00100				PHOTO ETCHING INSTRUCTIONS
00200				Edith Smith, Instructor
00300	
00400	I. Cut photo-plate to size desired.  Re-tape remainder and projected plate.
00500	
00600	II. Film Preparation:
00700	
00800		Film is prepared for exposure onto Revere photo-sensitive zinc plate.  Kodalith
00900	3  film  may be shot in the darkroom.  For intaglio processes, a film POSITIVE is made,
01000	always using a half-tone screen.  A 133 dot screen is preferred. Test strips should  be
01100	shot through strategic lights, half-tones and darks at exposures from 45 to 75 seconds.
01200	Not only do you want the exposure that does most for your  particular  image,  but  you
01300	want  one  that  will carry a clear dot pattern in the blacks.  This is one of the most
01400	important considerations in photo intaglio work.  After longest test exposure, a 20  to
01500	25  second  "flash"  is  recommended -- with negative removed from carrier and enlarger
01600	raised all the way up.  This is to insure a dot pattern in blacks (to hold ink  in  the
01700	darkest  areas).   Check  you  test strip results with a magnifying glass.  When you've
01800	decided on correct exposure time  and  flash  time,  shoot  your  plate-sized  Kodalith
01900	positive(s).   For  relief  printing  on  zinc,  a  Kodalith  negative  is used, and no
02000	half-tone screen is necessary.  For grainy silk-screen-like prints, you should use this
02100	method.   I  prefer a 1 part H2O, 1 part A and 1 part B developer to the usual stronger
02200	mixture.  Thus, your image will come up slower and you have more control.
02300	
02400		After you finish with your darkroom work, you will probably want to modify your
02500	Kodalith  through any one of many creative techniques.  You may wish to cut the film(s)
02600	up into a collage or overlay (double image).  You may wish  to  scrape  away  large  or
02700	small sections with a knife or etching needle. You may wish to add blacks with brush or
02800	pen and ink (non-crawl acetate ink or India ink) -- or with litho crayons  or  pencils.
02900	You  may  wish to turn certain areas into cloud-like, vaporous half-tones by applying a
03000	50% clorox, 50% H2O solution with cotton.  Precise white  lines  are  created  in  your
03100	intaglio print by scratching white lines out of inked or exposed film areas.
03200	
03300		If  you  are  drawing  directly on film, without using a photographic negative,
03400	utilize .005 or .007 acetate.  This may be collaged or overlaid also.  But remember  to
03500	test overlays carefully for longer exposure.  Any drawing techniques just discussed may
03600	be used on acetate, plus any you think just MIGHT work.   Film,  either  singly  or  in
03700	collage  or  overlay  must  be  the  same  size  as  your intended photo plate in total
03800	dimension.  Remember, the image you see UP, as you lay the film on top  of  your  plate
03900	for exposure, will be MIRRORED in your final print.  Hence all writing, lettering, etc.
04000	should be BACKWARDS (emulsion side down) during exposure.
04100	
04200		Before exposure, pour Revere Developer into a metal or glass tray.
04300		Don't use rubber or composition tray.  Use well-ventilated area.
04400	
04500	III. Plate Exposure:
04600	
04700		Photo  plate  exposure  is  done  at the vacuum table with the carbon arc lamp.
04800	Safety rules against burns, fumes, and eye hazards should be carefully observed.   Keep
04900	arc  UNPLUGGED when not in use. Keep arc UNPLUGGED during placement and careful seating
05000	of carbons -- careful seating prevents sputters and disappearance of light during timed
05100	exposure.    The  light  table  should be lowered, opened, and checked for cleanliness.
05200	(Amonia solution or Windex wash inside and out.) Plate should now be unwrapped.  (It is
05300	safe  under  flourescent  light  for  about  15 minutes.) Place plate and Kodalith film
05400	emulsion to emulsion on glass table, plate back to you.  You might check  registration,
05500	the  avoidance  of  possible scratches in the glass, etc., by squatting under the table
05600	and looking up.  LOCK TABLE SECURELY. Start vacuum.  Don't  lift  table  into  exposing
05700	position  until  gauge  reads  25 lbs. pressure.   Bring Carbon Arc Machine up to taped
05800	exposing position.  Set wings at 45 degrees.  Plug  in  Carbon  Machine.  Open  window.
05900	Close curtains.  Put on goggles.  Position yourself near springed timing meter, back to
06000	vacuum table.  Remember to keep your eyes averted from  carbon  light  even  with  your
06100	goggles  on.   Plan  your  quick  retreat  through  the curtains once timer is set.  No
06200	exposure is effective under 5 1/2 minutes.  Test exposures may be made anywhere from  5
06300	1/2  to  15  minutes;  average  range  is  c.7 minutes to 12 minutes, depending on your
06400	Kodalith film and results desired.  An exposure of 8 to 10 minutes would be  absolutely
06500	average and safe for most cases. After exposure, pull Carbon Machine plug.  Push Carbon
06600	Machine back to convenient location, being careful not to touch carbons until they  are
06700	absolutely  cool.   Lower vacuum table to horizontal position. Turn off vacuum.  Unlock
06800	and lift top.  Carefully remove your plate, without touching emulsioned top.
06900	
07000	
07100	IV. Plate Development and Wash-Out:
07200	
07300		Procedure  for  test  strips  and  real  plate  is exactly the same.  With- out
07400	touching top of plate, carry plate to developer.  Submerge photo-plate  with  the  same
07500	motion  you  use  to  enter  film into a developer.  Exposure time is 2 minutes (unless
07600	developer is very old.) Agitate gently but continuously.  Do not  breathe  fumes.   The
07700	care with which you handle the plate when lifting it from the developer and until it is
07800	completely "set" after several minutes of  water  wash-out  is  crucial.  This  is  the
07900	crucial  time  of  the  whole  process  because  at  this  time  the resist is soft and
08000	jelly-like.  Don't touch top!  In hot weather let plate  drip  in  sink  for  one  full
08100	minute.   Then,  with  a  VERY  SOFT  stream of COLD H2O, begin wash-out, keeping plate
08200	tilted at a severe angle to the stream.  After about 2 minutes  you  can  increase  the
08300	amount of water in stream.  Wash-out should last 4 minutes.
08400	
08500		Set  plate up leaning against a wall on top of a clean counter or table for 1/2
08600	hour.  Funnel your developer into re-cycling drum immediately.   Have  another  student
08700	hold funnel.   Clean hands thoroughly.  I suggest a 24-hour wait before acid biting.
08800	
08900	V. Hand Work and Acid Baths:
08950	
09000		1. Intaglio plates with half-tone screen should probably be  bitten  10  to  12
09100	minutes,  depending  on  acid strength.  Open bite.  Then if there are some black areas
09200	that haven't received a dot pattern, the "tooth" to hold the ink in these spots must be
09300	supplied  by aquatint (or drypoint, if problem area is small).  Although rosin aquatint
09400	MAY be used, plastic spray is preferred.  Bite plate 4-8  minutes  more,  depending  on
09500	bath strength (5 minutes average).
09600	
09700		2.  Plates  that are to be bitten for rolled relief printing should probably be
09800	bitten down at least an hour.  Color viscosity biting  can  also  be  tackled  at  this
09900	point,  if  desired.  However, any section of plate defined by a screen should probably
10000	not be bitten longer than an hour; undercutting could destroy the pattern.
10100	
10200		3.  ANY kind of plate modification or etching  or  drypoint  technique  may  be
10300	utilized  either  before  first  bath or at any later stage.  Drypoint through the blue
10400	photo resist is beautiful.  Needled, etched lines may be added at any time.  The resist
10500	may  be  removed  wholly  or in part with acetone. A vaporous effect, unequalled in any
10600	other phase of etching, is achieved by dragging an acetone-soaked rag  over  plate  and
10700	eliminating  resist  selectively.  Any  length  of  bath  follows,  depending on effect
10800	desired.  Liquid ground can form new resist patterns once photo-resist is removed.  New
10900	aquatinted  shapes  can be created in counterpoint with the original photo half-tone if
11000	resist is partly or wholly removed.  Taped hard-edges can be created  over  photo-image
11100	before  or  after  initial  bath.   Whole  new  areas  can  be scraped or bitten: these
11200	practices are particularly applicable  if  several  photo-plates  are  to  be  used  in
11300	registration; the concept of "dropping out colors" applies.