Thursday, January 7, 2010


Pouched Coral fern, bracken, club moss.

We pulled over to the side of the road near Broken Head to get these photos for etching. I discovered later that week the price to pay as baby ticks had by then burrowed deep into my person!

Once I stopped itching, the images were 'thresholded' and 'inverted' in photoshop reducing them to strong black and white tones only which a choice of positive or negative.
Then they were photocopied on to Press n Peel computer circuit board paper. An iron at high heat transferred them onto my super clean (scotchbrite, detergent ammonia, meths) copper and silver sheet (0.5- 0.7mm). This can be tricky as I am no good at ironing and the images sometimes only partially transfer. I think the humidity also has a negative impact. Some I patched up with paint pen circuit board marker. Others I re-did.

Then I prepared a nitric acid etch bath in pyrex dish. Very carefully. With gloves. Actually I had some I'd already mixed which can be used again and again. I was intending to use ferric chloride and ferric nitrate but discovered that I'd left some of the equipment at college. You need more stuff for the safer chems. It was good in the end as nitric is super fast although incredibly evil and I had previously thought it did not work as well with the press n peel. But it does.

The pieces were immersed for up to 20mins. I watched carefully through my safety goggles and tried not to breathe in the vicinity. Doing yoga in an adjacent room proved misguided as traces of fumes wafted my way making me wonder what the hell was happening in the acid bath instead of being calmly aware of the present moment.

The bubbles forming on the surface of the metal were brushed gently with a sulphur crested cockatoo feather. I couldn't help thinking that Phillip Adams would have approved as he refers to the white birds as "rats of the air". Poor cockatoos. I apologised to the feather (one of the only soft things that won't dissolve in nitric) and got on with the job. The bath accelerated and at the end I contemplated dilution as one piece of copper was fairly frothing and spongy slag forming so quickly that it was dislodging the resist. Enough!

Then the pieces were neutralised in soda and cleaned with scotch brite and fine brass brush. I patinated them with some Jax blackener. It does not really work well on copper but when I woke up this morning I found that verdigris had grown in the coral fern etch overnight! Magical chemicals!

I'm not sure how I will use them but made a funny little brooch using a silver coral fern positive etch and impressing vinyl onto a negative bracken fern etch. The copper one that got out of control in the bath and etched at various depth as the resist was dislodged created an interesting 3d surface. I was thinking of convergent evolutions (coral/coral fern) and fossils.

I like the etching method and also making impressions from etching as unlike the other methods we have tried with silicone and wax and clay, it allows me to reduce the scale. I am doing more experiments with the etchign and will try to multilayer it, like the multilayers of the wallum.


  1. thanks for all the detail on the process. Love the verdigris :)

  2. Hi Rebecca,
    fascinating reading about this process - incredibly detailed stages, part science lab, part unpredictable...
    great images and results,

  3. thanks for the encouragement people! Struggling at the moment with the hot weather to get into the studio but you have spurred me on!