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Re: transfer to metal



Nicholas Yeager wrote:

> I'm trying to get a clean transfer to metal - copper, brass, silver - so
> that I can etch the image directly. I know I can use a Goco screen, but
> would like to get the continuous tone of a direct transfer without the
> screen. I've tried laser, xerox and transfer paper images using heat,
> benzene, and/or acetone but with little success.  I haven't discovered a
> successful process that works. The transfer paper leaves all its coating,
> and the etch covers all the material. Yes, I could cut out the transfer
> image, but often the images are too intricate to accomplish that, and I'd
> like a less labor-intensive method.

First off, all laser printers produce a screen, albeit smaller than
traditional silkscreen, but still there is a halftone dot screen used. The
600 dpi laser prints are capable of approx. 100-line screens, so they are
far less noticible.

Several products are available to take B&W images and produce transfers onto
metal for etching.
Most of these products are designed for circuit-board prototyping. They are
capable of very high resolutions,say 400 dpi, which would give a more
continuous tone quality.

The first is the easiest to use, but the least in terms of ultimate quality.
It a process called Toner Transfer System by DynoArt Designs, Lancaster, CA,
(805)943-4746. They have a huge catalog, but the are not a graphic art
company, so it is filled with stuff I'd NEVER use. This product is a heat
transfer sheet that you can run through a laser printer. It is designed to
be removed, leaving only toner. It works ok, not perfect everytime or
without problems. Factor in this description the fact that I am very
impatient.

The second product I've used is Riston, primarily designed for the same
market--circuit board manufacturing--but has an extremely high quality
potential. It is a photopolymer film product (of various names) that is
laminated to the metal, using the pressure of an etching press, exposed to a
UV lightsource, developed in water, and etched. This is much more labor
intensive, but works very well once you get the negative (sorry I forgot to
mention it was negative working) and the exposure zeroed in. Several other
grad students have used this process to some good effects.  I can't find a
phone number for the company that sells the stuff, but I do have a
URL...http://www.10mb.com/zacryl/
You have to make a negative/positive film for making an image. This is not
too difficult, but can impact the continuous tone look. I've produced
dithered bitmaps from Photoshop that have 600 dpi and make images that are
indistinguishable from true continuous tone images. It takes a lower
contrast image to convert into this bitmapped image, in order to achieve the
final CT image that you desire. You'll have to experiment, or get someone to
produce the negatives for you. There's a book called _Making Digital
Negatives for Contact Printing_ by Dan Burkholder that is very helpful in
this regard.

good luck

Darryl Baird


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