After my initial experiments with the etching process, I started today to apply what I have learned to my Exmoor tree images.
(See previous etching blog for my first steps in this process).
I opened one of my images into Photoshop, increased the contrast, applied the “Posterise” function and then deleted the background elements I didn’t want to print. The image was then flipped horizontally, and resized to fit the plate. This was then printed on the laser printer. The polished plate was cleaned thoroughly with white spirit, then covered in nail polish remover before applying the printed image, resting gently on the plate while the acetone softens the toner. Then a few layers of newspaper are placed on top of the image before adding a weight and leaving for a couple of hours. Once the weight hs been removed the now dry plate has the paper printed image stuck to it. The paper needs to be soaked off in warm soapy water and gently rubbed away leaving the toner image on the plate. To add some texture to the sky I brushed on some vegetable oil (Thanks Tony Martin – see reference – for this tip).
With the addition of Sodium Biosulfite to the Salt/Copper Sulfite solution to aid the etching process (See Reference), the plate was placed in the solution for 10 minutes, gently brushing away the copper deposits with a feather.
The etched plate was cleaned and used to produce relief prints. However the backround printed as intensely as the tree. (Print on the left, plate on the right).
After a number of trials it became clear this could be controlled with the stiffness of the paper.
It turns out that 200g/sm Inkjet/laser photopaper (Matte) works superbly. Very rewarding morining’s work.
“When I developed my copper sulfate etch in 1992, I realized that mixing sodium bisulfate into the bath to keep aluminium hydroxide from forming, was actually making a weak hydrochloric acid that produced hydrogen in reaction with the metal, which gently lifted the pure copper particles out of the etched lines.”