Re: Back-exposing on plastic (was: Re: Gum transfer

Terry,

yes, I recall you said a negative density of around 0.7 should work fine for gum but that doesn't say how much the Dmax of the print will be and if I understand correctly Sandy's 1.2 figure is about exactly that, the Dmax of the print not the negative.

We may be arguing for nothing here, hopefully I will be able to keep up with this statement but I would "never" claim you can't make a gum print without using a curve or a digi-neg for that matter, that would be stupid on my part after all gum as been around well before computers.

All this I wrote below is basically about how to make a negative by which ever mean you like that will expose the gum emultion in such a way as to provide some apparently continuous tones from a minimum to a maximum value. The specific values are irrelevent, if light could be held in very small bucket I would say you want this tone then use this many buckets and you got it, you want that tone then use that many buckets. For me, controling the densities of a negative is just like saying how many buckets of light you need and where you want it, if you view the density of a negative not as an obstacle to light but as a passage of light then the analogy with buckets makes more sense. I would just add I'd rather push a few keystrokes then have to carry buckets around however small they may be.

I'm convinced what we say is not incompatible, I don't know, maybe someday humans won't need words to communicate and this may solve many things.

Regards
Yves

  ----- Original Message -----
  From: TERRYAKING@aol.com
  To: alt-photo-process-l@usask.ca
  Sent: Wednesday, May 03, 2006 5:32 AM
  Subject: Re: Back-exposing on plastic (was: Re: Gum transfer

  In a message dated 3/5/06 8:29:50 am, gauvreau-yves@sympatico.ca writes:

    But if I was satisfied with a relatively low Dmax, say the 1.2 as Sandy said earlier and the relatively flat response obtainable from a single coat gum print. I would approach the problem this way, first I would make enough gum emultion such that can make quite a few test and prints without changing anything to my recipe. One of my first test would be to find how much exposure I need to secure the target Dmax. The next test would be to print a standard step tablet to learn the response of this particular emultion/paper combo if not already done simultaniously in the exposure test. Now I don't presuppose a linear response would suit the image just like that and I would use a negative feedback approach to find what kind of curve I will use for this image on this particular emultion. The way this would be done is say I print a negative where the densities progress in a strait line from min to max and to compare it with a different version, I could begin by increasing the contrast in the highlights, if I don't like that I could try the same with the shadow and so on until I'm satisfied I've made the finest print I could.

  Yves

  That is not how gum works.

  Gum has a limited density rande. The maximum for ideal gradation is probably about half of what Sandy suggests. One overcomes this by overlapping multiple exposures. I do so as I control the colour this way. An alternative for monochrome printing could be to use a very fine grain pigment which may result in an appearance of good gradation and range. That is what I am about to check in the articles in La Revue de Photographie. Another good source would be Photograms of the Year.Both have articles by the likes of Steichen, Puyo and Demarchy.

  I remain unconvinced that the use of digital negatives has anything to do with it. After all, Puyo was making these monochrome single exposure prints in 1900 !

  Terry
Received on 05/03/06-09:37:37 AM Z