PHOTO ETCHING INSTRUCTIONS
			Edith Smith, Instructor

I. Cut photo-plate to size desired.  Re-tape remainder and projected plate.

II. Film Preparation:

	Film is prepared for exposure onto Revere photo-sensitive zinc plate.  Kodalith 3  film  may
be  shot in the darkroom.  For intaglio processes, a film POSITIVE is made, always using a half-tone
screen.  A 133 dot screen is preferred.  Test  strips  should  be  shot  through  strategic  lights,
half-tones and darks at exposures from 45 to 75 seconds. Not only do you want the exposure that does
most for your particular image, but you want one that will carry a clear dot pattern in the  blacks.
This  is  one  of  the  most  important  considerations  in photo intaglio work.  After longest test
exposure, a 20 to 25 second "flash" is  recommended  --  with  negative  removed  from  carrier  and
enlarger  raised  all  the  way  up.   This is to insure a dot pattern in blacks (to hold ink in the
darkest areas).   Check you test strip results with a magnifying  glass.   When  you've  decided  on
correct  exposure  time  and  flash  time, shoot your plate-sized Kodalith positive(s).   For relief
printing on zinc, a Kodalith negative is used, and no half-tone screen  is  necessary.   For  grainy
silk-screen-like  prints, you should use this method.   I prefer a 1 part H2O, 1 part A and 1 part B
developer to the usual stronger mixture.  Thus, your image will come up slower  and  you  have  more
control.

	After  you  finish  with  your darkroom work, you will probably want to modify your Kodalith
through any one of many creative techniques.  You may wish to cut the film(s) up into a  collage  or
overlay (double image).  You may wish to scrape away large or small sections with a knife or etching
needle. You may wish to add blacks with brush or pen and ink (non-crawl acetate ink or India ink) --
or  with  litho  crayons  or  pencils.  You may wish to turn certain areas into cloud-like, vaporous
half-tones by applying a 50% clorox, 50% H2O solution with cotton.  Precise white lines are  created
in your intaglio print by scratching white lines out of inked or exposed film areas.

	If  you are drawing directly on film, without using a photographic negative, utilize .005 or
.007 acetate.  This may be collaged or overlaid also.  But remember to test overlays  carefully  for
longer  exposure.   Any drawing techniques just discussed may be used on acetate, plus any you think
just MIGHT work.   Film, either singly or in collage or overlay  must  be  the  same  size  as  your
intended photo plate in total dimension.  Remember, the image you see UP, as you lay the film on top
of your plate for exposure, will be MIRRORED in your final print.   Hence  all  writing,  lettering,
etc. should be BACKWARDS (emulsion side down) during exposure.

	Before exposure, pour Revere Developer into a metal or glass tray.
	Don't use rubber or composition tray.  Use well-ventilated area.

III. Plate Exposure:

	Photo plate exposure is done at the vacuum table with the  carbon  arc  lamp.  Safety  rules
against burns, fumes, and eye hazards should be carefully observed.   Keep arc UNPLUGGED when not in
use. Keep arc UNPLUGGED during placement and careful seating of carbons -- careful seating  prevents
sputters  and  disappearance  of  light during timed exposure.    The light table should be lowered,
opened, and checked for cleanliness. (Amonia solution or Windex wash inside and out.)  Plate  should
now  be  unwrapped.   (It  is  safe  under  flourescent light for about 15 minutes.) Place plate and
Kodalith film emulsion to emulsion on glass table, plate back to you.  You might check registration,
the avoidance of possible scratches in the glass, etc., by squatting under the table and looking up.
LOCK TABLE SECURELY. Start vacuum.  Don't lift table into exposing position  until  gauge  reads  25
lbs.  pressure.    Bring Carbon Arc Machine up to taped exposing position.  Set wings at 45 degrees.
Plug in Carbon Machine.  Open window. Close curtains.   Put  on  goggles.   Position  yourself  near
springed  timing  meter, back to vacuum table.  Remember to keep your eyes averted from carbon light
even with your goggles on.   Plan your quick retreat through the curtains once  timer  is  set.   No
exposure  is  effective  under  5 1/2 minutes.  Test exposures may be made anywhere from 5 1/2 to 15
minutes; average range is c.7 minutes to 12 minutes, depending on your  Kodalith  film  and  results
desired.   An exposure of 8 to 10 minutes would be absolutely average and safe for most cases. After
exposure, pull Carbon Machine plug.  Push Carbon Machine back to convenient location, being  careful
not  to  touch  carbons until they are absolutely cool.   Lower vacuum table to horizontal position.
Turn off vacuum.  Unlock and lift top.  Carefully remove your  plate,  without  touching  emulsioned
top.


IV. Plate Development and Wash-Out:

	Procedure for test strips and real plate is exactly the same.  With-  out  touching  top  of
plate,  carry  plate  to developer.  Submerge photo-plate with the same motion you use to enter film
into a developer.  Exposure time is 2 minutes (unless developer is very  old.)  Agitate  gently  but
continuously.  Do not breathe fumes.   The care with which you handle the plate when lifting it from
the developer and until it is completely "set" after several minutes of water wash-out  is  crucial.
This  is  the  crucial  time  of  the  whole  process  because  at  this time the resist is soft and
jelly-like.  Don't touch top!  In hot weather let plate drip in sink for one  full  minute.    Then,
with  a  VERY SOFT stream of COLD H2O, begin wash-out, keeping plate tilted at a severe angle to the
stream.  After about 2 minutes you can increase the amount of water in stream.  Wash-out should last
4 minutes.

	Set plate up leaning against a wall on top of a clean counter or table for 1/2 hour.  Funnel
your developer into re-cycling drum immediately.   Have another student hold funnel.    Clean  hands
thoroughly.  I suggest a 24-hour wait before acid biting.

V. Hand Work and Acid Baths:

	1.  Intaglio  plates  with  half-tone  screen  should  probably  be bitten 10 to 12 minutes,
depending on acid strength.  Open bite.  Then if there are some black areas that haven't received  a
dot  pattern,  the "tooth" to hold the ink in these spots must be supplied by aquatint (or drypoint,
if problem area is small).  Although rosin aquatint MAY be used, plastic spray is  preferred.   Bite
plate 4-8 minutes more, depending on bath strength (5 minutes average).

	2.   Plates  that are to be bitten for rolled relief printing should probably be bitten down
at least an hour.  Color viscosity biting can also be tackled at this point, if  desired.   However,
any  section  of  plate  defined  by  a  screen  should  probably not be bitten longer than an hour;
undercutting could destroy the pattern.

	3.  ANY kind of plate modification or etching or drypoint technique may be  utilized  either
before  first  bath  or  at  any  later stage.  Drypoint through the blue photo resist is beautiful.
Needled, etched lines may be added at any time.  The resist may be removed wholly or  in  part  with
acetone.  A  vaporous  effect,  unequalled in any other phase of etching, is achieved by dragging an
acetone-soaked rag over plate and eliminating resist  selectively.   Any  length  of  bath  follows,
depending  on  effect  desired.   Liquid  ground  can  form new resist patterns once photo-resist is
removed.  New aquatinted shapes can be created in counterpoint with the original photo half-tone  if
resist  is  partly  or  wholly  removed.  Taped hard-edges can be created over photo-image before or
after initial bath.   Whole new areas can be scraped or bitten:  these  practices  are  particularly
applicable  if  several  photo-plates  are  to be used in registration; the concept of "dropping out
colors" applies.