Kevin O'Brien (kob@paradise.net.nz)
Sat, 13 Mar 1999 20:21:27 +1300
Hi Risa,
My experience with VD printing may be relevant.
1. The contrast was dependent on the coating depth. A thin coat gave the
best tonal range, contrary to what is intuitive. Two coats softens the image
and leads to brush marks.
2. Best contrast if dry and used rapidly
2. It worked best on the surface. Absorbsent paper was no match for
waterproofed lunch wrap (this may be 'Butcher's paper' in the US). Well
sized paper that coated well was to be preferred: it used less sensitiser,
processed easiest and had the longest tonal scale with intense darks.
3. Sunlight gave a good dense VD brown (reddish); Sunlamp more sepia.
4. Exposure: watch for pink tinge in margins to appear or just before it
does in clear areas. Overexposure reduces contrast.
5. Over development (washing) reduces contrast. Two mins sufficient.
6. Fix should be fresh. (2½%) plain hypo.
7. After quick wash blot dry.
7. Negative: highlights shouldn't be too dense. It worked well with a
measured density of 1.35 from film base to highlights. Using an exposure
meter with the neg on the light box there was a reading of 4½ stops
difference. The specular highlights may have had a higher density.
8. Colour can be considerably darkened by heating after work has dried.
A solvent based acrylic spray sold for pastel protection may be suitable.
Another would be the solvent based acrylic resins (Paraloid B67 ?) used by
conservators. It could be matted with diatomacous earth, titanium dioxide or
zinc oxide pigment. There are other acrylic resins readily available and a
supplier like Rohm & Hass would be able to assist. You may need to spray for
an even coating. Some experimentation will be needed. Gelatine has some
reaction with silver but it may work as a coating on top of the acrylic if
an intermediary is needed. Hardened gelatine (post treated with 2% formalin)
might be suitable on its own. Arrowroot is another tradtional size.
If a protective top coat was desired I would try hardened gelatine possibly
with a matting agent. (Printing ink manufacturers a good source of supply of
those.)
Best of luck with your adventuresome project.
Kevin O'Brien
Risa Simone Horowitz <rsh662ta@artslab.usask.ca>
To: alt-photo-process-l@skyway.usask.ca
<alt-photo-process-l@skyway.usask.ca>
Date: Saturday, 13 March 1999 07:42
Subject: VanDyke on alt surfaces (and hello, again)
>Greeting List-folk
>I'm back, and hoping to stick around a bit longer this time (ahhh, the
>wonders of research accounts!)
>
>I am currently trying to figure out how to print and successfully fix
>VanDyke onto flat plaster surfaces. So far, brushing 2 coats of solution
>onto unsealed plaster, with my lights, prints a beautiful soft beige image.
>I set the plaster face up into the sodium thiosulphate bate for 30 seconds,
>and washed, face up, for 30 minutes. The reason I washed face up was for
>fear of scratching the resulting image before hardening. The plaster
>withstands the long washing time.
>
>However, less than 48 hours later, after setting the printed plaster to dry
>in a room with a big window, my suspicions before I started were confirmed:
>the plaster is so absorbent that the solution wasn't fully exposed, nor
>fully fixed or washed: my entire brushed surface is a lovely, even brown :
>full fog in effect.
>
>I also tried one exposure onto plaster sealed with acrylic medium (matte),
>and the brown tone was beautiful, but there was uneven exposure, escessive
>brush marks and the medium could not withstand the wash: it turned to mush
>and looks nasty.
>
>Has anyone ever attempted vandyke's onto plaster? Can anyone off a
>suggestion of what other sealants I could try (without losing the original
>texture of the plaster), and what method of application would be least
>obtrusive? Any other suggestions?
>
>Thanks and HI to all the list people who still remember me
>
>Risa S. Horowitz
>
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