Etching of copper roofing panels for Artwork
I am a printmaker/artist living in Northern Alberta, Canada and have some questions about etching copper that you may be able to help me with.
I use Riston photopolymer film laminated on to roofing copper plates which are exposed to my art work or photographic halftone and then subsequently etched in ferric chloride. After the plate is etched it is cleaned and printed as an etching.
I had heard of the Peroxy-sulfuric method of etching. This system sounds great but can you give me a formula by which I could mix the constituent parts of this solution. i.e., 35% Hydrogen Peroxide [linked by editor to product info at Amazon], sulfuric acid, copper sulfate and organic stabilizers. What are organic stabilizers? Can you give me an indication if this is something that I could purchase easily. For instance I know that I can buy the copper sulfate at the local Pivy Mart Store as this is what is used to purify dug-outs. I am really interested in availability and possible substitute products.
Also what is Ammoniacal etching of copper? Does this mean I can purchase some industrial strength ammonia and use it as a mordant or copper etching solution?
What alternative exist for me if I want to etch into a copper plate?
Yours sincerely,Keith Howard
I no longer have access to the reference, but look for an older book (say,1970) on the manufacture of printed circuit boards, they might have a simple way to prepare and use sulfuric-peroxide and ammoniacal etchants. Proprietary chemicals, such as the organic stabilizers, are sold by chemical companies in the directories of these pages.
I found this in the 1941 Chemical Formulary:
Etching of Copper and Brass
Usually dilute nitric acid solutions are used but for bulk etching, the following solution is recommended:
Water - 50 oz.
Sulfuric acid - 30 oz.
Potassium Chloride - 5 oz.
Concentrated Nitric Acid - 15 oz.
I think you would be better off buying a proprietary formula from a supplier if you use a drum or so every month. They would be able to work up some costs for you if you called them. Look in our directories for phone numbers.
Purify "dug outs"? You mean like a dugout where baseball players sit?
Dug out canoes?
I would love to know.
Look in our (voluminous) resources for book lists where you can buy the latest and greatest.
If you were contemplating medium to high production, you could probably buy a few sections of a previously owned printed circuit board etching machine, and adapt it for your plates. It is only a pump distributing etchant to spray nozzles in a covered area over a sump, with a conveyor of little rubber wheels on a chain. You may already be doing this, but you could control the etching depth by making the speed of the conveyor fast enough so you need a few passes to finish the job. This would be a lot easier than dipping plates into tanks, if that is what you do. Of course, automating something takes all the fun out of it:-}
I don't know how this would change how you control pollution, but you can regenerate the ammonia and sulfuric-peroxide etches; I think you get copper sulfate crystals back.
Falls Township, Pennsylvania
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