV light.
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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.
Polymer
layer is cracking or lifting off:
The plate has been exposed to too much heat,
* either 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. |
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A
guide to sizes of plates
These are the three 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.
Medium Steel Based 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.
Some PMC suppliers are now also stocking plates.
Box Car Press:
http://www.boxcarpress.com/cgi-bin/shop.pl/page=polymer.htm
Photopolymer Plates by Gene
Becker:
http://www.photopolymerplates.com.
Whole lot of Whimsy
http://www.wholelottawhimsy.com |
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