Re: results from gum printing with the PDN system

From: Katharine Thayer ^lt;[email protected]>
Date: 06/14/05-04:18:59 AM Z
Message-id: <>

Hi Chris,
I can say with authority, having done it some 20 times in my life, that
moving sucks. So I'm in total sympathy, and will understand if you're
quiet for a while. When I moved here in 2001, I was offline for
something like 3 months before I finally got around to hooking
everything up and getting back on. I hadn't thought to unsubscribe from
the list and I had hundred and hundreds and hundreds of messages
waiting, which I never got around to reading.

At any rate, I think you mistook my question for more than it was, a
simple request for the pigments you used.

As I said a while back (about stochastic dots, I think), in my
experience gum operates on the GIGO principle: gum will print whatever
you give it to print. If you give it dots to print, it will print dots;
if you give it continuous tone to print, it will print continuous tone.
So it seems to me that anything that improves the quality of the image
you're printing from will improve the quality of the gum print. No
argument there, and I'm not at all surprised that the PDN system
improves the quality of the image as well as the image to printer color
management, and it seems eminently reasonable to me that this would
improve the quality of the print.

All I'm saying is that the system can only possibly operate within the
limitations of the particular pigments used. I can see how the curve can
help you by backing out excess color if you've got too much, or by
telling you to add more color if you don't have enough. I can see that
as a real benefit of the system. But if you've chosen pigments that
aren't suited to what you're trying to do, or that don't make good color
blends with each other (as a function of the respective reflectance
curves) I don't see how a curve is going to help with that. That's why I
say that I think the pigment choice is the limiting factor in tricolor
printing, although if you start with a good pigment choice, I have no
doubt that PDN can improve the quality of the print.

You chose pigments that should work well for tricolor according to my
tests; PV 19 makes nice enough purples with blue and PY 97 makes nice
clear oranges with PV19 and nice clear greens with blue. There are
other combinations of pigments that simply can't make nice secondary
colors, as a result of how their reflectance curves interact. So I
would say that your success is probably partly due to PDN and partly due
to choosing pigments that work well together. As I said last week, I
think our approaches are complementary, not antagonistic. Good luck with
the move,

Christina Z. Anderson wrote:
> > (Marek wrote) Hi Chris,
> > Lokks like you are happy with your approach here and exited about the
> > results. I will not be able to make it to APIS to see the prints. Would
> > it be possible to look at your results on line( or off line email with
> > scans). What pigments did you use for your tests? IMO color fidelity is
> > the function of pigments used, not so much as tuning each individual
> > separation. I am really curious about your results.
> Hi Marek and Katharine,
> I would agree with both of you to an extent, and have always thought that
> the color fidelity was not only a function of pigment used, but also how
> much pigment in each layer--in other words, too much magenta, it'd be too
> biased to magenta. Along with exposure and development, of course.
> First, forgive me if I don't answer much over the next several weeks for 2
> reasons: I am in the process of packing and moving, and I leave
> Friday.
> I did actually make time to size paper (husband is thinking of killing me),
> which I am doing today amidst the boxes, because there is no way I can make
> generalizations about all this until I get repeatable results. As soon as I
> get a series of prints done with PDN negs I will then send them offlist or
> find a post place online (maybe as Ed has graciously
> allowed me to do in the past).
> This so far is true: I am completely surprised by the positive results I
> got on my first run thru the PDN system with gum. I was not expecting it to
> apply to gum as it does to other processes.
> Two, I am shocked at how the image I got looks like my computer screen
> image. The color fidelity is to the computer screen, if that makes sense.
> I was not expecting this result.
> I've been pondering this laying awake at night and wonder if this
> explanation might fit: if you curve the pigment exactly the dilution and
> exposure at which you are going to use it, then the curve will place the
> color tonally as far as the alt process allows it to go. The separation
> negative then chooses where each color is going to be placed in the image,
> providing the color can actually go there and stay there (be hardened).
> Since the separation negative is curved to match the color, dilution,
> exposure, and process you've chosen, presumably the color will go and harden
> where the negative needs it to.
> Again, I am not saying that other methods don't work. My whole thesis show
> was by my former method. I'll tell you one thing that doesn't make me
> happy: aside from the expense of Pictorico, the material is so sturdy that
> it does not meld into the paper like the Photo Warehouse does, so if there
> are any dips in your paper you'll get blurry exposure from incomplete
> contact. That sure teeed me off. And I am not buying a vacuum frame.
> I'm reprinting some negs now to get more repeatable examples. After that, I
> will have to do things such as switch pigment choices and dilutions,
> exposure time and development time, sit time between coat and exposure,
> etc., and then even go back and derive better curves with my old system to
> see if it is just a curve issue. I know the yellow curve is different than
> magenta and cyanotype, so one size fits all curve for gum is not the case.
> If that is the only thing PDN has taught me about gum, it was worth the $75
> bucks it costs (aside from the fact that I didn't have to write a computer
> program to plot the curves).
> This will take me more than a couple weeks, of course--probably the summer.
> So don't hold your breath.
> My colors I used were Maimeri arylide yellow PY97 and Maimeri Rose Lake
> PV19.
> Chris
Received on Tue Jun 14 11:15:01 2005

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