Sunday, August 6, 2017

A mammoth etching episode

©2017 Fiona Dempster - Deep etch
Fiona and I had set aside this morning to etch the 22 plates I have drawn up and blocked out for the five post snake and water motif sculpture I have been commissioned to do. Good news is that we got to do the job.

We dissolved  1kg of copper sulphate and 1kg of salt in 10 litres of hot water - lovely colours. Even though this etching process is sometimes referred to as non-toxic it needs to be done outdoors with all the necessary safety gear as it does give off fumes and it can burn the skin and eyes.

©2017 Barry Smith - Copper sulphate and salt. 
©2017 Barry Smith - Add hot water and the chemical reaction starts
We began by leaving the plates in the etching bath for 5 minutes; but the mixture loses its potency as it goes along; so the last batch ended up being in the bath for just on 10 minutes. In the earlier stages there is also a lot of heat - this diminishes as the etch goes on.

©2017 Barry Smith - Very active and hot etching reaction
To improve the etch Fiona was removing the floating copper residue off the surface as we progressed.

©2017 Barry Smith - Removing floating residue 
©2017 Barry Smith - Floating copper residue in the form of the snake being etched - quite the reaction going on
The plates look pretty messy when taken out of the bath; and need to be cleaned with a strong pressure of water as soon as they are out. If you don't wash the plates off the residue just fouls up the surface of the plates and makes for harder cleaning later.

©2017 Barry Smith - Messy looking etched plates 
©2017 Fiona Dempster - More plates in need of a good wash
©2017 Barry Smith - Barry cleaning plates with water jet
We ended up with a great line up of etched plates - washed and dried and put out for the final drying before cleaning the paint and shellac block-out off.

©2017 Fiona Dempster - A very satisfying line up of etched and washed and dried plates.
©2017 Fiona Dempster - Close up of some of the snake plates.
©2017 Fiona Dempster - Etched water motif plates
©2017 Fiona Dempster - Etched water motif plates
We aimed for a deep etch and achieved this as you can see from the detail photo at the beginning and below.

©2017 Fiona Dempster
Below is a photo of some of the copper residue that was left in the bottom of the etching bath.

©2017 Fiona Dempster
Next step is to clean the shellac off with methylated spirits and the paint off with petrol. That is for another post once the job is done.


  1. looks like a big job with really cool results. love fiona's apron...

  2. love seeing the details of your process!

  3. Gorgeous project! I love to see the process, there's so much to learn from you every time. Thanks for the inspiration.

    Wishing you a wonderful, art-filled week!
    Gaby xo

  4. What happens to the copper residue? Is it useful? Do you have to dispose of it in some safe way?
    Sandy in the UK


Comments are welcomed - it is good to connect with fellow travellers.