Looks like David sent a personal letter to the whole list by accident.
Anyhow, some of the points will be of interest to a lot of people.
>
>I also wanted to mention a couple of things (in case you're taking notes
>for your *next* edition).
>
>I have been working with the Arches Platine for a few months now. I
>double coat (7Pd:1Pt), let each coat dry overnight, develop in room
>temperature potassium oxalate with sodium dichromate as the contrast
>agent, and finally a bath in liquitex gloss medium diluted 1:12 with water.
>..kind of breaks a lot of rules, eh?
>
>o.k. one by one...
>
>I double coat because I have found in every experiment I have done, on
>every paper I have tried, that double coating yields a deeper black.
This sounds like a pretty good reason to me;-)
>
>After a lot of experimentation I have found that I get the best results
>by letting the paper dry overnight. Contrary to common wisdon, this has
>not resulted in a sunken/flat image. It does reduce grain, and give
>richer blacks however.
>
>I use room temperature potassium oxalate. Yes, I know it's a
>super-saturated solution, but I haven't had any trouble with crystals. I
>did note (I think - I will have to double check) that you mention that
>Ammonium citrate is also used in a super-saturated solution, which is not
>the case.
>
>I am using Sodium Dichromate as a contrast agent. It works great. I
>noticed that you mention Potassium Dichromate and bleaching. I have no
>problems with bleaching using the "Sodium" Dichromate, and it cost less
>than Potassium Dichromate.
This would depend on where you get it and the grade you order. I haven't
bought any sodium dichromate for years because getting the AR quality here
was much more expensive than the other stuff.
>
>Another benefit to using the dichromate is the ability to do "local"
>development using different contrast grades of developer. Remember you
>heard it here first! - or maybe not... :)
>
>For example I have a negative of a large rock on the sea shore. It was a
>long exposure just as the sun had dipped below the horizon. It has a lot
>of overall contrast, but not a lot of local contrast. The sky above the
>horizon is a very high value. If I print to get the clouds, and even a
>faint edge to the print, then the rock is too dark. So, I print for the
>sky, and then use a higher contrast developer on the rock with a q-tip.
>
>The higher contrast developer has two benefits in this case. First, it
>increases the local contrast in the rock, and second, it's "speed" is
>slower so the rock is not as dark as it would have been. Once the rock is
>developed, I then immerse the whole print in the regular developer. The
>rock does not change as a result of being immersed in the regular
>developer.
>
>I can also go the other way. If I need to have an area print darker, I
>can locally devlop with a lower contrast grade of developer, which seems
>to have more speed, thus making that area darker (of course, it also has
>lower contrast, so there's no free lunch).
Indeed, I think this is the first time I hear about this method. Anyone
else has tried that with success out there?
>
>Finally, I use a dilute liquitex bath (after the print has dried). This
>bath doesn't really add any perceivable gloss, but it does nake the
>blacks richer, and therefore also seems to increase contrast slightly.
>As fine art painters feel that this material is "safe" to use (with
>regard to longevity, yellowing, etc.) on their paintings, I feel
>comfortable usinging it on my prints.
Bad news: Liquitex and other brands of acrylic dispersion gels may not be
very permanent. Read on.
"The discoloration can occur in any brand of acrylic media or gel, but is
most noticeable in the unpigmented gels, matte, and gloss media. It is the
result of a detrimental interaction between the support and the media"
This, from p. 381 in James Hamm et al, "The discoloration of Acrylic
Dispersion Media", _Saving the Twentieth Century: The Conservation of
Modern Materials; Sauvegarder le XXe siecle: la conservation des materiaux
modernes_ Proceedings of a conference, Sept. 1991, Canadian Conservation
Institute, Ottawa, pp. 381-392.
I would try gelatin as a substitute, fully hardened afterwards. It
certainly won't be as convenient to use, of course, and platinum does not
necessarily like gelatin. Mike Ware may have something to say about this.
>
>Right now I am working on preparing materials for a platinum printing
>workshop I am giving in January, however, once I get a chance I will try
>to print a few test samples to send your way so that you can judge for
>yourself.
I always enjoy receiving samples for my museum collection here and as
potential candidates for use in my books and lectures. I'll send you
instructions to help me avoid hassles with Customs, etc.
Luis Nadeau
>
>Best wishes for the holiday season,
ditto
LN
>David Fokos