Test 5: Dialing in: Step Test for Image Positive

Step exposure tests at 5 – 9 LU for the film positive

researchers: Hannah Hurricane Sanchez

April 26, 2019
Room Temperature: 68° F
Humidity: 93%

Our objective for the day was to find the exposure time for the image positive that gave the richest darks, and subtle variations in light grays and dark grays. We designed a step test using a laminated PETG plate from 4/25/2019 that has the aquatint screen exposed at 5 LU and the image positive exposed at 4, 5, 6, 7,8, 9, and 10 LU.

Step test design for image positive.

using two cardboard pieces to block out light during step test exposure

Exposure unit on.

After exposure the plate was placed in the ImagOn developer for 9 minutes, the developer temperature was at 65.3°F. The developer was shaken prior to being placed in photo tray. After the 9 minutes the plate was rinsed well under cool running water, and sprayed with white vinegar and lightly rubbed for 30 seconds, and rinsed again with running water. After patting dry, the plate was placed for a final hardening exposure of 5 LU.

9 minute developer bath with cover.

rinse with running cool water, and sprayed with white vinegar for 30 seconds.

Printing the 5-9 LU exposed step test plate

To print the plate we used Akua Carbon black with 15% transparent base added to the ink. We soaked Hanemeuhle Copperplate paper for 20 minutes and blotted it removing excess water before printing. The Charles Brand etching press pressure was set at 9/1 with a pusher and a catcher blanket. Plate was wiped with a tarlatan and a final wipe with phone-book paper. Our printed results showed that we were achieving good tonal range at 5 through 6 LU. We noticed in the print, we have a heavy black line where we reset the vacuum during exposures, it’s recommended to not rest the vacuum in the future. To dial in even further an exposure time for the image positive, we designed a step test that went from 5 LU to 6.2 LU in .2 LU intervals.

inking plate

print showing results of step test 4 LU to 10 LU

Next step exposure tests at 5 – 6.2 LU (.2 LU intervals) for the film positive

A laminated PETG plate from 4/25/2019 was exposed to a 5 LU aquatint screen. With the image positive the plate was exposed to 5, 5.2, 5.4, 5.6, 5.8, 6.0, and 6.2 LU. Then placed into a ImagOn developer bath for 9 minutes. The developer was shaken before being placed in photo tray, and the developer temperature was at 64.8°F . After the 9 minutes, the plate was rinsed in cool running water, and then sprayed with white vinegar slightly rubbing for 30 seconds, and then re-rinsed with cool running water. The plate was dried and exposed to 5 LU for final hardening.

.2 LU interval step test exposure design

Printing the 5-6.2 LU exposed step test plate

To print the plate we used Akua Carbon black with 15% transparent base added to the ink. We soaked Hanemeuhle Copperplate paper for 20 minutes and blotted it removing excess water before printing. The Charles Brand etching press pressure was set at 9/1 with a pusher and a catcher blanket. Plate was wiped with a tarlatan and a final wipe with phone-book paper. Our printed results showed that we were achieving good tonal range at 5.6 through 5.8 LU. We experienced here a problem with our mechanics of blocking out the light on the exposure unit, and have a strip where there is a misaligned step and a heavier exposure. Pointing out the importance of having a good cover when performing a step test.

print showing result of the .2 LU interval exposure step test

Moving forward we want to investigate our film positive, and make sure that we are certain that our printer, and photoshop manipulation choices of the image are yielding the sharpest quality, and value ranges acheivable with the ImagOn HD film.

 

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