Practice: Copper plate etching 1: Ferric chloride

Now equipped with an etching press and gear for copper plate etching.  Very little time though. Leaving in a few days.

A quick update of today’s efforts;

Materials: Ferric Chloride, in tubs, 3 kg and a large vertical tank, and a Baumeter:

I followed the instructions to mix 1 part FC with 4 parts water, and ended up with something that measured only 20 Baume, instead of the desired 40-45. Then I should have sat down and though things through in terms of worst case scenario, instead of what I did which was to adopt the modify and let’s see approach. With hindsight, I should have:

a. Measured the Baume by taking a sample into a narrow plastic container that was capable of floating the baumeter, and so had an idea that it wasn’t working as per the instructions.

b. Having discovered it wasn’t working, should have somehow extracted some of the liquid from the tank – difficult given the shape- and mixed more Ferric chloride into the solution, instead of diluting more, albeit in a very reduced amount of water.

c. Considered that Inductive reasoning wouldn’t necessarily work, i.e. adding another 1 kg brought to from 20 Baume to 30 Baume, therefore adding another 1 Kg will bring it up to 40 plus, especially if I use less water this time.

d. Poured the dilute stuff into a container and started again.


Anyway what’s done is done, and all my FC is diluted, and I’ll now just have to experiment to see how it works on copper. When I get back to HK, I’m definitely trying to source ready mixed.

The trouble was there were so many dire warnings about mixing FC and water that I was completely obsessed with the hazards, and also was completely ignorant about the stuff and didn’t know what to expect.  I now see that my stuff was already a bit damp, i.e. hydrated, and therefore less explosive. But that also means that 1 kg of damp stuff was considerably less than a KG of powder/ crystals, and presumably the “recipe” I had was for that. Wish I’d done some Chem.

On the upside, I am now more acquainted with FC, and will know better how to deal with it next time. $$$. Hassle of sourcing it. AArgh.

Experiment with copper plate. This is the back of a small one that was my experimental plate in Capileira.

Just to try:

1. Used some different materials to stop out the etching: spray stop out brushed on (Lascaux)

2. Acrylic marker pens.

3. Litho pencils

4. Wax crayon.

These would all be whit-ish s they are stopping out prior to the aquatint layer.

Then I sprayed the plate with an aquatint layer, (acrylic ink with airbrush- also sprayed a dense area) and dipped it for 1 minute in the FC mix. (using vinegar/ salt solution to de-oxidize in between.)

5. Used a litho pencil to mark “1 minute more” and dipped for 2 minutes (3 mins total)

6. Used a couple of different acrylic markers to write  “5 minutes” and dipped for 5 minutes (total 8 minutes)

7. Acrylic marker ” 30 minutes” (total 38 minutes)


What this taught e was the difference in edges- the acrylic pens are very effective. The airbrush spray is softer. The shades of grey are not very distinct and tend to merge with the aquatint speckled effect in the shorter exposures. Litho pencil – less so- and wax crayon gives a drawn line/ texture. I realise I need to work in shorter intervals but recognise the 5 minute mark as a clear grey.



Author: chrisocaprintingblog

Studying visual arts part-time with the Open College of the Arts

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