ART375 - Photographic Processes of Printmaking

Positive Plate Lithography Steps

  • Pre-Press
  • Pin Registration
  • Burn Out Mask –Double Burn
  • Exposing the Plate

 

Pre-Press PREP

  1. Prepare Paper, Newsprint, Mylar and Plate
  2. Tear down your paper to fit your image (Note: The paper should be 1 inch longer than the final paper size and should not be larger than the plate in any direction)
  3. The newsprint should be larger than your printing paper.
  4. Prepare as many sheets of newsprint as sheets of paper you will be printing plus at least 4 extras. The newsprint should be larger than your printing paper.
  5. Mylar should be slightly smaller than the plate or same size.
    When all materials are with you
  6. Using the Punch table place your Paper (one at a time) in the punch area, make sure the paper is centered on the punch system you have selected. The selection is based on the width of your paper. Check that the same amount of paper extends on both sides beyond the selected holes.
    Always use the widest spread of holes that fits in your paper.
    Punch your paper printing face up.
    Punch your mylar using the same method of determine the center of the mylar.
    Punch your LIGHT SENSITIVE plate face down. (shinny aluminum side up) Use same method for determining holes positions as you did for paper.

 

Pin Registration

  • Placing the Pins through your paper
  • Placing the Mylar over the paper on the pins.
  • Take your imaged transparency and position it emulsion side up exactly where you want it to be on the paper when printed.
  • When in the position you want tape the corners with small pieces of clear tape.

If you have a multiple set of transparencies then the next piece of mylar is placed over the first and line up your printer marks .. when all is in place tape the new transparency.

 

Burn Out Mask - For a Double Burn

An additional mylar is placed over the images and a piece of rubylith is cut to fit the image area and taped into place on the extra mylar. This Mylar & Rubylith will be used to burn away any printer marks or stray marks.

 

Exposure Times


In theory, you want the shortest exposure possible, while still exposing the plate long enough that the non-image areas of the plate develop away cleanly or only leave a very faint haze.
When testing translucent materials, it is easy to determine the correct exposure by making several test plates in small increments, and finding when the fog or haze left on the plate by the translucent film fully disappears during developing.

  • Approximate Exposure Times for the Amergraph 150 .003 Drafting Film (Single Sided):  16lu
  • Artex Textured Film: 22lu Pictorico OHP Inkjet Transparencies: 28 lu
  • Oiled Laser Prints/Photocopies/Inkjet Prints: 68 light units

All times are approximate! You may need to test your images individually. Remember to expose ‘emulsion to emulsion’.

 

Exposing

  • Turn on the exposure unit and set the desired exposure time
  • Using the shallow well side .. open the glass door.
  • Put a pin bar down and place your plate emulsion side up over the pins.
  • Using the pins that are sticking through the pate position your Mylar with the image transparency film face down.
  • Carefully close the Glass door and Make Sure the Glass Is Closed and handles are locked.
  • Turn on the proper vacuum and wait till the pressure builds
  • Flip the top over to allow for exposure.
  • Hit the T button and expose for the set time.
  • When light goes out flip the top back over and turn off vacuum.
  • After pressure has been released open the glass door and remove all of your materials.