Making a Deeply-Bitten Etching Printed as a Relief

Deeply bitten etching printed as a relief

I work almost exclusively doing etching on copper plates. I started out using zinc because it's so much cheaper, but I found that only copper can give clear and clean color. Yellow applied to a zinc plate, for instance, always becomes green as the metal reacts on the ink. I also tend to work a bit impulsively when creating images, which is not a bad thing; one does need to experiment and try things out. But it means I make a lot of images which don't please me and therefore accumulate a stack of expensive copper scraps. My husband has been known to grind down my rejected copper plates for me, using scrapers, sanders and buffers, a process that literally takes hours! Recently a printmaking friend mentioned that she has sometimes used her old plates to do deep biting. This was an idea that really appealed to me, as I am always trying to make my work looser and more abstract, and to invite those wonderful little mistakes and surprises that add a lot of charm to etched plates. By definition, they can't really be planned, so a technique which is a little out of control was just what I felt like I needed. I also had recently read Collagraphs and Mixed-Media Printmaking by Brenda Hartill who does very interesting things with deeply bitten etching plates, so it had been on my mind anyway. After a lot of experimenting, and some pleasing results, I found that this is a technique which really appeals to me. 

You begin simply by applying stop-out varnish right over your old plate. There is no need for de-greasing, cleaning or scraping off of the old image. Very rarely will any of your original marks remain, but if they do, that can be exciting too.

You will be leaving your plate in the acid for hours, so it has to be put in upside down to avoid the air bubbles which can also act as block-out. My husband made me some very nice little holders out of PVC pipe. The plate can not sit on the bottom of the acid tray so does need a way to be suspended in the acid bath.

You will have to cover the back of the plate with tape, adhesive shelf paper or varnish as well, since you won't want the acid to be aggressively biting the plate from both sides!

I use nitric acid for deep biting, which is stronger than ferric (which is what I use for traditional etchings or aquatints). This is a technique with certain risks, as is always true when using acids. So you need to abide by some basic safety measures. This should either be done out-of-doors or under a ventilated hood. The smell of the acid is very toxic. It is best to use a mask and heavy gloves when dealing with the acid. My photo below doesn't conform to the advice I've just given, but as my mother used to say, "do as I say, not as I do." 

I generally do a few plates at the same time, as the process of biting is such a long one. I like using up the tray's entire real estate!

The strength of the acid will determine how long it will take to bite your plate down to where you want it. To begin with I use nitric that is 53% out of the bottle, and then I mix it 1 part acid to 4 parts water. You always put the water in first, and add the acid to the water. With this strong brew of nice new acid, your plate will be very deeply bitten in 12-18 hours. The acid, of course, is weakened as the copper particles dissolve in it. The bluer the mixture, the more diluted it is. I've left plates in a weak mixture for several days at a time, and the plates gently but finally do bite down. You can keep checking on them (carefully) to see if you've gotten what you want. If you are to print them as a relief, they must be bitten about half way through. providing deep valleys which won't hold the ink when you roll it on.

The acid will bite much more quickly on the unprotected areas, but even the parts that you have varnished will begin to break down in unexpected ways.

The first plate I made spent 17 hours in a strong batch of acid and had edges eaten away and holes clear through it. The backing copper that was left is almost as thin as tin foil.

I ink the plate up with a roller as if it were a lino. I don't wipe it at all. Here I'm using my usual Charbonnel #81 black. The valleys do receive some ink occasionally, which can be left, wiped or cleaned out with a Q-tip dipped in solvent.

You then run it through the press with the usual pressure on dampened etching paper. The result is very bold, but it still has a quality which isn't possible with either a woodblock or lino print. You also get a deeply embossed image which can add to its charm. The grays are created from the wiped and treated depressed areas of the plate.

For my own collection of these deeply bitten etchings, I have added color. I like the way it looks with the high contract images. I experimented with chine-collé, water color and ink but in the end settled on hand-coloring with pastel.

These are not like the images I sell in my etsy store, and I don't plan to add them right away. I am enjoying the departure for the time being. If you're interested in seeing more examples, you can visit my art blog.