Editing Etching (section)

===Nontoxic etching===
{{History of printing}}
Growing concerns about the health effects of acids and solvents<ref>{{cite web |url=http://web.princeton.edu/sites/ehs/artsafety/sec13.htm |title=Welcome to the Office of Environmental Health and Safety &#124; Office of Environmental Health and Safety |publisher=Web.princeton.edu |access-date=2015-08-11 |archive-url= https://web.archive.org/web/20120826014445/http://web.princeton.edu/sites/ehs/artsafety/sec13.htm |archive-date=2012-08-26 |url-status=dead }}</ref><ref>{{cite web|url = http://www.chicagoartistsresource.org/node/9287|title = Intaglio Health and Safety: Overview|first1 = Angela|last1= Babin|first2= Michael|last2= McCann |archive-url= https://web.archive.org/web/20120825165930/http://www.chicagoartistsresource.org/node/9287 |archive-date=August 25, 2012 |website = Chicago Artists Resource}}</ref> led to the development of less toxic etching methods<ref>{{cite web|url=http://www.greenart.info/galvetch/etchtabl.htm |title=Traditional intaglio printmaking methods, their health hazards, new non-toxic substitutes |publisher=Greenart.info |date=2013-03-14 |access-date=2015-08-11}}</ref> in the late 20th century. An early innovation was the use of floor wax as a hard ground for coating the plate. Others, such as printmakers Mark Zaffron and Keith Howard, developed systems using [[acrylic polymer]]s as a ground and [[ferric chloride]] for etching. The polymers are removed with [[sodium carbonate]] (washing soda) solution, rather than solvents. When used for etching, ferric chloride does not produce a corrosive gas, as acids do, thus eliminating another danger of traditional etching.

The traditional aquatint, which uses either powdered rosin or enamel spray paint, is replaced with an airbrush application of the acrylic polymer hard ground. Again, no solvents are needed beyond the soda ash solution, though a ventilation hood is needed due to acrylic particulates from the air brush spray.

The traditional soft ground, requiring solvents for removal from the plate, is replaced with water-based relief printing ink. The ink receives impressions like traditional soft ground, resists the ferric chloride etchant, yet can be cleaned up with warm water and either soda ash solution or ammonia.

Anodic etching has been used in industrial processes for over a century. The etching power is a source of direct current. The item to be etched (anode) is connected to its positive pole. A receiver plate (cathode) is connected to its negative pole. Both, spaced slightly apart, are immersed in a suitable aqueous solution of a suitable electrolyte. The current pushes the metal out from the anode into solution and deposits it as metal on the cathode. Shortly before 1990, two groups working independently<ref>{{Citation | last1 = Behr | first1 = Marion | last2 = Behr | first2 = Omri | title = Environmentally safe Etching | journal = Chemtech | volume = 21 | issue = 4 | pages = 210 | year = 1991}}</ref><ref>{{cite journal|last1=Nick|first1=Semenoff|last2=Christof|first2=C.|title=Using Dry Copier Toners in Intaglio and Electro-Etching of metal Plates|journal=Leonardo|date=1999|volume=24|issue=4|pages=389–394|doi=10.2307/1575513|publisher=MIT Press|jstor=1575513|s2cid=191386942}}</ref> developed different ways of applying it to creating intaglio printing plates.

In the patented<ref>{{cite patent | inventor1-last = Behr | inventor1-first = Marion | inventor2-last = Behr | inventor2-first = Omri | fdate = 11990-10-31 | pubdate = 1992-04-07 | title =Electrolytic etching process and apparatus therefor | country= US | number = 5102520 }}. The voltage should be adjustable to operate accurately within a rather narrow voltage range, such that the minimum voltage shall be at least that of the ionization potential of the metal object in the electrolyte chosen and the maximum shall not substantially exceed the sum of the decomposition voltage of the aqueous electrolyte and the over-voltage of the cathode selected.</ref><ref>{{cite patent | inventor1-last = Behr | inventor1-first = Omri | inventor2-last = Behr | inventor2-first = Marion | fdate = 1992-11-05 | pubdate = 1992-05-12 | title = Method and apparatus for producing etched plates for graphic printing | country= US | number =5112453}}</ref> Electroetch system, invented by Marion and Omri Behr, in contrast to certain nontoxic etching methods, an etched plate can be reworked as often as the artist desires<ref>{{Citation | last1 = Behr | first1 = Marion | last2 = Behr | first2 = Omri | title = Etching and Tone Creation Using Low-Voltage Anodic Electrolysis | journal = Leonardo | volume = 26 | issue = #1 | pages = 53– | year = 1993 | doi=10.2307/1575781| jstor = 1575781 | s2cid = 100716855 }}</ref><ref>{{Citation | last = Behr | first = Marion | title = Electroetch, a safe etching system | journal = Printmaking Today | volume = 3 | issue = #1 | pages = 18– | year = 1993 }}</ref><ref>{{Citation | last = Behr | first = Marion | title = Electroetch II | journal = Printmaking Today | volume = 4 | issue = #4 | pages = 24– | year = 1995}}</ref><ref>{{Citation | last1 = Behr | first1 = Marion | last2 = Behr | first2 = Omri | title = Setting the record straight | journal = Printmaking Today | volume = 7 | issue = 4 | pages = 31–32 | year = 1998 }}</ref> The system uses voltages below 2 volts which exposes the uneven metal crystals in the etched areas resulting in superior ink retention and printed image appearance of quality equivalent to traditional acid methods. With polarity reversed the low voltage provides a simpler method of making mezzotint plates as well as the "steel facing"<ref>{{Citation | last = Behr | first = Omri | title = An improved method for steelfacing copper etching plates | journal = Leonardo | volume = 30 | issue = #1 | pages = 47–48 | year = 1997| doi = 10.2307/1576375 | jstor = 1576375 | publisher = The MIT Press | s2cid = 139028601 }}</ref> copper plates.

Some of the earliest printmaking workshops experimenting with, developing and promoting nontoxic techniques include Grafisk Eksperimentarium, in Copenhagen, Denmark, Edinburgh Printmakers, in Scotland, and [[New Grounds Print Workshop]], in Albuquerque, New Mexico.