The toxic nature of the chemicals, solvents and acids used in traditional etching and require the use of expensive equipment to make the print studio into a safe working environment. Traditional methods of etching have become institutionalised into current practice if there is to be a transition into using less toxic methods it will require behavioural change on the part of current artist’s printmakers. There is anecdotal evidence that even in print centres and studios committed to safe printmaking that members whose main practice is etching have a preference for acid as a mordant over alternatives such as saline sulphate etching.
In previous research undertaken into safe etching techniques at, the Regional Print Centre in Wrexham, and the Print Centre in Leinster in the Irish Republic, it was found that saline sulphate etching could be considered as an alternative to but not a replacement for acid etching. Saline sulphate was considered to be an unstable process in that it is not possible to guarantee consistent or predictable results. There are also issues about the safe disposal of the spent mordant. The objectives of that research were to explore the use of less-toxic etching techniques as a potential replacement for traditional acid etching in the learning environment and the artist’s home/studio. With the outcomes being to establish an ongoing research ethos at the Regional Print Centre to explore, research and expand the use of less toxic printmaking techniques.
The current proposal follows on from the previous research and the interest of the Print Centre to form a research partnership with Glyndwr University. One of the methods explored was that of galvanic etching or electro etching. We noted that despite all the interest in safe etching over the last fifteen-years or so, there has been little take up of electrical etching which is probably the safest and most environmentally friendly of all the alternatives to acid etching.
Electrical / Galvanic Etching
A patent was granted to Thomas Spencer and John Wilson in 1840 for ‘engraving metals by voltaic electricity’. Whilst experimenting with galvanic cells using copper and zinc plates suspended in copper sulphate and sulphuric acid they found that copper was deposited on the cathode or negative metal and that zinc anode was etched (diagram 1). Spencer went on to use this process to plate small objects and to make printing plates
If two plates of copper are placed facing each other in a solution of copper sulphate (the electrolyte) and connected to a direct current power supply, the current will flow through the electrolyte from one plate to the other. The copper sulphate contains positive copper ions and negative sulphate ions (diagram 2). When the power is switched on, the positive ions in the electrolyte are attracted to the negative plate, and the negative ions are attracted to the positive plate. The negative sulphate ions are attracted to any unprotected areas of the positive (anode) plate and react with, oxidise and corrode the exposed surface of the metal. The positive copper ions are attracted to the negative (cathode) plate and adhere to it.
The etching process is very simple. The plate to be etched is painted over with a protective ground that is drawn into with an etching needle. This plate is attached to the anode (+) and placed in the container with the electrolyte facing parallel with a clean plate that is attached to the cathode (-) with a space of between 5 to 10 centimetres between the cathode and anode.
In this process there are no concerns about disposal of the copper sulphate because the positive copper ions attach themselves as copper to the cathode plate and the same amount of copper is removed from the anode plate and the electrolyte maintains its original concentration. The electrolyte can be used indefinitely as there is no change to its state no matter how often it is used. The stability of the electrolyte allows for a more accurate calculation of the bite time than with acids or saline sulphate etching. Some of the advantages of using electro etching are that the stability of the electrolyte means that the printmakers can produce a consistent bite, no toxic gasses are produced, there are no waste products or any sediment build up at the bottom of the tank Crujera, (2010).
Current Literature on Electrical / Galvanic Etching
In the literature we have identified four writers who are exploring the use of electrical etching these are, Green, (2011), Crujera, (2010), Omri and Marion Behr (1993) and Semenoff, N and Bader L. (1998). The methods used by these writers are modern versions of those used in the nineteenth century by Thomas Spencer. They all use the salts of the metal being etched as an electrolyte in varying degrees of solution.
Green and Berhr use the same type of metal for both the anode and the cathode. They all concentrate on using the traditional metals for plate making i.e. Copper and zinc, for etching copper sulphate is used as an electrolyte for etching copper and zinc sulphate for etching zinc. None of them mentions aluminium as a possible matrix. In personal correspondence from Alfonso Cujera he explains that he had tried etching aluminium using aluminium sulphate as an electrolyte but that this had been unsuccessful. Our own experiments with aluminium and aluminium sulphate were also unsuccessful. While searching the literature on corrosion we found a paper by A. Pollit and Ernest Benn in which they describe three types of corrosion:
- Auto corrosion
- Contact corrosion
- Externally induced corrosion
It is the third type of corrosion the externally induced that is of interest to us. This is said to be the result of the passage through the metal of an externally induced current whilst it is in contact with an electrolyte. Corrosion results when the direction of the current makes the metal act as an anode. If the current flows in the opposite direction, from the electrolyte to the metal the metal acts as a cathode and is protected from corrosion. This process is also poetically described as the sacrificial anode because the anode corrodes and protects the cathode from corrosion. Contact corrosion follows a similar process but without the added the externally induced current. Sir Humphry David first described the sacrificial anode phenomenon, and recommended that zinc strips be attached to the copper hulls of sailing ships to prevent their corrosion. The seawater acts as the electrolyte, the copper having a higher electrical potential becomes the cathode in the cell and the zinc the sacrificial anode. Both contact and externally induced corrosion can be described as dissimilar metal corrosion. Crujera (2010) in his paper describes that earlier experiments into electro etching with sodium chloride had failed. We believe at that time he was using aluminium for both the cathode and anode. An experiment was set up using sodium chloride as an electrolyte, aluminium as the anode and stainless steel as cathode, the result was a successfully etched plate. An e-mail was sent to Alfonso Cujera informing him of our success. He has gone on to replicate our findings and put us in contact with Francisco Hermandez-Chavaria a teacher at Costa Rica University who has also been carrying out experimental work in this area. This correspondence is ongoing and is proving to be a valuable international collaboration. Nearer to home, we have received some help from Professor Peter Excell of Glyndwr University. We were experiencing the build up of gelatinous goo in the saline electrolyte that appeared to slow down the etching process. From our experience with saline sulphate etching we thought this might be aluminium hydroxide. He was able to confirm our suspicions and suggested that we acidify the electrolyte. We ran a successful experiment using white vinegar. The vinegar provides enough acidification to disperse the aluminium hydroxide without interacting with the aluminium.
Aluminium is readily available, cheap, light and easy to handle. A 2 x 1.5 sheet costs around £30.00 to £40.00. The same sized sheet of copper or zinc would be well out of range for most studios or individuals to contemplate purchasing. Aluminium etches in a very different way to other metals. With zinc and copper to achieve tonal graduations a separate process called aquatint has to be applied to the plate. This requires the use of resin dust that is both carcinogenic and highly flammable. The structure of aluminium means that it etches progressively and has a natural aquatint giving a range of tones from light grey to black.
To explore and develop through an action research project the use of electro etching for its potential as an alternative for traditional acid etching in the learning environment and the artist’s home studio.
- To develop an action research programme by introducing printmakers to electro etching through a series of workshops and to elicit feedback of their use and development of the processes through further meetings and questionnaires.
- To establish an ongoing action research programme to explore, research, develop and promote electro etching as a technique and methodology for use in learning environments and the artist’s home studio.
- To establish whether or not electro etching methods are a viable alternative or replacement for traditional acid etching.
- To run a series of workshops based on learning from the action research programme.
- To publish research findings and feedback through a weekly blog and magazine articles.
The research model that was identified as best fit for unleashing learning was Action Research or Collaborative Enquiry using methods based on research ‘with’ rather than on people. The focus of action research is on participants being actively involved in the research and research decisions as full participants and co- designers and researchers ‘Action research begins from where people are’. It is real world situations that are the area of interest and focus (McNiff and Whitehead (2010) p.10). Rather than having a cause and effect based traditional scientific hypothesis they suggest that research tends to be based on working hunches such as ‘I wonder what would happen if we…?’ (ibid p.12)
Printmakers usually start out as artists first and identify print as their media of choice later after being introduced to it through the work of other artists. Skills are learned through workshops or self taught. If the techniques they have learned give them the results they want, they see no reason for change. The traditional methods of printmaking have become institutionalised into current practice therefore the transition to using alternative processes will require behavioural change on the part of many current printmakers. The research group will be open to all members of the Regional Print Centre in Wrexham and others who attend the workshops.
Interest in hosting workshops have been expressed by:
Regional Print Centre Wrexham
Leinster Print Centre Republic of Ireland.
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