Tips you might use
Photoetching Protocol [v5.0] Photoetching
Special Thanks or Karen for letting us publish her article
here. |
Karen Christians, author M E T A L W E R X 10 Walnut St. Woburn, MA 01801 781/937-3532 |
Photoetching is a process by which a photographic image is transferred onto
a metal surface by either silkscreen or photocopy transfer. With the use
of a mordant (acid), unexposed parts of the photographic surface are eaten
away, thereby producing a 2D image onto a 3D surface.
This process is used by anyone who wishes to have an enhanced surface quality to a piece of artwork. It is noted, that because of the advancements in the microcomputer industry, photoetching has become more widely available as a mass production art form.
The companies listed in the outline and enclosed brochures and reprints are
culminated from my interest in this art process and direct contacts are provided.
Costs can range from a simple kitchen setup ($45) to about $200 from professional
photoetchers (Fell and Son, etched silver metal sheet). Limitations of the
process for home use can vary and I have outlined these plus solutions in
the photocopy transfer etch protocol.
Photoetching either done at home or commercially can be looked at two ways.
At home, you have more creative control on the process, sometimes you can
get happy accidents which move your work in a completely different direction.
However, what you give is what you get from a commercial firm, but consistency
and reliability in a production sense is well worth the time you save.
To understand the basic concept of etching, I quote from Oppi Untracht in
his book Jewelry, 1982
The word etch is derived from Dutch and German words meaning to eat or corrode.
In this process, metal objects are etched by being immersed in an acid solution.
to protect all unetched parts against acid attach, their entire surfaces--front,
edges, and back--are coated with an acid-repelling substance called a resist,
while selected portions on one or more surfaces in a pattern or design are
left exposed to the acids action. Gradually, the acid dissolves and corrodes
these exposed places down to a desired level below the original surface,
while the protected metal remains intact. Any of several separate biting
and digesting menstrua or chemical agents that dissolve metal, or a combination
of them can be used for this purpose depending on the metal being etched.
These etching solutions are composed of inorganic mineral acids, organic
acid solutions, or mixtures of these two. Some acids work best with particular
metals, and some that have little or no effect on particular metals, will
in combinations dissolve them into solution
The Photocopy Transfer Technique
or
PTT
An inexpensive alternative to silkscreen photoetching.
Materials needed: Four plastic tubs, ferric chloride (Radio Shack calls this
PCB Enchant), resist (explained below), duct tape, packing tape large box
of baking soda, water, rubber gloves, large plastic garbage bag, metal, iron,
secondary heat source (hot plate with griddle, electric frying pan or electric
griddle, denatured alcohol, tweezers, paper towels, Sharpie markers (permanent
ink).
Set Up
The acid and rinse baths
Cover a surface with multiple layers of newspaper. Tub 1 is filled about
half way with ferric chloride. The second tub is filled half way with water
and two handfuls of the baking soda. This is your neutralizing bath. The
third tub is filled with water and 1/4 cup of ammonia. The fourth is your
rinse bath. Keep your rubber gloves close by. I use a larger size than my
hands which I can slip in and out of without having to put them on each time.
Place the ferric chloride in one of the tubs. Depending the size of metal
you are etching use a tub size accordingly. For small pieces, I cover the
back of the metal with packing tape and cover the sides. Remember, any exposed
parts will etch away! Suspend the piece to be etched METAL SIDE DOWN and
submersed mid way in the acid bath. Do not let the metal sit on the bottom
of the tub. Take a long piece of duct tape and place the backside of your
piece to the sticky side of the tape. Drape the tape from each side of the
tub suspending your metal in the acid bath. With the PTT, you will need to
check your image periodically for acid bite. If you find portions of your
image being eaten away, rinse first in the neutralizing bath and then in
the rinse bath. Rinse thoroughly and then dry completely. Beef up your image
with the Sharpie Marker.
Etching can take anywhere from 1 and half hours to up to six or even overnight, depending on the quality of your acid bath. Checking periodically will keep your image tight and sharp.
Image Preparation
Any high quality, high contrast image can be used. The graphics found in
the Dover clip art books are especially good, but a good quality photocopy
of any black and white photograph works equally as well.
The photocopy transfer technique is somewhat dependent on the toner found
used by various photocopiers; keep persisting until you find one that works.
First photocopy your image onto regular paper. Adjust size, light/dark contrast
on paper before you print onto the transparency film. For best results use
the IBM PM 2500 . Be sure to make at least three copies
on the transparency film in case the toner transfer does not take.
Metal Preparation
Clean copper or brass with Penny Bright and then Scotch brite which gives
the metal a tooth and aids in the image transfer.
Metal gauges can very from 20 (light etch) to 14 (heavy etch).
The Transfer Process
Have an iron set on high (linen setting) and an electric griddle or hot plate
to med. high heat.
You should have a paper towel between the griddle surface and your metal
to keep the metal from sliding and marring the griddle.
Clean the image/toner side of your transfer and your metal with denatured
alcohol. While the metal is still wet with the alcohol, press the
image down onto the metal and make a good seal.
With another paper towel, place it over your transfer acetate and place the
iron over that. Do not let the alcohol dry out and the image lift
before you iron.
Let the whole thing "cook" for about 1 and half minutes and then take the
iron off.
Try to leave a tiny corner of the acetate folded up so you can check the
result easily. A couple of dots photocopied onto your acetate can serve as
a test area.
If your metal is too hot, the toner will melt and will result as a smeared
image. If your metal is too cold, the transfer will not take. This part takes
practice and knowledge of your iron and griddle temperature.
Check the toner transfer by gently lifting up the acetate with a tweezer
and seeing if the image is clear and has transferred. Keep a burnisher close
by to help in some areas.
Even if you have a little toner on your acetate left but with a clear image
on your metal, that is good enough. Sometimes you will see some area where
the toner has not adhered perfectly, and the result will be a bloom. This
can be beefed up with the Sharpie Marker and returned to the acid bath.
The toner can be burned off with a torch after etching.
Resists
An acid resist is anything that will resist or repel the biting action of
the acid. Traditionally asphaltum has been used which works fine but can
be messy to remove. Zacryl polymer resists are great and work very well.
After your image has been transferred, take the reverse side of your metal
and pour a thin stream of Zacryl and cover the entire side. Zacryl is completely
non toxic and is easily removed with Windex but holds up to either ferric
chloride or nitric.
After a thin coating has been applied, let the Zacryl dry completely before
immersing into the acid bath.
Zacryl comes in two forms. One is the blue soft ground resist, the other
is a green hard ground resist called Stop Out. This is also good for touch
ups and can be used like the resist pens.
Other resists can be duct tape, finger nail polish, melted wax, vinyl lettering,
etc.
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Couple of notes:
Photocopy machines: Some photocopiers are pickier than others when using
the PPM 2500 acetate. If your photocopier needs a sensing strip, which is
a white strip on one side, then look for the same brand with the sensing
strip.
Most commercial photocopiers are designed for speed with the barest amount of toner applied to the paper. It is important to tweak and experiment for the highest slather of toner without comprimising the photographic quality.
Alcohol: Some manufacturers of toner can take full denatured alcohol. Others
will bleed and if this happens, use isopropyl and water. First go 50/50 and
if this is too strong, dilute with more water. Keeping the acetate and the
metal wet when you lay the acetate down is key. Run your hand and "squeege"
out the bubbles.
For Laser Printers: You can do a direct paper to
metal transfer. No acetate is needed.
1) Clean the metal in the same way as described in the regular protocols.
Use a 400 sandpaper for final finish and clean with alcohol. Iron toner side
down directly to the metal. DO NOT WET PAPER! This is dry proceedure. Iron
for about 2 minutes, high heat, but check your iron first. They all vary
in temperature. No griddle or heat source is needed underneath. Top heat
is plenty.
2) When you feel the paper sticking to the metal, DO NOT PULL AWAY. Let the
metal cool completely. Immerse in tepid water for 10-15 minutes. Remove from
water and GENTLY begin rubbing the paper away. Your image should remain.
Etch as usual.
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