Date: February, 2014
Room temp: 71 humdity:dry
Researcher’s Name: Liz Bannish
Objective: Is an lpi higher than 80 lpi better for image retention? Also, a new set of curves values was tested at the same time to see how new values react with each lpi.
Plate Material: Copper 0.032
Plate size: 4.5X6″
Plate Preparation: polished with 00 grade steel wool, beveled and degreased with dish soap and soy sauce.
Image was prepared in Photoshop:
Opened and changed to TIFF file
Image>new adjustment layer> Invert
Img>new adj layer>Channel Mixer. Selected “monochrome” option
Img>new adj layer> Curves. 3 points on the curve:
Input 20/Output 0
Input 129/Output 127
Input 219/ Output 171
Input 253/Output 200
Printer settings:
HQ1200
Gray Gamma 2.2
Print option–shape: round
Plate A: All of the above settings except the lpi (lines per inch) was kept constant at 80 lpi
Plate B: All of the above settings except the lpi was changed to 110 lpi
Time in bath: 35 min. Etching bath notes: both plates etched fine,
Ground removal: SoySolvII
Paper: Hanhemule copperplate, soaked 10 minutes
Press: Takach, 2 thin blankets
Plate A, film after ironing
Plate B, film after ironing
Conclusions:
Plate A, proof
Plate B, proof
The 80 lpi image had better detail and value retention than plate B with 110 lpi; in the case of plate B the dots placed by the printer were too close together and ferric couldn’t bite through; thus leading to loss of detail. Continuing printing at 80 lpi or perhaps a little higher; but no more than 90 lpi is recommended.