press n peel test 24
Date: October 8, 2013
Room Temperature: 66 degrees Farenheit, dry
Researcher’s Name: Cathe Janke and Kristin Fitzpatrick
The purpose of this test was to see if changing the image format and filter settings would change the image fidelity and give us a greater tonal range.
Plate Material: .032 Copper Plate Size: 4.5″ x 6”
In Photoshop with the image file open, we made the following adjustments
1. Image>size> 250 dpi
2. Layer> New Adjust Layer> Invert
3. Layer> New Adjust Layer> Color Balance Highlights- Cyan= -31 Magenta= 0 Yellow= -26.
4. Layer> New Adjust Layer> Curves
Curves: Black=45 White=225. Two middle points: Output 62/Input 64 (the gray-black) and Output 171/Input 175 (the gray-white). Or A: O: 45 I: 0 B: 0:62 I: 64 C: 0:171 I: 175 D: 0: 225 I:255
5. Select background layer then Layer> Duplicate layer> background copy selectedClick opacity (by layers) select 75% *turn background (original) OFF, before printing (press eye
6. Flatten Image (under image)
7. Image> grayscale
8. Bitmap (under image)
-select “Diffusion Dither”
For test 4.1 changed resolution output to : 2.500 pixels per inch
For test 4.2 changed resolution output to: 1,250 pixels per inch.
View of the image in Photoshop 2500 bit
When printing”printer profile” option not available (this is because of bitmap)
Print Parameters Used
Let Photoshop determine colors
Gray Gamma 2.2
Presets= Plain Paper
Resolution HQ 1200
The image was printed on the PCB film with a Brother HL2280DW laser printer.
Plate Preparation : We used two for this trial. The plates were beveled, polished with 00 grade steel wool, and degreased with soy sauce and bon ami.
The copper plate was placed on a phone book and the film was placed on its surface print-side-down. The film was carefully heated to the plate with a tacking iron for 8 minutes at 300 degrees F.
Testers found that backing the plate with contact paper was most pragmatic AFTER the plate had been ironed and cooled and with the film still adhered to the plate
Etching Notes: The plate was etched in a 39 degrees Baume Ferric Chloride bath in a vertical tank.
Time in Bath 30 minutes
Removal of Grounds : Plates were saturated with SoySolvII cleaner and left to soak for 5 minutes. Ground was then wiped off easily with a rag.
After Bath Evaluation: open bite on 1250 and open bite on 2500 almost all black areas open bit
Inking Methods : Plate was inked with Graphic Chemical Etching Ink in Bone Black, applied with a piece of mat board. It was gently wiped in an outwards motion with a piece of tarlatan. Then paper wiped.
Paper Type: Hahnemuhle, white Paper Soaking Time: 30 Minutes Press Blanket Setup: Takach pressure at 5.5, 2 blankets, sheet of newsprint
Bit map/dither was not effective and the next test will try a photocopy of a tonal drawing to see if issues exist in Photoshop or with PCB film.