A word of warning about copper sulfate etchant

Last year I posted the recipe for an aluminium and zinc etchant made from copper sulfate. I forgot to add something very important.

Before you etch anything in this, stick an unprotected piece of aluminium into it, about 1x3 inches large. Leave it there for 5-10 minutes. This will take the edge off it so it isn't so strong. If you don't do this, the first plate you etch may become a complete mess. It will bite your needlepoint lines into lines 2mm wide, and it will even bite holes through areas protected by the ground.

Alternatively, when etching your first plate, just make sure to check it every 3-5 minutes to make sure it isn't being ravaged.

It isn't nitric acid, but it is extremely strong.

I forgot to do this just now and have suffered the printmaking equivalent of my computer crashing after drawing something on illustrator for 4 hours and not saving it.

A pint of that red stuff

One of the problems with etching aluminium in copper sulfate is the buildup of Red Stuff (technical name unknown) that occurs in the etched lines. Feathering doesn't always relieve this. I've gone so far as to scrub the plate with one of those rough sponges you use when washing cookware in an attempt to remove it. This is not recommended because it may scratch the plate and doesn't totally work anyway. Definitely don't do it with the ground still on, because it will scratch your ground. The Red Stuff must be removed because it stops the ink from going into the lines and you end up with the Most Horrible Broken Lines Ever.

Here's a picture of the Red Stuff on the plate and a picture of the resulting proof, to show you how troublesome the Red Stuff can be.





Sometimes the only way to remove the Red Stuff is to go over the lines lightly with your etching needle to dig them out. This is a pain in the ass to do so if you've found alternative methods, let me know.

This is what the plate looks like after the Red stuff has been removed.



And the resulting print, lines intact. (Ignore the colour. I can't find a proof which I haven't already painted)



And to promote myself, here is what the actual artwork looks like as a whole. It is part of my Bahay Kubo series, which you may view on Etsy. Bataw is Hyacinth bean in English, and Lablab purpureus in Science :)



I won't be using aluminium for a while because I've just bought a nice big pile of copper plates (from Neil Wallace Printmaking Supplies, Melbourne) and am (temporarily?) switching to etching copper with ferric chloride. The next post will show you my semi-horrible first attempt at etching a copper plate.

Safe etching part 1: aluminum

Finishing my Design degree at COFA last year brought with it the reality that I was no longer entitled to use their superior printmaking facilities and staff. Since then I have enrolled in a weekly class at the only open studio I could find in Sydney, which is in Manly Vale, 80 minutes public transport away from where I live.

This studio is a 'safe' studio. This means they universally encourage people to use photopolymer (solar) plates which don't use anything more toxic in its etching process than UV rays, water, and photocopying toner; that there is a distinct lack of turps and meth; and that if you must etch metal, you won't find any nitric acid for it.

There are substitutes for this. To clean the ink, we use vegetable oil. Not as fast and efficient, but definitely better for inhaling (oh, and it's edible). For etching zinc we use a mixture of copper sulfate and water.

So far I've worked mostly with aluminum plates, primarily because they are cheap. A zinc plate of the same size generally costs 10 times as much. There is a relatively safe etchant you can mix up at home for aluminum. I wouldn't recommend sticking your fingers in it or drinking it, but at the very least it is unlikely you'll pick up any thrid degree burns from it.

The recipe for aluminum plate etchant:
2 litres cold water
1 cup copper sulfate
1/2 cup salt
1 tbsp sodium bisulfate

You can buy copper sulfate from gardening stores (it's blue) and sodium bisulfate can be found in some powdered toilet cleaners (harpic in Australia).

Shake up the lot in a large container and pour it into a plastic tray. Photographic chemical trays work well. And there you have your etchant!

This post is horribly incomplete and has therefore been updated here.

Here is an excellent, in depth article about copper sulfate etching, by Nik Semenoff.