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List
of safety rules in using direct current power supplies and batteries, for
etching printing plates electrolyically. Extract from GREEN
PRINTS by Cedric Green published by Ecotech Design, Sheffield, UK. -
a handbook on new methods for non-toxic intaglio etching and metal plate
printmaking, featuring the technique of Galv-Etch,
a modern development of the 19th century electrolytic technique of Electro-Etching,
and introducing Fractint and other new alternative
methods avoiding the use of solvents and chemicals harmful to health and
to the environment.
SAFETY
PRECAUTIONS
The list of basic precautions listed below
are mostly ones that an experienced printmaker who uses electrical equipment
of any kind will know, but as this is all about safe printmaking, they
are repeated here together with some that are specific to galv-etch using
the equipment I have described.
- The area where you do galv-etch
should be free of solvent fumes of any kind (as the whole working space
should be). Make sure all your electrical connections from battery charger
to the mains are correctly made and that the whole system is protected
by a mains switch which is easily accessible. If you are using a time
switch on the mains input, it should be switched.
- On the low voltage direct current output from the power
supply (battery charger) you will usually find a pair of large crocodile
clips, the positive on a red wire, negative on a black wire. While the
system is not in use clip these both to an insulating strip of plastic
or card so that they cannot touch accidentally. If you make any new
leads always use wiring of the same type and weight, and make all joints
mechanically with screwed junctions, not with soldered joints.
- When you are preparing to start a galv-etch, put the
plate and cradle or connecting bar into the electrolyte and make all
the connections before switching on. Do not make or unclip any connection
while the current is flowing or you may create a spark - if you have
to stop the etch quickly, turn off at the mains switch.
- Take great care using a flat tray with a cathode in
the form of a grid of wires, and do not try to control the current by
lowering the grid into the electrolyte. If you are using a vertical
tank and lowering the cathode into the electrolyte to control the resistance,
start off with it just touching the surface and clipped to the side,
switch on and then unclip it, lowering it slowly while watching the
ammeter, and re-clip it when the right level is reached. To avoid an
uneven depth of etch, check that the immersed part of the cathode is
opposite the centre of the plate.
- If the power supply is overloaded, switch off quickly
and first check that you don't have a short circuit somewhere - a plate
bar strap touching a grid support for instance. If not, use another
method like a vertical tank, a diluted electrolyte, or use a different
power supply like a rechargeable battery or solar cell array, or include
a resistance like a 12 volt lamp in series in the circuit, or a control
box as (shown elsewhere). Note that adding
a resistance reduces the voltage and produces a more gentle galv-etch
which takes much longer.
- If you use a lead acid rechargeable battery (12 volt
car or 6 volt motor cycle battery) you must have very heavy duty connecting
wires - I recommend car jump leads to be on the safe side. Wire a mains
switch into the positive (red) lead. Make all the connections with the
crocodile clips first, then switch on, and keep an eye on the progress
of the etch. Plating or galvanoplasty puts a much heavier load on the
power supply, partly because the cathode - this time the plate on which
you will be depositing metal (-ve) - will probably have a large conducting
surface, and the anode (+ve) must be solid and not a grid.
- If the rate of etch seems too fast or vigorous, include
a resistance like a 12 volt halogen lamp in series in the circuit. Mount
the lamp in its socket with a two-way switch to cut it out if you don't
need it. I have made a little control box with a 12 volt 50 watt lamp,
a 2-way switch, and a 50 watt, 5 ohm variable resistance, wired in series
on the positive lead from the power supply, which can be instantly switched
in if the ammeter on the power supply indicates an overload, and then
used to regulate the voltage (shown elswhere).
Note that this resistance in series reduces the voltage and the amperage,
and in consequence a longer time is required for the galv-etch, which
may be necessary if you are using traditional soft ground or producing
textures by pressing oily materials onto a bare plate.
- At any time that your hands might be in contact with
the electrolyte, wear thin waterproof gloves because the sulphate solutions
are slightly acidic, and in particular with zinc sulphate, take care
to avoid any contact with skin or eyes, and keep all the solutions out
of the reach of children Store it in a safe place, well labelled to
avoid anyone having an accident or drinking it, as it is a clear liquid.
No special precautions are required for copper sulphate, except perhaps
wearing gloves to protect the skin from drying out and staining blue.
- Before lifting a grid cathode or the etched plate out
of the galv-etch tray, make sure the current is off - cut by the timeswitch
or off at the mains. If using a battery charger or mains rectified power
supply, when you have finished work, switch off the mains supply to
the unit. If you are using a battery, remove the leads from the terminals.
(TOP).
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Detail
of "Nine Variations on a back" - galv-etched and fractinted zinc plate
proofed in 4 colours from single plate |
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