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University of Tennessee Department of Classics

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Welcome! » Transmission Electron Microscopy » Darkroom Excercise


Darkroom Excercise

To get various shades of gray and contrast, it is necessary to use filters. The lower number filters give less contrast (more grays) and the higher number filters give more black and white. From experience with this paper and with biological tissue, the average negative of tissue (liver) usually requires a filter in the F4 range.Carbon hole and negative stain preps may require  another filter. This will be worked out and the information will be passed along to you.

PROCEDURE FOR USE OF THE DARKROOM AND MAKING

GLOSSY PRINTS FROM NEGATIVES

  1. Sign up for the darkroom to reserve a block of time. If a conflict develops, be sure to cancel so someone else can use the facility.
  2. Prepare the solutions in the appropriate pans. Use the same pans consistently for Developer,  Stop-bath, Fixer, and rinse.
    1. Developer: Kodak Dektol.  Dilute 1 part Dektol stock solution with 2 parts water.
    2. Stop-bath: Water-Acetic Acid. Add 48 ml. Acetic Acid to 1 liter water or one can use Kodak Indicator Stop-bath and follow directions on the bottle.
    3. Fixer: Kodak Fixer (use full strength). If dark discard the fixer.
    4. Rinse: Running water
  3. Turn on safe lights and "in-use" room light.
  4. Check the enlarger for proper lens and condenser. For the Hitachi (3 1/4 X 4) negatives,  use the 135 mm lens and position 1 (top) condenser setting.
  5. Place filter, number side up, on top of the condenser.
  6. Place film in holder, emulsion side down (flat and dull).
  7. Place holder in enlarger.
  8. Turn out room lights.
  9. Run enlarger up or down to obtain desired size photo.
  10. Center image on easel.
  11. nsert practice paper and focus image, with F stop open for maximum light, using scopenet.
  12. Turn off enlarger light with switch on timer.
  13. Set F stop on enlarger to desired shutter opening (f11 or f16) and set timer to desired number of seconds. (Combination determined previously by use of test strips).
  14. Insert paper in easel, emulsion side up. (shiny side)
  15. Expose paper by pressing the exposure button on the timer.
  16. Place paper in developer. Do not let paper curl up and become exposed to air.
  17. Watch development. Image should come up evenly. Development time varies, but development should be complete within 1 1/2 to 2 minutes
  18. Pick up print with tongs and drop it into stop bath. Replace tongs in developer pan.
  19. Swish print through stop-bath with stop-bath tongs. Pick up print and drop it into the  fixer pan. Replace stop-bath tongs.
  20. Poke print into fixer with fixer tongs. Print should stay in fixer for a minimum of 2 minutes. Longer fixation is O.K., but do not leave longer than 10 minutes.
  21. Remove print with fixer tongs and drop into a pan of running water. With RC paper,   do not wash much longer than 4 minutes, or you will have problems with water   entering between the resin and the paper, encouraging curling at the edges.
  22. Let prints drain briefly and hang on line with clips to air dry. Prints can also be put  into the negative dryer, alternating spaces to avoid prints sticking together.
  23. When you are done printing (after asking the next user if they need the chemicals), do the following:
    1. Wash all pans thoroughly and stack to dry.
    2. Wash sink, table tops and floor.
    3. Turn off safelights.
    4. Turn off room lights and the "In Use" light.
    5. Put away all darkroom materials.