Re: Gum Curves, new topic please????

Chris,

I don't think we should be talking about religion and politics on the
list either, but in this case I believe there is an important
relationship between conditions that you and Dan Burkholder
photographed and political decisions made in the past that make the
comments appropriate. Obviously some people agree with me on this,
while others don't. But as Philip Murphy noted, the thread was
clearly labeled Off-Topic so there would be no reason for anyone to
have to wade through the messages if they don't want to be bothered
by political crap. Just say no and move on.

As for the carbon print, I simply forgot about it. I have been
incredibly busy trying to finish out the semester, have also had to
make a slew of medical medical appointments, we had orders for a
whole bunch of UlF filmholders, and I am trying to get organized to
go to APUG in Toronto on Wednesday, where I am doing two separate
process workshops/demos, one on carbon, which was planned from way
back, and another on Pt./Pd. which I agreed to do at the last minute
when the person who was supposed to do it had to cancel because of
illness.

In any event I will look around today and try to find a suitable
carbon print to send you.

Sandy

>Good morning,
>
>I'm late in replying to a post of yours Yves, so forgive. I have to spend
>too much time wading through political crap, which to me is anaethema to the
>list. I get enough of it on the news. My parents raised me not to talk
>about religion and politics in mixed company--where does it get us? My
>mother was an aetheist, my father a believer, hence the reason to keep the
>peace. AND, I took after my father in case anyone gives a rat's ass.
>
>SO I thought I would open controversy back into photography and give people
>something more "alt" to argue about. Gees.
>
>In reference to curves, I thought of summing it up this way, Yves:
>
>"No curve can transcend the limits of the process, but sometimes what is
>termed "the limits of the process" can, in fact, just be an improper curve."
>
>Whether exhibited in an improper density range of an analog negative or an
>improperly formulated digital negative, I think this has forever been true
>with gum.
>
>All a perfect digital curve will do for you in gum is make it a hell of a
>lot easier to get a good print--you find your standard printing time to
>harden the gum, your color negative that you will use to hold back enough
>light to give you paper white, and then the curve to give you the range of
>tones from black to white. I find then that gum becomes very predictable
>and not the capricious process it is always termed.
>
>NOW, all of that said, people have been getting gorgeous gum prints for
>centuries without a perfect digital curve, using analog negatives, paper
>negatives, imagesetter negs, lith negs, toilet paper, ...I was just copy
>sliding Bea Nettles' quik prints from Flamingo in the Dark and I STILL find
>her work evocative and gorgeous and all of it was done before a home output
>digital neg existed. My whole thesis, for instance, was done pre-PDN, but I
>did use a curve. But what I found when I went back and
>reprinted those same images with a custom derived curve suited to each color
>was WOW, the image was better, more accurately color balanced to
>the original, you name it. It was a revelation.
>
>BUT, if all I taught in my alt class was how to produce perfect tricolor
>gums, what's the point?? That is only a starting point to understanding the
>gum process, and then springboarding off of that to produce imperfect
>prints, so to speak, just as nowadays you can see the proliferation of
>scratched negatives, blur, dark prints, and all those experimental kinds of
>things that people are doing with analog photography. I feel that will be
>the style of the early 21st century--this beautiful darkness.
>
>I have just sent Loris Medici offlist (my website STILL under construction)
>an image I have been working on so in time he will post it. Seems Sandy is
>too busy talking politics to send me a carbon print (that was a big HINT
>Sandy) so I took it upon myself to one-up Sandy--I have a large platinum
>print of a New Orleans subject called Mobile Home. I scanned said print.
>That is why only part of the image is there because it is too big to fit on
>my flatbed. Unfortunately, there is no comparison between carbon processes,
>the original reason for the experiment. The original quest was to see if a
>one coat gum could in fact rival the detail and tonal range of a carbon
>transfer print, etc. etc.
>
>This is my explanation for the image:
>
>ALL images have been scanned and not dinked with at all. No sharpening, no
>tweaking, nothing. As is.
>
>I felt comparing gum to a platinum print with its gorgeous tonality and
>smooth transition would be the ultimate insult to gum, even more than
>carbon.
>
>What I then proceeded to do was take 1 g. carbon powdered pigment to 100ml
>of gum--Dave Rose's formula, and do a print. Too weak. Then I upped it to
>2g. Still too weak. Then I upped it to 3g. Fine. Then I developed a
>curve based on 3g carbon powdered pigment to 100ml gum.
>
>I have labeled each image on the composite so it should be explanatory.
>
>I also included on there the image of gum printed on unhardened gelatin.
>You all be the judge.
>
>I had to redo the curve several times to adjust for increased pigment load
>and the fact that with increased pigment load I had to expose longer--I
>ended up with a 9 minute UVBL exposure for a one coat carbon.
>
>What I proved to myself is that one can certainly get a fully tonal gum
>print with dmax in one coat. Will it rival a platinum or carbon (if I could
>actually SEE a carbon)? Probably not. Is it better to do a fully tonal
>print in more than one coat? Probably easier. Do you need to expose from
>the back to keep the layer adhered to the paper and fully tonal? Why? If
>you expose long enough to harden the layer to the paper base and curve
>properly so at that time you still have highlights, it should be fine. The
>need for a curve and a perfectly sized and hardened paper goes without
>saying and should be apparent in the comparison.
>
>Open the floodgates...
>Chris
>
>----- Original Message ----- From: "Yves Gauvreau"
><gauvreau-yves@sympatico.ca>
>To: <alt-photo-process-l@usask.ca>
>Sent: Saturday, April 29, 2006 6:32 AM
>Subject: Re: Back-exposing on plastic (was: Re: Gum transfer
>
>
>Mark,
>
>thanks you very much, you have summurised what I have been saying all along
>from my first message here on this list about gum. Gum is just another
>photographic process, nothing esoteric about it and just like another
>process, gum as its features and true these makes gum a distinctive process
>but still a photographic process.
>
>Regards
>Yves
>
>
> ----- Original Message ----- From: Ender100@aol.com
> To: alt-photo-process-l@usask.ca
> Sent: Friday, April 28, 2006 1:48 PM
> Subject: Re: Back-exposing on plastic (was: Re: Gum transfer
>
>
> Yves,
>
> The gum variables can be modified to change the Exposure Scale of the
>printing. If you first adjust the density range of the negative prior to
>applying a curve, then you will get the maximum from the gum print-then the
>curve is only used to adjust the relative tonalities between DMax and Paper
>White. The adjustment of the density range of the negative is pretty
>important for gum, since it has a shorter exposure scale than many other
>processes and requires a lower density range negative. Doing this is one
>(just one) reason why Chris Anderson is having so much success with her tri
>color gum thingies.
>
> An example might be making a negative with an Epson 2200 where the UV
>transmission density of a negative using all inks can be over log 4.0-so if
>you need a negative to match an exposure scale of gum at let's say log 1.2,
>then you have a mismatch of 4.0 - 1.2 or log 2.8 TOO much density in the
>negative that the curve has to adjust for-that is over 7 stops! This is why
>you often see people using curves where the endpoint has been moved to
>reduce the density so the highlights won't blow out... unfotrunately for
>every point that you move that endpoint, you lose that many tones in the
>negative. You can actually use this to calculate exactly how many tones
>will be lost.
>
> Best Wishes,
> Mark Nelson
> Precision Digital Negatives--The Book
> PDNPrint Forum at Yahoo Groups
> www.MarkINelsonPhoto.com
>
> In a message dated 4/28/06 10:43:12 AM, gauvreau-yves@sympatico.ca writes:
>
>
>
> Katharine,
>
> my first reply on this topic was probably the cause of the
>misunderstanding,
> when I read it back now I see what you mean. With the last one I thought
>I
> made all this as clear as I can but I'll try again. If whatever you do
>back
> exposing your print fails to give you a satisfying tonal "delicacy" as
>you
> put it, may be applying a different curve would help.
>
> If I understand normaly exposed gum printing (front exposed) you can
>control
> the distribution of pigment (tonal "delicacy") by the various usual
>means
> including % gum, % pigment, % dichromate, thickness of emultion,
> exposure(s), development and physical manipulations, etc. With back
> exposure, it seems only one exposure can be done and all I'm saying is
>that
> beside all the usual controls you have the possibility to change the
> negative density (distribution) by applying some curve. Can you control
> every thing with some curve, the answer is simple no. The reason for
>this is
> that a couple variables of the gum process are totally independent of
> exposure (negative densities), the pigment load, as you call it, is one
>of
> these, development and physical manipulations are other mean by which
>you
> can alter the tonal distribution, in the limit you can scrape it all off
> (the emultion).
>
>
> I would certainly claim that if you maintain every variables fix ie. you
> don't change anything from print to print except the curve applied to
>the
> negative, you can basically obtain any tone you want between the Dmax
>and
> the Dmin of the print. Obviously, this fix variable gum print must show
> something usable to begin with.
>
> Regards
> Yves
Received on Mon May 1 00:13:42 2006