Test 4: Test Printing and Finding an Exposure Time

Researchers: Dan Dawson

April 25, 2019
Room Temperature: 68°F
Humidity: 51%

After testing our ImagOn developer, laminating plates, creating an image positive and exposing the plate to both an aquatint screen and the image positive it was time to print our image. First though we would need to find an exposure time, to do this we set up a step test. Using the 26-1K NuArc Mercury Exposure System, we had already determined that an exposure of 5 L.U. worked well for our aquatint screen, and the week earlier we had prepared a plate to print by exposing the aquatint screen to 5 L.U. and also the image positive to 5 L.U. as a starting point.

Test Printing the 5 L.U. exposed plate

Using:
Carbon Black Akua ink
Hanemeuhle Copperplate paper, soaked and blotted
wiping with a tarlatan and newsprint
Charles Brand etching press set to 9/1 with two sizing catcher blankets

Results:
very strong blacks, not enough lights or mid-tones.

Test print of plate. Both aquatint screen and image positive exposed at 5 L.U.

Because the print holds no tonal value it indicates that the image positive is being overexposed and/or underexposed. From here we decided to design a step test to dial in the exposure time.

Finding an Exposure Time

Under darkroom conditions we spray laminated a new plate on a piece of PETG, and exposed that to 5 L.U. aquatint screen. When exposing the image positive we choose a step test method, exposing in 5 L.U. intervals from 5 to 30 L.U. The plate was then placed in the developer bath (65.1°F) for 9 minutes, then it was rinsed in cool water, sprayed with vinegar, and rubbed for 30 seconds, rinsed and dried.

Plate sitting in the 9 minute developer bath

 

Printing the 5 L.U. to 30 L.U. step test plate

Using:
Carbon Black Akua ink
Hanemeuhle Copperplate paper, soaked and blotted
wiping with a tarlatan and newsprint
Charles Brand etching press set to 9/1 with two sizing catcher blankets

Results:
with increasing our exposure time in 5 L.U. intervals we noticed significantly more whites but no more tonal range. Given the results we saw the most promising results of tonal range between 5 L.U. and 10L.U.

5 L.U. – 30 L.U. Step Test Result

Here, we decided that we should conduct another step test with much smaller L.U. intervals. Our next step test would expose the image positive at 1 L.U. intervals between 4 L.U. and 10 L.U.

The plate on the right is the 5 L.U. interval step test form 5 to 30 L.U., the plate on the left is the all-over 5 L.U. exposed plate, and  below the plates is the image positive printed on Pictorico.

 

<previous experiment                                                                                                                 next experiment>