Copper Plate Photogravure - Single Acid Etch - Significantly Shorter and Simplified Process
The process outlined below was devised during a workshop demonstration. We had an extra processed gelatin step tablet on copper and etched it in a single bath of ferric chloride. Instead of controlling the humidity and waiting hours for the gelatin to dry the plate was placed on a hot plate to dry. After twenty-five minutes the plate was cooled to room temperature and placed in one ferric chloride etching bath. I was surprised it worked and have been using this method with fairly consistant results ever since. If a film positive and tissue are prepared in advance it can take less than two hours to process a photogravure plate. The process outlined below was created using Dragon Gravure Tissue and an Epson Printer. It is a simple outline. There is a considerable amount of information between the steps.
Create a film profile limited to a maximum density of 1.4.
Print a digital 21 step tablet on your film of choice.
Sensitize Dragon Tissue in a 4% potassium dichromate solution chilled to 45 degrees for 75 seconds.
Use equal tone and aquatint exposures.
Degrease the copper.
Place the degreased copper plate in distilled water chilled to 45 degrees.
Slide the exposed tissue face side up into the tray with the copper.
Flip the tissue over and position it over the copper. Remove the copper and tissue from the bath at a gentle angle. I use a thick glass sheet positioned on an overturned tray in my my sink as a surface for laminating the gelatin tissue and the copper. The surface you squeegee on should be close to the temperature of your mating bath.
Blot the backing paper and wait 75 seconds.
Immerse the plate into 115 degree development water. Wait two minutes before peeling the tissue.
After 4-8 minutes of minutes of agitation and hosing the clearing is complete.
Place the plate in a 50% tray of isopropyl alcohol bath for 2 minutes. Remove the plate from the alcohol and flood with 75% isopropyl. Agitate the plate in hand. Flood the plate twice within 45 seconds.
Dry the plate as evenly as you can. Rock the plate and watch the alcohol closely. Modify your technique to make the alcohol evaporate as evenly as possible.
Allow the plate to rest with air circulation for twenty minutes.
Mask the plate.
After twenty-five minutes of total drying place the plate on a hot plate heated to 120 F for twenty-five minutes.
After twenty-five minutes move the plate to a room temperature surface.
As soon as the plate has cooled to room temperature etch in 40.3 ferric chloride.
Proof.
Create a profile. Make plates - Make prints.
Review the photogravure reference page for trouble shooting and more information.
Tips:
Look closely at everything.
If you have problems run through the entire process with very bright lights on.
Use a head magnifier.
If something is not working properly repeating what you did will not make it work.
Experiment - read - study. Do not believe everything you read.
Don’t sneak up on things. Test and test again.