Copper Sulfate – Saline Etch for Aluminum – Refinement

The copper sulfate saline etch is a salt-based etching mordant designed for silvery metals such as aluminum, zinc and mild steel as a replacement to Fredhard Kiekeban’s ferric chloride-based ‘Edinborough Etch’ used for etching materials such as copper and brass. Based on the copper sulphate mordant originally designed by Nik Semenoff and published as the ‘Bordeaux Etch’ by Cedric Green, the copper sulfate saline etch was improved upon by Kiekeban by adding a mixture of sodium chloride (or table salt) to the mordant for a quicker, cleaner and crisper etch.

Our main task is to improve upon this etching process by focusing on aluminum plates and creating a ‘closed-loop’ system that recycles or re-purposes the displaced copper residue from the mordant. Thus creating a sustainable, consistent and non-toxic etching system that can be maintained safely in private and/or collaborative spaces that requires minimal upkeep and little to no waste. Along with this research, we’re also tasked in refining the overall image quality of etching on aluminum in order to expand the value ranges of an image and to have predictable times for etching these values. Due to the chemical compound of aluminum, the surface has a natural aquatint effect when etched, which results in unwanted plate-tone in the lighter areas of the plate. Our goal is to refine the etching process to exploit the potential of this natural aquatint and to retain the lighter, untouched areas of the plate, if so desired by the printer.

Our research began by reviewing notes and becoming familiar with the current copper sulfate saline etching process practiced at Zea Mays. Once we become familiar with this process, our next step will involve testing and manipulating various materials, mordant qualities and etch times. Our tests will include different qualities of aluminum, various etch times of varying strengths of mordant, monitoring the degeneration of the etch and the process of regenerating a mordant with recycled copper sulphate residue.

Researchers: Tessa Chambers and Nick Osetek

Test 1: Becoming Familiar w/ Zea Mays Process

Test 2: Line Work

Test 3: Aquatint Step-Test

Test 4: Aquatint Step Test (Part 2)

Test 5: 16-Plate Step Test

Test 6: Bath Strength Test

Test 7: Bath Strength Test (Part 2)

Test 8: Citric Acid Degeneration Test

Test 9: Citric Acid Degeneration Test (Part 2)

Test 10: Citric Acid Degeneration Test (Part 3)

Test 11: Citric Acid Degeneration Test (Part 4)

Test 12: Bath Regeneration Test

Test 13: Copper Sulfate + Depleted Bath Test

Test 14: 5-Gallon Bath

Test 15: Aluminum 1100 Etch Test

Test 16: Aluminum 5052 Mirror Step Test

Test 17: Nick’s Image Making

Test 18: Tessa’s Image Making

Test 19: 5-Gallon Bath Strength Test

Test 20: Large 3 & 5-minute Plates

Test 21: Depleted Bath Revival

Test 22: Mirror Step Test in Revived Bath

Test 23: Depleted Bath Revival #2

Test 24: Depleted Bath Revival #3

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