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Low-Toxic Etching

The Edinburgh Etch

The Haldane Print Workshop – Low Toxic Intaglio Etching

The Edinburgh Etch – A safer way to etch

Ferric Chloride has long been known to be a highly reliable and consistent substance for etching intaglio plates but was often put aside in place of Nitric Acid due to the impractically slow speed of the etch. Ferric Chloride does have great benefits over Nitric Acid, as it doesn’t emit toxic vapours (even during the etching process), is much less aggressive when in contact with skin, and doesn’t react violently if spilled, but due to its slow speed it has somewhat been kept in the shadows.
That is until the invention of The Edinburgh Etch….

The Edinburgh Etch, which was invented by Friedhard Kiekeben at The Edinburgh Printmakers Workshop in 1997, significantly increases the etching speed and has made Ferric Chloride a viable and exciting option for the modern printmaking workshop. The slow speed of plain Ferric Chloride is mainly caused by a build-up of sediment in the etched lines, which prevents any further etching to be achieved in those areas and results in very long etching times. The Edinburgh Etch speeds things up by using Citric Acid as a catalyst, which increases the efficiency of the chemical reaction by dissolving the sediment before it can build up.
To help this process work even more efficiently a Vertical Dip Tank can be used to suspend the plate in the solution while it is etching, which allows the sediment to fall out of the etched areas and then be dissolved without causing any obstruction. The design of these tanks also makes this technique extremely compact, without losing the ability to etch large plates, and as they have lids the solution doesn’t evaporate and so lasts for a long time.

Of course there are still risks with this technique and the use of gloves, goggles, and aprons is mandatory, but it is a great step forward in improving the safety, reducing the environmental impact, and minimising the space requirements normally associated with acid etching.

More information, email David Farrar, Printmaking Technician, Design, Glasgow School of Art

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